Co-reporter:
Macromolecular Chemistry and Physics 2017 Volume 218(Issue 4) pp:
Publication Date(Web):2017/02/01
DOI:10.1002/macp.201600451
Hybrid composites with highly ordered structures show promise for applications in various fields and thus there is great interest in their fabrication. In this context, Janus nanoparticles (JNPs) are synthesized with the aim of further incorporating them into polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) block copolymers to fabricate hybrid composites. It is observed that the dispersed JNPs are located at the boundary of the two morphological phases in PS-b-P2VP. The orientation of the lamellar structure in the bottom and free surface region of the block copolymer (BCP) composites shows a distinct difference as the composition of the JNPs is adjusted. The processing conditions of the nanoparticle/BCP composites are found to play an important role in achieving the desired structures.
Co-reporter:Qiuyan Yang
Polymer Chemistry (2010-Present) 2017 vol. 8(Issue 4) pp:641-654
Publication Date(Web):2017/01/24
DOI:10.1039/C6PY01795A
Control of the location and spatial organization of nanoparticles (NPs) inside polymers is essential to generate highly ordered NP-based functional devices including plasmonic waveguides, photonic crystals, optical lenses, memory storage devices, nanoelectronic circuits, photovoltaics, and batteries. Due to the unique combination of amphiphilicity and the particle character, Janus nanoparticles (JNPs) show high interfacial activity at fluid–fluid interfaces and in the bulk (for example, polymer blends and block copolymers (BCPs)). Interfacial incorporation of Janus NPs inside a polymeric matrix can endow polymeric materials with improved mechanical and additional properties from ordinary NPs. Here, different from other reports providing general overviews on the synthesis and applications of JNPs, this review specifically highlights recent advances and success in interfacial behavior of Janus NPs at polymer interfaces. We hope that these accomplishments will motivate additional efforts in large-scale synthesis and interfacial behavior studies of Janus NPs in polymer matrices allowing the design of functional hybrid nanostructures and devices with engineered, desired and tailored properties for real-life applications.
Co-reporter:Csaba Fodor;Milad Golkaram;Albert J. J. Woortman;Jur van Dijken
Polymer Chemistry (2010-Present) 2017 vol. 8(Issue 44) pp:6795-6805
Publication Date(Web):2017/11/14
DOI:10.1039/C7PY01559C
Aromatic moieties containing oligoesters have been synthesized by enzymatic polymerization of AB-type alkylenehydroxybenzoates via different polymerization methods. Oligo(2-hydroxyethoxy benzoate) (OHEBA) was obtained with number average molecular weights (Mn) around 2000 g mol−1. A low degree of polymerization was achieved or no oligomer formation was observed from the enzymatic reaction of compounds modified by one or more methoxy groups. MALDI-TOF MS analysis suggests that the most dominant species in the resulting HEBA oligomer samples are ester/–OH end groups. The thermal properties of the enzymatically produced oligoesters were fully characterized using DSC, TGA and WAXD as well as rheology studies and have been compared with higher molecular weight polymers prepared by conventional polycondensation reactions from the same p-hydroxy benzoic acid derivative. These semi-crystalline oligomers and polymers were found to be mimicking the thermoplastic aromatic/aliphatic polyester regarding their macromolecular structure and thermal behavior. The molecular weight of the obtained AB-type OHEBA was successfully increased to 13 050 g mol−1 by using it as a macromolecular monomer in sequential polymerization.
Co-reporter:Anton H. Hofman, Gerrit ten Brinke, Katja Loos
Polymer 2017 Volume 121(Volume 121) pp:
Publication Date(Web):14 July 2017
DOI:10.1016/j.polymer.2017.05.057
•Self-assembly of asymmetric supramolecular double-comb diblock copolymers was studied by SAXS, TEM and DSC.•Analogue to conventional covalent bottlebrush block copolymers, formation of a curved interface was often avoided.•The ability of the side chains to crystallize was, however, found to dominate microphase separation.•Therefore, their phase behavior closely resembles that of semicrystalline block copolymers.•Depending on the grafting density, breakout crystallization, confined crystallization or plasticization was observed.The combination of asymmetric P4VP-b-PAPI diblock copolymers (i.e. fP4VP≠fPAPI) and 3-NDP surfactants in hydrogen-bonded [poly(4-vinylpyridine)-block-poly(N-acryloylpiperidine)](3-nonadecylphenol)x (P4PA(3-NDP)x) supramolecular double-comb diblock copolymers could potentially result in rather interesting morphologies. However, plasticization of the copolymer and the ability of 3-NDP to crystallize were found to affect their self-assembly significantly. In general, for high comb densities x, the complex's tendency to crystallize and its preference to form a flat interface dominated microphase separation. Lower values of x on the other hand gave uneven distribution of 3-NDP, resulting in a higher glass transition temperature of the P4VP block. Crystallization of 3-NDP's aliphatic tails was therefore in most cases restricted to the preferential PAPI microdomains, thereby maintaining the large length scale block copolymer morphology that was already present in the melt. Such behavior is identical to self-assembly of linear semicrystalline diblock copolymers, as in these type of systems structure formation depends on the segregation strength and relative magnitude of the order-disorder transition (TODT), Tg and Tc, leading to mechanisms like confined crystallization or breakout.Download high-res image (336KB)Download full-size image
Co-reporter:Anna Casadellà;Olivier Schaetzle
Macromolecular Rapid Communications 2016 Volume 37( Issue 10) pp:858-864
Publication Date(Web):
DOI:10.1002/marc.201600032
Co-reporter:Martin Faber;Anton H. Hofman;Gerrit ten Brinke
Macromolecular Rapid Communications 2016 Volume 37( Issue 11) pp:911-919
Publication Date(Web):
DOI:10.1002/marc.201600052
Co-reporter:Yi Jiang, Dina Maniar, Albert J. J. Woortman and Katja Loos
RSC Advances 2016 vol. 6(Issue 72) pp:67941-67953
Publication Date(Web):11 Jul 2016
DOI:10.1039/C6RA14585J
2,5-Furandicarboxylic acid (FDCA)-based semi-aromatic polyamides are novel biobased alternatives to petrol-based semi-aromatic polyamides (polyphthalamides), that have a broad commercial interest as engineering thermoplastics and high performance materials. In this study, a series of FDCA-based semi-aromatic polyamides is successfully produced via Novozym®435 (N435, an immobilized form of Candida antarctica lipase b (CALB))-catalyzed polycondensation of (potentially) biobased dimethyl 2,5-furandicarboxylate and aliphatic diamines differing in chain length (C4–C12), using a one-stage method at 90 °C in toluene. The obtained polyamides reach high weight-average molecular weights ranging from 15800 to 48300 g mol−1; and N435 shows the highest selectivity towards 1,8-octanediame (C8). MALDI-ToF MS analysis indicates that no byproducts are formed during the enzymatic polymerization. Study of the kinetics of the enzymatic polymerization suggests that phase separation of FDCA-based oligoamides/polyamides takes place in the early stage of polymerization, and the isolated products undergo an enzyme-catalyzed solid-state polymerization. However, the isolation yields of the purified products from the enzymatic polymerizations are less than ∼50% due to the production of a large amount of low molecular weight products that are washed away during the purification steps. Furthermore, the thermal properties of the enzymatic FDCA-based semi-aromatic polyamides are carefully investigated, and compared to those of the FDCA-based and petrol-based counterparts produced via conventional synthesis techniques as reported in literature.
Co-reporter:Anna Casadellà;Anne Haye Galama;Olivier Schaetzle
Macromolecular Chemistry and Physics 2016 Volume 217( Issue 14) pp:1600-1606
Publication Date(Web):
DOI:10.1002/macp.201600037
Co-reporter:Martin Faber, Anton H. Hofman, Nanda Harinck, Mark ten Cate, Katja Loos, Gerrit ten Brinke
Polymer 2016 Volume 92() pp:273-282
Publication Date(Web):1 June 2016
DOI:10.1016/j.polymer.2016.03.090
•Poly(p-hydroxystyrene) was synthesized via anionic polymerization.•Self-assembly of hydrogen-bonded comb copolymer complexes poly(p-hydroxystyrene) with various 4-alkylpyridines was studied.•Ordered structures are observed in which the disorder-order transition and crystallization occur quasi simultaneously.•No liquid crystalline ordering can be observed.The self-assembly of the hydrogen-bonded complexes between poly(p-hydroxystyrene) (PpHS) and 4-alkylpyridine amphiphiles is studied using infrared spectroscopy, differential scanning calorimetry, polarized optical microscopy, transmission electron microscopy and small- and wide-angle X-ray scattering. Interesting differences are observed with the well-studied inverted system of poly(4-vinylpyridine) and alkylphenol amphiphiles. When the alkyl tails of the 4-alkylpyridine amphiphiles are long enough, 19 and 21 respectively, an ordered lamellar structure is formed on cooling where the ordering and crystallization of the alkyl tails occur quasi simultaneously. For a shorter alkyl tail of length 17 no ordered structure is formed. This is quite different from the inverted P4VP/alkylphenol systems, where already for an alkyl tail of length 15, i.e., pentadecylphenol, an ordered structure is formed below ca. 55 °C, followed by crystallization of the alkyl tails at ca. 20 °C. This can be attributed to the possibility of (intramolecular) hydrogen bond formation of PpHS.
Co-reporter:Anton H. Hofman, Gerrit ten Brinke, Katja Loos
Polymer 2016 Volume 107() pp:343-356
Publication Date(Web):19 December 2016
DOI:10.1016/j.polymer.2016.08.021
•Supramolecular chemistry enables facile design of complex macromolecular architectures.•The combination of conventional linear block copolymers and surface active molecules results in comb-shaped copolymers.•Sufficiently strong segregation often leads to spontaneous hierarchical structure formation.•Materials for optics and electronics can be prepared by incorporation of functionality in the polymer or surfactant.•This feature article provides a selection of the most recent work performed in the field.Block copolymers are known to spontaneously form ordered structures at the nano-to mesoscale. Although the number of different morphologies is rather limited in diblock copolymer systems, their phase behavior becomes increasingly more complex with each additional building block. Synthesis of such all-covalent materials is, however, a very challenging task. By moving to supramolecular chemistry these preparation methods can be avoided while maintaining the same kind of macromolecular complexity. After a brief introduction, this feature article will provide a selection of the most recent work performed in the field of self-assembling supramolecular block copolymer-containing materials. By careful choice of both the copolymer and, in many cases, the small organic surface active compound, fascinating morphologies can appear in supramolecular comb-shaped block copolymers. Several examples will be discussed, while a number of functional materials (e.g. thermal, optical, electronic) originating from these type of complexes will be addressed as well.
Co-reporter:Katja Loos
Polymer 2016 Volume 107() pp:341-342
Publication Date(Web):19 December 2016
DOI:10.1016/j.polymer.2016.09.090
Co-reporter:Dejan M. Petrović, Inge Kok, Albert J. J. Woortman, Jelena Ćirić, and Katja Loos
Analytical Chemistry 2015 Volume 87(Issue 19) pp:9639
Publication Date(Web):August 20, 2015
DOI:10.1021/acs.analchem.5b01098
Much progress was made in the straightforward and eco-friendly enzymatic synthesis of shorter cellulose chains (oligocellulose). Here, we report the determination of a molar mass distribution of the oligocellulose synthesized from cellobiose (CB) and α-glucose 1-phosphate by reverse phosphorolysis, using enzymes cellodextrin phosphorylase from Clostridium stercorarium or Clostridium thermocellum as catalyst. The oligocellulose molar mass distribution was analyzed using three different methods: 1H NMR spectroscopy, matrix assisted laser desorption/ionization–time-of-flight mass spectrometry (MALDI-ToF MS) and size exclusion chromatography (SEC). The molar mass distribution of the synthesized oligocellulose was only dependent on the concentration of cellobiose used in the reaction. Data obtained from MALDI-ToF MS and SEC were almost identical and showed that oligocellulose synthesized using 10 mM CB has an average degree of polymerization (DPn) of ∼7, while a DPn of ∼14 was achieved when 0.2 mM CB was used in the reaction. Because of solvent limitation in SEC analysis, MALDI-ToF MS was shown to be the technique of choice for accurate, easy and fast oligocellulose molar mass distribution determination.
Co-reporter:Anton H. Hofman, Gert O. R. Alberda van Ekenstein, Albert J. J. Woortman, Gerrit ten Brinke and Katja Loos
Polymer Chemistry 2015 vol. 6(Issue 39) pp:7015-7026
Publication Date(Web):13 Aug 2015
DOI:10.1039/C5PY00952A
Controlled radical polymerization of 4-vinylpyridine (4VP) and N-acryloylpiperidine (API) by the RAFT process allowed preparation of well-defined double hydrogen bond accepting P4VP-b-PAPI diblock copolymers. The miscibility of this new monomer pair was studied via a random copolymer blend approach and resulted in a Flory–Huggins interaction parameter χ4VP,API ≈ 0.03, which is higher than the commonly used styrene/MMA couple, but lower compared to styrene/isoprene. This value was found to support the bulk phase behavior of a series of diblock copolymers as evidenced by SAXS and TEM. Highly ordered structures, including cylinders, lamellae and spheres, were identified in these materials, even in diblocks of higher molecular weight and broader distribution, while a disordered morphology was indeed observed in a symmetric, low molecular weight analogue.
Co-reporter:Yi Jiang, Albert J. J. Woortman, Gert O. R. Alberda van Ekenstein and Katja Loos
Polymer Chemistry 2015 vol. 6(Issue 30) pp:5451-5463
Publication Date(Web):17 Jun 2015
DOI:10.1039/C5PY00660K
Aliphatic polyesters are of great interest due to their broad potential applications and sustainability. Itaconate-based aliphatic polyesters are even more appealing in biomedical and pharmaceutical fields, as they are renewable functional polymers that can be biodegradable, biocompatible, and photo-curable, and might be bioresorbable. Herein, various biobased saturated aliphatic polyesters and itaconate-based unsaturated aliphatic polyesters are successfully produced via Candida antarctica Lipase B (CALB)-catalyzed polycondensation of (potentially) biobased dimethyl itaconate, 1,4-butanediol and various diacid ethyl esters, using a two-stage method in diphenyl ether. The synthetic aliphatic polyesters reach high (weight average molecular weight) values up to 94 kg mol−1. Studies on the effect of diacid ethyl esters on the enzymatic polymerization reveal that CALB prefers diacid ethyl esters having a chain length of more than 2 (n > 2, n is the number of methylene groups between the two carbonyl groups); and CALB shows the highest specificity for diethyl adipate among the tested diacid ethyl esters (n = 2–10). Moreover, the structure–property relationships are discussed by investigating the chemical structures, crystalline properties and thermal properties of the obtained aliphatic polyesters, as well as, the thermal transitions and mechanical properties of the UV cross-linked unsaturated polyesters.
Co-reporter:Yi Jiang, Albert J. J. Woortman, Gert O. R. Alberda van Ekenstein and Katja Loos
Polymer Chemistry 2015 vol. 6(Issue 29) pp:5198-5211
Publication Date(Web):20 May 2015
DOI:10.1039/C5PY00629E
An eco-friendly approach towards furanic–aliphatic polyesters as sustainable alternatives to aromatic–aliphatic polyesters is presented. In this approach, biobased dimethyl 2,5-furandicarboxylate (DMFDCA) is polymerized with various (potentially) renewable aliphatic diols via Candida antarctica Lipase B (CALB)-catalyzed polymerization using a two-stage method in diphenyl ether. A series of furanic–aliphatic polyesters and oligoesters is successfully produced via enzymatic polymerization. Some products reach very high (weight average molecular weight) values of around 100000 g mol−1. Studies on the effect of the diol structure on the enzymatic polymerization indicate that CALB prefers long-chain alkane-α,ω-aliphatic linear diols containing more than 3 carbons. We also found that the molecular weights of the obtained furanic–aliphatic polyesters increase steadily with the increase of reaction temperature from 80 to 140 °C. MALDI-ToF MS analysis reveals that five polyester species may be present in the final products. They were terminated with the ester/–OH, ester/ester, –OH/–OH, no end groups (cyclic), and ester/aldehyde groups, respectively. Furthermore, the structure–property relationships were studied by comparing the crystalline/thermal properties of a series of relevant furanic–aliphatic polyesters.
Co-reporter:Vincent S. D. Voet;Kamlesh Kumar;Gerrit ten Brinke
Macromolecular Rapid Communications 2015 Volume 36( Issue 19) pp:1756-1760
Publication Date(Web):
DOI:10.1002/marc.201500301
Co-reporter:Kamlesh Kumar;Albert J. J. Woortman
Macromolecular Rapid Communications 2015 Volume 36( Issue 23) pp:2097-2101
Publication Date(Web):
DOI:10.1002/marc.201500343
Co-reporter:Zheng Cao;Albert J. J. Woortman;Petra Rudolf
Macromolecular Bioscience 2015 Volume 15( Issue 5) pp:691-697
Publication Date(Web):
DOI:10.1002/mabi.201400464
Amylose-fatty acid inclusion complexes can be easily prepared by simple mixing in hot aqueous solutions. Above a critical chain length (C6) of the fatty acid insoluble complexes between amylose and each fatty acid (C8, C10, C12, C14, C16) were precipitated from the solution, and characterized by FT-IR, XRD, DSC, and SEC. The presence of the characteristic (CO) FT-IR absorption peak at 1 710 cm−1 confirmed the inclusion of the fatty acids inside the amylose helix. XRD showed the same characteristic features of the V amylose single helical structure. Both SEC and DSC revealed that longer fatty acids can form inclusion complexes with amylose fractions having higher degree of polymerization, leading to greater yields, and higher thermal stability (higher melting temperature and enthalpy) of the amylose-complexes.
Co-reporter:Rachmawati Rachmawati;Albert J. J. Woortman;Kamlesh Kumar
Macromolecular Bioscience 2015 Volume 15( Issue 6) pp:812-828
Publication Date(Web):
DOI:10.1002/mabi.201400515
Amylose inclusion complexes are prepared by complexation of synthetic amylose having a covalently attached PTHF block (PTHF-b-amylose) with guest polytetrahydrofuran of molecular weights of 650 and 1000 g · mol−1 (PTHF650 and PTHF1000). Differential Scanning Calorimetry (DSC) analysis of the products shows a characteristic melting peak of the complexes at 140 °C. Compared to PTHF650, the PTHF1000 displays lower complexing ability with PTHF-b-amylose which is indicated by visible amylose retrogradation. The possible structures of the resulting products are estimated from Thermo Gravimetric Analysis (TGA) which reveals differences between PTHF-b-amylose and the corresponding complexes. In addition, X-Ray Diffraction (XRD) analysis demonstrates that the resulting structures of the complexes consist of 6-fold V-amylose helices. The results are confirmed further with Small Angle X-Ray Scattering (SAXS) diffractions which show that formation of inclusion complexes increases the crystalline size and regularity of the complex. There is a strong indication that the covalently attached PTHF block also induces the formation of V-amylose by residing in between the amylose blocks. In this case, the resulting structure of the complex is likely affected by both the complexation between amylose block and the added PTHF and by the in situ self-assembly of the block copolymers.
Co-reporter:S. Ahmadi-Abhari, A.J.J. Woortman, R.J. Hamer, K. Loos
Carbohydrate Polymers 2015 Volume 122() pp:197-201
Publication Date(Web):20 May 2015
DOI:10.1016/j.carbpol.2014.12.063
•Amylose–LPC complexation was induced at different starch gelation phases.•Starch shows different viscosity behaviors due to LPC addition at each gelation phase.•Adding LPC after an initial gelation, results in a sharp viscosity peak during cooling.•Lower G′ and G″ prove the formation of particle gel, resulting in less retrogradation.Amylose is able to form helical inclusion complexes with lysophosphatidylcholine (LPC). This complexation influences the functional and rheological properties of wheat starch; however it is well known that the formation of these complexes lead the starchy systems to a slower enzymatic hydrolysis. Based on this, to benefit from both the structuring properties of starch and also lower digestibility of the inclusion complexes, the objective of this study is the formation of amylose–LPC inclusion complexes while developing a firm network providing the desired functional properties in a starchy system. To investigate the influence of amylose–LPC complex formation at different stages of starch gelation on the viscosity behavior of wheat starch, 3% (w/w) LPC was added at three different points of the viscosity profile, obtained by rapid visco analyzer (RVA). LPC addition at all points affected the gelation behavior of wheat starch as compared with the reference. LPC addition at half-peak and peak of the viscosity profile resulted in a viscosity increase during cooling. Measuring the dynamic rheological properties of the freshly prepared gelatinized samples showed a decrease of storage modulus (G′) and loss modulus (G″) in the presence of LPC. During storage, in the presence of LPC, a lower elasticity was observed which indicates a lower rate of amylose retrogradation due to complexation with LPC.
Co-reporter:Kamlesh Kumar, Marjon Boonstra and Katja Loos
RSC Advances 2015 vol. 5(Issue 42) pp:33294-33298
Publication Date(Web):30 Mar 2015
DOI:10.1039/C5RA04185F
Carbon microrings were produced using a template based on phase separation of amylose/pentadecyl phenol (PDP)/dimethyl sulfoxide (DMSO) mixtures. The two-step phase separation of the mixture showed a micron-sized porous structure in which the rim of the pores was enclosed by rings of PDP. PDP was converted into a carbon precursor resin via reaction with formaldehyde vapor followed by pyrolysis under nitrogen atmosphere, leading to a carbon microstructure with ring morphology. The products before and after pyrolysis were characterized by Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDX). AFM and SEM confirmed the ring morphology of the samples obtained after pyrolysis. The presence and phase of carbon were confirmed by EDX and XRD, respectively. This study demonstrates a straightforward novel route to prepare carbon microrings from a phenolic precursor using amylose as a matrix material.
Co-reporter:Jing Li, Shijun Zheng, Xiaobo Wang, Hongxia Yang, Katja Loos, Qun Xu
Materials Letters 2015 Volume 158() pp:147-150
Publication Date(Web):1 November 2015
DOI:10.1016/j.matlet.2015.05.043
•The PFFB/GO nanohybrids were obtained with the assistance of SC CO2.•SC CO2 played a key role in enhancing the PL intensity of the nanohybrids.•SC CO2 can help PFFB transfer from one morphology to another.Fluorinated polyylidenefluorenes derivative, poly [(9-ylidene-{2-tetradecyloxy-5-tetrafluorophthalimide-phenyl}fluorenyl-2,7-diyl)-alt-(1,4-phenyl)] (PFFB)/graphene oxide (GO) nanohybrids (SC-PFFB/GO) were successfully fabricated via a facile method with the assistance of supercritical CO2 (SC CO2). It was fascinating to observe that the photoluminescence (PL) intensity at 410 nm of SC-PFFB/GO was 6 times that of PFFB/GO. The experimental results of TEM characterization indicated that PFFB preferred to crystallize rather than form amorphous aggregates on GO nanosheets with the assistance of SC CO2. So our experimental results are a proof of concept that SC CO2 is an efficient method to help PFFB transfer from one morphology to another and the fluorescent behavior of the obtained nanohybrids can be improved greatly due to the effect of SC CO2.
Co-reporter:Rachmawati Rachmawati;Hilde D. de Gier;Albert J. J. Woortman
Macromolecular Chemistry and Physics 2015 Volume 216( Issue 10) pp:1091-1102
Publication Date(Web):
DOI:10.1002/macp.201500018
Co-reporter:Yi Jiang, Dina Maniar, Albert J. J. Woortman, Gert O. R. Alberda van Ekenstein, and Katja Loos
Biomacromolecules 2015 Volume 16(Issue 11) pp:
Publication Date(Web):September 29, 2015
DOI:10.1021/acs.biomac.5b01172
Furan-2,5-dicarboxylic acid (FDCA)-based furanic-aliphatic polyamides can be used as promising sustainable alternatives to polyphthalamides (semiaromatic polyamides) and be applied as high performance materials with great commercial interest. In this study, poly(octamethylene furanamide) (PA8F), an analog to poly(octamethylene terephthalamide) (PA8T), is successfully produced via Novozym 435 (N435)-catalyzed polymerization, using a one-stage method in toluene and a temperature-varied two-stage method in diphenyl ether, respectively. The enzymatic polymerization results in PA8F with high weight-average molecular weight () up to 54000 g/mol. Studies on the one-stage enzymatic polymerization in toluene indicate that the molecular weights of PA8F increase significantly with the concentration of N435; with an optimal reaction temperature of 90 °C. The temperature-varied, two-stage enzymatic polymerization in diphenyl ether yields PA8F with higher molecular weights, as compared to the one-stage procedure, at higher reaction temperatures. MALDI-ToF MS analysis suggests that eight end groups are present in the obtained PA8F: ester/amine, ester/ester, amine/amine, acid/amine, ester/acid, acid/acid, ester/amide, and no end groups (cyclic). Compared to PA8T, the obtained PA8F possesses a similar Tg and similar crystal structures, a comparable Td, but a lower Tm.
Co-reporter:Anton H. Hofman, Yexing Chen, Gerrit ten Brinke, and Katja Loos
Macromolecules 2015 Volume 48(Issue 5) pp:1554-1562
Publication Date(Web):February 27, 2015
DOI:10.1021/acs.macromol.5b00141
The self-assembly of P4VP(3-PDP)1.0 and P4VP(4-NDP)1.0 supramolecular comb-shaped copolymers has previously been shown to have very interesting thermal properties, since besides crystallization of 3-PDP/4-NDP’s alkyl tails, an additional order–disorder transition (ODT) was observed as well. In order to get a better insight into the processes involved and the parameters that determine this behavior, a library consisting of differently substituted n-alkylphenol surfactant molecules was synthesized. A general trend was found in the stoichiometric P4VP-based complexes. As expected, both the melting point and long period of the lamellar structure increased with a longer tail length, while surprisingly TODT only depended on the position of the hydroxyl group. Its magnitude is assumed to be directly related to the strength of hydrogen bonding, which is highest for the sterically least hindered surfactants (para). Additionally, critical behavior was discovered in meta-substituted complexes: a large reduction in both Tm and TODT was observed for a 13 methylene unit long amphiphile, while crystallization of the alkyl tails determined the self-assembly in P4VP(3-henicosylphenol)1.0.
Co-reporter:Qiuyan Yang, Qun Xu, and Katja Loos
Macromolecules 2015 Volume 48(Issue 6) pp:1786-1794
Publication Date(Web):March 9, 2015
DOI:10.1021/ma5025686
The surface properties of polystyrene (PS) films under carbon dioxide (CO2) were studied via a particle embedding technique at quite a low temperature range (308–323 K) in which polystyrene is typically considered to be in a glassy state without CO2. The atomic force microscope (AFM) technique with a tapping mode was used to get the height profiles of gold nanoparticles on the PS film surfaces and PS colloidal crystals for statistical analysis. The embedding of gold nanoparticles demonstrates that the surface mobility of polystyrene was greatly enhanced by exposing it to CO2, with further experimental confirmation by the study of welding polystyrene colloidal crystals under CO2 conditions. Surface mobility as well as embedding depths (from 2 to 17 nm) of nanoparticles is adjustable depending on the CO2 condition applied.
Co-reporter:Wouter M. J. Kloosterman, Danijela Jovanovic, Sander G. M. Brouwer and Katja Loos
Green Chemistry 2014 vol. 16(Issue 1) pp:203-210
Publication Date(Web):26 Sep 2013
DOI:10.1039/C3GC41471J
The enzymatic synthesis of novel (di)saccharide acrylates from starch and 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate and 4-hydroxybutyl acrylate (2-HEA, 2-HEMA and 4-HBA) catalyzed by various commercially available amylase preparations is demonstrated. Both liquefaction and saccharification amylases were tested as biocatalysts. Transglycosidation products were only detected in reaction mixtures containing saccharification amylases. The glycoamylase from Aspergillus niger was found to catalyze the synthesis of 2-(α-glucosyloxy)-ethyl acrylate (Glc-α-EA) from starch. The maltogenic amylase from B. stearothermophilus was found to catalyze the synthesis of 2-(α-maltosyloxy)-ethyl acrylate (Glc-Glc-EA). The transglycosidation product was isolated and purified and its structure was confirmed by 1H-NMR, 13C-NMR and ESI mass spectrometry. The selectivity of the enzyme towards the glycosidation position appeared to be extremely high. Only the anomeric hydroxyl group (C1–OH) of the disaccharide appeared to be glycosidated and the glycosidation products were anomerically pure. Subsequently, the enzymatically synthesized maltosyl acrylate was successfully polymerized by aqueous free radical polymerization to yield a novel acrylic polymer with pendant maltosyl units.
Co-reporter:Wouter M. J. Kloosterman, Steven Roest, Siti R. Priatna, Erythrina Stavila and Katja Loos
Green Chemistry 2014 vol. 16(Issue 4) pp:1837-1846
Publication Date(Web):23 Jul 2013
DOI:10.1039/C3GC41115J
Novel types of glucosyl-acrylate monomers are obtained by β-glucosidase from almond catalyzed glycosidation reaction. The saccharide-acrylate monomers were synthesized by reaction of D-glucose with hydroxyl functional acrylates: 2-hydroxyethyl acrylate (2-HEA), 2-hydroxyethyl methacrylate (2-HEMA) and 4-hydroxybutyl acrylate (4-HBA). The reaction products could be identified as 2-(β-glucosyloxy)-ethyl acrylate, 2-(β-glucosyloxy)-ethyl methacrylate and 4-(β-glucosyloxy)-ethyl acrylate respectively. The synthesis yield was optimized by variation of the 2-HEA–water ratio, the presence of water-miscible co-solvents and the reaction time. The optimal reaction mixture was found to contain 13 vol% water, 80 vol% 2-HEA and 7 vol%; 1.4-dioxane. The maximal yield under these conditions was 50 wt% based on D-glucose after 24 hours of reaction. The enzymatically synthesized glucosyl-acrylates were successfully polymerized by free radical polymerization in DMF and water. The glycosidic linkage of the glycosyl-acrylate monomers was retained during the polymerization process. The enzymatically synthesized glucosyl-acrylates could be successfully copolymerized with vinyl monomers 2-HEA, 2-HEMA, methacryl amide and N-vinyl imidazole.
Co-reporter:Vincent S. D. Voet, Gert O. R. Alberda van Ekenstein, Niels. L. Meereboer, Anton H. Hofman, Gerrit ten Brinke and Katja Loos
Polymer Chemistry 2014 vol. 5(Issue 7) pp:2219-2230
Publication Date(Web):18 Dec 2013
DOI:10.1039/C3PY01560B
Double-crystalline poly(L-lactide)-block-poly(vinylidene fluoride)-block-poly(L-lactide) (PLLA-b-PVDF-b-PLLA) triblock copolymers were successfully synthesized through ring opening polymerization of L-lactide and benzoyl peroxide initiated polymerization of vinylidene fluoride, followed by copper(I)-catalyzed azide–alkyne coupling of the functionalized PLLA and PVDF. Three triblock copolymers with different block ratios were prepared via this synthetic approach. The block copolymers were miscible in the melt, and an alternating crystalline lamellar nanostructure was formed upon crystallization from the homogeneous melt. Crystallization behavior of the PLLA component depends strongly on the block composition. The crystallization temperature of the lower temperature crystallizing PLLA block increased considerably with respect to its parent homopolymer for rather symmetric block copolymers, indicating a strong nucleation effect, while on the other hand asymmetric block copolymers with low PLLA content demonstrated a large decrease of crystallization temperature, due to a fractionated crystallization process. A confined crystallization mechanism for the PLLA blocks was suggested, indicated by the low degree of crystallization compared to the respective homopolymers, and confirmed by microstructure analysis performed during isothermal crystallization. Contrary to PLLA, crystallization of the higher temperature crystallizing PVDF component within the block copolymer was not influenced by the block composition and similar crystallization behavior was observed with respect to PVDF homopolymers.
Co-reporter:Jelena Ciric, Albert J.J. Woortman, Katja Loos
Carbohydrate Polymers 2014 Volume 112() pp:458-461
Publication Date(Web):4 November 2014
DOI:10.1016/j.carbpol.2014.05.093
•PFG columns can be used for starch analysis.•Good amylose and debranched amylopectin separation.•Amylose content can be determined.Debranched starches were tested with a previously developed method for size exclusion chromatography (SEC) with multi detection utilizing different columns than usually used for the separation of starch in DMSO. A number of debranched starches were analyzed. This system allows good separation of amylose and amylopectin after debranching of starch, and provides quantitative information on the amylose content. Additionally molar mass versus hydrodynamic radii (Rh) distributions of various debranched starches show that the debranching was not 100% and that the differences in the structure of various starches can be followed.
Co-reporter:Wouter M. J. Kloosterman;Gerda Spoelstra-van Dijk
Macromolecular Bioscience 2014 Volume 14( Issue 9) pp:1268-1279
Publication Date(Web):
DOI:10.1002/mabi.201400091
Novel 2-(β-maltooligooxy)-ethyl (meth)acrylate monomers are successfully synthesized by CGTase from Bacillus macerans catalyzed coupling of 2-(β-glucosyloxy)-ethyl acrylate and methacrylate with α-cyclodextrin or starch. HPLC-UV analysis shows that the CGTase catalyzed reaction yields 2-(β-maltooligooxy)-ethyl acrylates with 1 to 15 glucopyranosyl units. 1H NMR spectroscopy reveals that the β-linkage in the acceptor molecule is preserved during the CGTase catalyzed coupling reaction, whereas the newly introduced glucose units are attached by α-(1,4)-glycosidic linkages. The synthesized 2-(β-maltooligooxy)-ethyl acrylate monomers are successfully polymerized by aqueous free radical polymerization to yield the comb-shaped glycopolymer poly(2-(β-maltooligooxy)-ethyl acrylate).
Co-reporter:Rachmawati Rachmawati;Albert J. J. Woortman
Macromolecular Bioscience 2014 Volume 14( Issue 1) pp:56-68
Publication Date(Web):
DOI:10.1002/mabi.201300174
Highly crystalline amylose–polytetrahydrofuran (PTHF) complexes can be obtained by employing organic solvents as washing agents after complex formation. The X-ray diffraction (XRD) of the washed complexes appear sharp at 12.9°–13.2° and 19.6°–20.1°, clear signs of the presence of V6I-amylose. Other diffraction peaks correlate with V6II-amylose, which indicates that the complexed amylose helices are in the form of an intermediate or a mixture of V6I- and V6II-amylose. SEM imaging reveals that the amylose–PTHF complexes crystallize in the form of lamellae, which aggregate in a round shape on top of one another with a diameter around 4–8 μm. Some lamellas aggregate as flower-like or flat-surface spherulitic crystals. There is a visible matrix in between the aggregated lamellas which shows that a part of the amylose–PTHF complexes is amorphous.
Co-reporter:Laura Mazzocchetti;Theodoros Tsoufis;Petra Rudolf
Macromolecular Bioscience 2014 Volume 14( Issue 2) pp:186-194
Publication Date(Web):
DOI:10.1002/mabi.201300273
The successful synthesis of amylose brushes via enzymatic “grafting from” polymerization and the detailed characterization of all synthetic steps by X-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry measurements are reported. Au and Si surfaces are amino-functionalized with self-assembled monolayers (SAMs) of cystamine and 3-aminopropyldimethyethoxysilane (APDMES), respectively. Maltoheptaose is covalently attached to the amino-functionalized Au and Si surfaces via reductive amination. Amylose brushes are grown from maltoheptaose modified Au and Si surfaces with enzymatic polymerization using potato phosphorylase and Rabbit Muscle phosphorylase, as evidenced by spectroscopic ellipsometry and XPS measurements.
Co-reporter:Jelena Ciric;Dejan M. Petrovic
Macromolecular Chemistry and Physics 2014 Volume 215( Issue 10) pp:931-944
Publication Date(Web):
DOI:10.1002/macp.201300801
Starch, glycogen, and cellulose are all around us. They are eaten and used on a daily basis but they are not understood completely. Even though these carbohydrates are simple, concerning their repeating unit, they are hard to characterize. In order to try to understand as much as possible about their structure and the relationship between their molecular structure and physical properties, it is very practical to create such polysaccharides, for instance enzymatically, characterize them, and use them as standards for the characterization of natural ones. Therefore, the main objective of this Trend article is to outline different enzymatic routes to such carbohydrates, possibilities for their characterization, and the characterization of natural ones.
Co-reporter:Yi Jiang;Gert O. R. Alberda van Ekenstein;Albert J. J. Woortman
Macromolecular Chemistry and Physics 2014 Volume 215( Issue 22) pp:2185-2197
Publication Date(Web):
DOI:10.1002/macp.201400164
Co-reporter:Vincent S. D. Voet;Gerrit ten Brinke
Journal of Polymer Science Part A: Polymer Chemistry 2014 Volume 52( Issue 20) pp:2861-2877
Publication Date(Web):
DOI:10.1002/pola.27340
ABSTRACT
Poly(vinylidene fluoride) (PVDF) has reached the second largest production volume of fluoropolymers in recent years, and its popularity can be ascribed to high thermal stability and chemical inertness combined with its ferroelectric behavior. Copolymerization of vinylidene fluoride with other monomers leads to a wide variety of products with modified or improved properties. Besides commercially available fluorinated random copolymers, well-defined block-, graft, and alternating copolymers based on PVDF received more attention in recent years. PVDF-containing block copolymers that may self-assemble into well-ordered morphologies are of particular interest, being potential precursors for functional nanostructured materials applicable in membranes and electronics. This Highlight provides an overview of the routes developed towards these materials via conventional and controlled polymerization techniques. In addition, it discusses their nanoscopic phase behavior and current and potential applications. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2861–2877
Co-reporter:Wouter M. J. Kloosterman;Ser G. M. Brouwer ;Dr. Katja Loos
Chemistry – An Asian Journal 2014 Volume 9( Issue 8) pp:2156-2161
Publication Date(Web):
DOI:10.1002/asia.201402181
Abstract
Various cellulase preparations were found to catalyze the transglycosidation between cotton linters and 2-hydroxyethyl acrylate. The conversion and enzyme activity were found to be optimal in reaction mixtures that contained 5 vol % of the acrylate. The structures of the products were revealed by using TLC and 1H and 13C NMR spectroscopy. The enzyme-catalyzed reaction resulted in two products. The minor product originated from transglycosidation to hemicellulose and was found to be 2-(β-xylosyloxy)-ethyl acrylate. The major product was identified as 2-(β-glucosyloxy)-ethyl acrylate and the yield of the product was 5 wt % based on the amount of consumed cellulose. Glycosidation products with oligosaccharide moieties could not be detected in the reaction mixture. This result can be explained by the hydrolytic activities of the used cellulase preparation. Cellulase from Trichoderma reesei was found to possess, in addition to endoglucanase activity, cellobiosidase and β-glucosidase activities. Five other cellulase preparations from different origins were tested as well for catalysis of oligosaccharide acrylate synthesis. For most cellulase preparations the major transglycosidation product appeared to be 2-(β-glucosyloxy)-ethyl acrylate. Nevertheless, the endo-β-(1,4)-glucanase from Trichoderma longibrachiatum was found to catalyze the synthesis of 2-(β-cellobiosyloxy)-ethyl acrylate. Unlike the other cellulase preparations, endo-β-(1,4)-glucanase from T. longibrachiatum showed no detectable β-glucosidase activity and therefore oligosaccharide acrylate monomers were not further hydrolyzed into the monosaccharide acrylate 2-(β-glucosyloxy)-ethyl acrylate.
Co-reporter:E. Stavila, G. O. R. Alberda van Ekenstein, A. J. J. Woortman, and K. Loos
Biomacromolecules 2014 Volume 15(Issue 1) pp:
Publication Date(Web):December 2, 2013
DOI:10.1021/bm401514k
The enzymatic ring-opening copolymerization of ε-caprolactone (ε-CL) and β-lactam by using Candida antarctica lipase B (CAL-B) as catalyst was studied. Variation of the feed ratios of 25:75, 50:50, and 75:25 of ε-CL/β-lactam was performed. The products contain poly(ε-CL-co-β-lactam) and the homopolymers of poly(ε-CL) and poly(β-lactam). The structure of the copolymers was determined by MALDI-ToF MS. Poly(ε-CL-co-β-lactam) has an alternating and random structure consisting of alternating repeating units with oligo(ε-CL) or oligo(β-lactam). The highest fraction of the alternating copolymers resulted from the reaction with a feed ratio 50:50. The copolymer is a semicrystalline polymer with a Tm at 124 °C and Tgs at −15 and 50 °C. Interestingly, the copolymer also demonstrated cold crystallization at 29 and 74 °C, after quenching the sample from the melt in liquid nitrogen.
Co-reporter:Yi Jiang, Albert J. J. Woortman, Gert O. R. Alberda van Ekenstein, Dejan M. Petrović, and Katja Loos
Biomacromolecules 2014 Volume 15(Issue 7) pp:
Publication Date(Web):May 16, 2014
DOI:10.1021/bm500340w
2,5-Bis(hydroxymethyl)furan is a highly valuable biobased rigid diol resembling aromatic monomers in polyester synthesis. In this work, it was enzymatically polymerized with various diacid ethyl esters by Candida antarctica Lipase B (CALB) via a three-stage method. A series of novel biobased furan polyesters with number-average molecular weights (Mn) around 2000 g/mol were successfully obtained. The chemical structures and physical properties of 2,5-bis(hydroxymethyl)furan-based polyesters were fully characterized. Furthermore, we discussed the effects of the number of the methylene units in the dicarboxylic segments on the physical properties of the furan polyesters.
Co-reporter:Anton H. Hofman, Mehedi Reza, Janne Ruokolainen, Gerrit ten Brinke, and Katja Loos
Macromolecules 2014 Volume 47(Issue 17) pp:5913-5925
Publication Date(Web):August 21, 2014
DOI:10.1021/ma501257x
A double-comb diblock copolymer was constructed experimentally using a double supramolecular approach. Addition of 3-nonadecylphenol (3-NDP) amphiphiles to a symmetric, double hydrogen bond accepting poly(4-vinylpyridine)-block-poly(N-acryloylpiperidine) (P4VP-b-PAPI) diblock copolymer resulted in microphase separation on both the block copolymer and polymer–amphiphile level. Variation of the comb density x in these [P4VP-b-PAPI](3-NDP)x supramolecular complexes gave rise to several unique hierarchical nanostructures. For high comb densities (x = 0.8–1.2) double perpendicular lamellae-in-lamellae were observed, while lowering the density to x = 0.5 resulted in a double parallel lamellar morphology as demonstrated by small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). Further decreasing the concentration of 3-NDP (x = 0.3) caused the complex to self-assemble into cylinders-in-lamellae, while for x = 0.1 3-NDP only serves as a plasticizing agent. The phase transitions identified as a function of x are all in excellent agreement with our previously performed theoretical analysis.
Co-reporter:Jelena Ciric, Agnès Rolland-Sabaté, Sophie Guilois, Katja Loos
Polymer 2014 Volume 55(Issue 24) pp:6271-6277
Publication Date(Web):18 November 2014
DOI:10.1016/j.polymer.2014.09.059
•AF4 is a very powerful technique for the analysis of branched polysaccharides.•AF4 was successfully used for fractionation of various branched polysaccharides.•AF4 is especially suited for the characterization of high molecular weight polysaccharides in water.•The mechanism of the enzymatic reaction established via SEC analysis was confirmed.Asymmetrical flow field flow fractionation (AF4), when coupled with multi-angle laser light scattering (MALLS), is a very powerful technique for determination of the macromolecular structure of high molar mass (branched) polysaccharides. AF4 is a size fractionation technique just as size exclusion chromatography (SEC), nevertheless can overcome some crucial problems found in SEC analysis especially in starch like structures. This paper describes a detailed investigation of the macromolecular structure of two groups of well-defined synthetic amylopectin analogs – synthesized via an in vitro enzyme-catalyzed reaction using the enzymes phosphorylase b from rabbit muscle and Deinococcus geothermalis glycogen branching enzyme (Dg GBE). Size, molar mass distributions and structural data were studied by AF4 coupled with online quasi-elastic light scattering (QELS) and multi-angle light scattering (MALLS).
Co-reporter:Qiuyan Yang, Marcel H. de Vries, Francesco Picchioni and Katja Loos
Nanoscale 2013 vol. 5(Issue 21) pp:10420-10427
Publication Date(Web):29 Aug 2013
DOI:10.1039/C3NR81280D
In this study, we demonstrate a novel fabrication method to prepare metallic Janus silica particles by embedding nanosized silica particles on a spherical polystyrene (PS) substrate in supercritical carbon dioxide (sc CO2), followed by labelling with gold nanoparticles on the exposed part of the silica colloids. To this end, three main types of Janus particles displaying two distinct surfaces are produced by recovering silica from the polystyrene template. Embedment of particles into the PS template in sc CO2 allows for precise control of the degree of embedding of particles and subsequent modification of the partially exposed particle surface. The embedding degree, as well as the final Janus balance, can be varied over a wide range through control of pressure, temperature, or treatment time of sc CO2. Hierarchical PS–silica composites and embedment are evaluated by scanning electron microscopy (SEM). Partial surface modification with gold nanoparticles is investigated by transmission electron microscopy (TEM). With this method various functionalized Janus particles with tuneable properties can be prepared by adjusting various surface modifiers and polymer substrates in the future.
Co-reporter:Vincent S. D. Voet, Martijn Tichelaar, Stefania Tanase, Marjo C. Mittelmeijer-Hazeleger, Gerrit ten Brinke and Katja Loos
Nanoscale 2013 vol. 5(Issue 1) pp:184-192
Publication Date(Web):23 Oct 2012
DOI:10.1039/C2NR32990E
The fabrication of nanoporous poly(vinylidene fluoride) (PVDF) and PVDF/nickel nanocomposites from semicrystalline block copolymer precursors is reported. Polystyrene-block-poly(vinylidene fluoride)-block-polystyrene (PS-b-PVDF-b-PS) is prepared through functional benzoyl peroxide initiated polymerization of VDF, followed by atom transfer radical polymerization (ATRP) of styrene. The crystallization of PVDF plays a dominant role in the formation of the block copolymer structure, resulting in a spherulitic superstructure with an internal crystalline–amorphous lamellar nanostructure. The block copolymer promotes the formation of the ferroelectric β-polymorph of PVDF. Selective etching of the amorphous regions with nitric acid leads to nanoporous PVDF, which functions as a template for the generation of PVDF/Ni nanocomposites. The lamellar nanostructure and the β-crystalline phase are conserved during the etching procedure and electroless nickel deposition.
Co-reporter:Ivana Vukovic;Heiner Friedrich;Daniel Hermida Merino;Giuseppe Portale;Gerrit ten Brinke
Macromolecular Rapid Communications 2013 Volume 34( Issue 15) pp:1208-1212
Publication Date(Web):
DOI:10.1002/marc.201300326
Co-reporter:Jelena Ciric, Katja Loos
Carbohydrate Polymers 2013 Volume 93(Issue 1) pp:31-37
Publication Date(Web):1 March 2013
DOI:10.1016/j.carbpol.2012.04.008
An in vitro enzyme-catalyzed tandem reaction using the enzymes phosphorylase b from rabbit muscle and Deinococcus geothermalis glycogen branching enzyme (Dg GBE) to obtain branched polyglucans with tunable degree of branching (2% ÷ 13%) is presented. The tunable degree of branching is obtained by varying the reaction conditions such as pH value, the choice of reducing agent and its concentration and reaction time. Linear amylose is formed by the phosphorylase-catalyzed propagation of glucose-1-phosphate while Dg GBE introduces branching points on the α-(1 → 6) position by relocating short oligosaccharide chains. Our results show that the best way to obtain different degrees of branching with this set of enzymes is by regulation of the reaction time.Highlights► Branched polyglucans are synthesized by the use of enzymes from the transferase family. ► The synthesis results in branched polyglucans with tuneable degree of branching. ► Different degrees of branching are best regulated by the reaction time. ► The obtained polymers are pure and easily dissolve in water.
Co-reporter:S. Ahmadi-Abhari, A.J.J. Woortman, A.A.C.M. Oudhuis, R.J. Hamer, K. Loos
Carbohydrate Polymers 2013 Volume 97(Issue 2) pp:436-440
Publication Date(Web):12 September 2013
DOI:10.1016/j.carbpol.2013.04.095
•We study the influence of LPC on amylase susceptibility of wheat starch suspensions.•The influence of LPC on the starch degradation was examined at different concentrations.•LPC at high concentrations obviously decreased the digestibility of wheat starch.•Amylose-LPC inclusion complexes are rather stable even after a long term degradation.This study was aimed to assess the role of lysophosphatidylcholine (LPC) in the development of slowly digestible starch (SDS). The influence of LPC, on the enzymatic degradation of diluted 9% wheat starch suspensions (w/w) was investigated, using an in vitro digestion method. Wheat starch suspensions containing 0.5–5% LPC (based on starch) were heated in a Rapid Visco Analyser (RVA) till 95 °C and subjected to enzyme hydrolysis by porcine pancreatic α-amylase at 37 °C for several digestion periods. In vitro digestion measurements demonstrated that complexing starch with 5% LPC leads to a 22% decrease in rate of reducing sugar compared to the reference while the samples containing 0.5% LPC showed an equal digestibility comparable to the control. A clear decrease in the formation of reducing sugars was observed in presence of 2–5% LPC, since the results after 15 min digestion imply the formation of SDS due to the formation of amylose-LPC inclusion complexes. The DSC measurements proved the presence of amylose-LPC inclusion complexes even after 240 min digestion demonstrating the low susceptibility of amylose-V complexes to amylase.
Co-reporter:Rachmawati Rachmawati;Albert J. J. Woortman
Macromolecular Bioscience 2013 Volume 13( Issue 6) pp:767-776
Publication Date(Web):
DOI:10.1002/mabi.201300022
Co-reporter:S. Ahmadi-Abhari, A.J.J. Woortman, R.J. Hamer, A.A.C.M. Oudhuis, K. Loos
Carbohydrate Polymers 2013 Volume 93(Issue 1) pp:224-231
Publication Date(Web):1 March 2013
DOI:10.1016/j.carbpol.2012.05.020
Starch is an omnipresent constituent which is used for its nutritional and structuring properties. Recently concerns have been raised since starch is a source of readily available glucose which is tightly correlated with diabetes type II and obesity. For this reason, the possibilities for modulating the digestibility of starch while preserving its functional properties were investigated; therefore the focus of this paper is on starch gelatinization and the effect of lysophosphatidylcholine (LPC) on the structuring properties of wheat starch. The effect of LPC on thermal properties and viscosity behavior of starch suspensions was studied using DSC and RVA, respectively. The influence on granular structure was observed by light microscopy. The RVA profile demonstrated no viscosity increase at high LPC concentrations which proves intact granular structure after gelatinization. LPC in intermediate concentrations resulted in a notable delay of pasting; however the peak and end viscosities were influenced as well. Lower LPC concentrations demonstrated a higher peak viscosity as compared with pure starch suspensions. DSC results imply that inclusion complexes of amylose–LPC might be formed during pasting time. Since the viscosity profiles are changed by LPC addition, swelling power and solubility of starch granules are influenced as well. LPC hinders swelling power and solubility of starch granules which are stimulated by heating.Highlights► We study the influence of LPC on structural properties of wheat starch suspensions. ► The influence of LPC on the starch gelation was examined at different concentrations. ► LPC at low concentrations hinders swelling while preserving starch functionality. ► LPC at high concentrations blocks functional properties of wheat starch.
Co-reporter:S. Ahmadi-Abhari, A.J.J. Woortman, R.J. Hamer, K. Loos
Food Chemistry 2013 Volume 141(Issue 4) pp:4318-4323
Publication Date(Web):15 December 2013
DOI:10.1016/j.foodchem.2013.06.088
•We developed an in vitro digestion method usable for diluted starch suspensions.•The effect of amylose-LPC complexation on amylolysis of gelatinised starch was shown.•The method presents the molar mass distribution of starch molecules after digestion.•The effect of digestion time on molecular size distribution of the digesta was shown.•Amylose-LPC inclusion complexes decrease starch susceptibility to amylolytic enzymes.Amylose forms inclusion complexes with lysophosphatidylcholine (LPC), that decrease the susceptibility of amylose to amylase degradation. This study on the influence of complexation on starch susceptibility to amylase explains the nature of this protective effect. Wheat starch suspensions (9% w/w) containing 0.5–5% LPC were subjected to hydrolysis by porcine pancreatic α-amylase at 37 °C for several digestion times. The digesta were analysed by size-exclusion chromatography (SEC). The molar mass distribution was closely dependent on the digestion time and amount of LPC. This study precisely demonstrates the alteration of the digestion profile of starch on a molecular level, influenced by amylose-LPC complexation; however the effect depends on the digestion time. During 15 and 30 min digestion, inclusion complexes not only protect amylopectin in the initial hydrolysis stage, but also demonstrate lower susceptibility of the molecular amylose complexes to amylase hydrolysis. Digestion for 240 min resulted in a lower oligosaccharide peak concentration, in the presence of a high LPC concentration, which is related to less degradation of complexed amylose fraction.
Co-reporter:Vincent S. D. Voet, Daniel Hermida-Merino, Gerrit ten Brinke and Katja Loos
RSC Advances 2013 vol. 3(Issue 21) pp:7938-7946
Publication Date(Web):12 Apr 2013
DOI:10.1039/C3RA40365C
PVDF-based block copolymers have been employed as precursors for the construction of PVDF/PMAA/Ni nanocomposites. New poly(tert-butyl methacrylate)-block-poly(vinylidene fluoride)-block-poly(tert-butyl methacrylate) (PtBMA-b-PVDF-b-PtBMA) triblock copolymers were synthesized via atom transfer radical polymerization (ATRP) of tBMA from chlorine-terminated PVDF macroinitiators. The alternating crystalline–amorphous lamellar nanostructure and the spherulitic microstructure indicate the dominant role of crystallization of the PVDF segments during structure formation. The polar β-crystalline phase of PVDF has been detected within the block copolymer films. Hydrolysis of the tBMA segments and subsequent backfilling of the remaining polymer template with nickel through electroless metal deposition generated PVDF/PMAA/Ni nanocomposites. The β-polymorph was preserved during hydrolysis and electroless plating, as well as the lamellar morphology.
Co-reporter:E. Stavila, R.Z. Arsyi, D.M. Petrovic, K. Loos
European Polymer Journal 2013 Volume 49(Issue 4) pp:834-842
Publication Date(Web):April 2013
DOI:10.1016/j.eurpolymj.2012.12.010
Polyamides, or nylon, are widely used in fiber and engineering plastic materials, due to their good mechanical and thermal properties. Synthesis of oligomers from nylon-4,10, nylon-6,10, and nylon-8,10 were performed via polycondensation of diamines (1,4-butanediamine, 1,6-hexanediamine, and 1,8-diaminooctane) and diester (diethyl sebacate). These reactions were catalyzed by immobilized cutinase from Fusarium solani pisi on Lewatit beads, cutinase in the form of cross-linked enzyme aggregates (CLEA), or by immobilized Lipase B from Candida antarctica (N435). The highest maximal degree of polymerization (DPmax), up to 16, can be achieved in the synthesis of nylon-8,10 catalyzed by CLEA cutinase in diphenyl ether at 70 °C. By performing a reaction at cutinase optimal temperature (70 °C), CLEA cutinase in the synthesis of nylons shows good catalytic activity, like N435.Graphical abstractHighlights► Cutinase from Fusarium solani pisi was immobilized by adsorption on Lewatit beads or by cross-linked enzyme aggregates (CLEA). ► CLEA cutinase showed better catalytic activity then cutinase immobilized on Lewatit beads. ► Nylon-4,10, nylon-6,10, and nylon-8,10 oligomers are enzymatically polymerized. ► iCutinase on Lewatit, CLEA cutinase, and N435 showed better catalytic activity towards long chain diamines (C8 > C6 > C4).
Co-reporter:E. Stavila, K. Loos
Tetrahedron Letters 2013 Volume 54(Issue 5) pp:370-372
Publication Date(Web):30 January 2013
DOI:10.1016/j.tetlet.2012.10.133
The formation of ε-caprolactam from 6-aminocaproic acid catalyzed by CALB (N435) is reported. Different lactam ring sizes can be prepared starting from 4-aminobutanoic acid, 5-aminovaleric acid, and 8-aminooctanoic acid. Experiments with mixtures of aminocarboxylic acids have shown that CALB prefers homocyclization of the individual aminocarboxylic acids.
Co-reporter:Giuseppe Caroli
Macromolecular Chemistry and Physics 2013 Volume 214( Issue 22) pp:2602-2606
Publication Date(Web):
DOI:10.1002/macp.201300497
Co-reporter:Zheng Cao, Theodoros Tsoufis, Tiziana Svaldo-Lanero, Anne-Sophie Duwez, Petra Rudolf, and Katja Loos
Biomacromolecules 2013 Volume 14(Issue 10) pp:
Publication Date(Web):September 17, 2013
DOI:10.1021/bm4010904
Amylose brushes were synthesized by enzymatic polymerization with glucose-1-phosphate as monomer and rabbit muscle phosphorylase b as catalyst on gold-covered surfaces of a quartz crystal microbalance. Fourier transform infrared (FT-IR) spectra confirmed the presence of the characteristic absorption peaks of amylose between 3100 cm–1 and 3500 cm–1. The thickness of the amylose brushes—measured by Spectroscopic Ellipsometry—can be tailored from 4 to 20 nm, depending on the reaction time. The contour length of the stretched amylose chains on gold surfaces has been evaluated by single molecule force spectroscopy, and a total chain length of about 20 nm for 16.2 nm thick amylose brushes was estimated. X-ray photoelectron spectroscopy (XPS) was employed to characterize the amylose brushes before and after the adsorption of fatty acids. The dynamics of inclusion complex formation between amylose brushes and two fatty acids (octanoic acid and myristic acid) with different chain length was investigated as a function of time using a quartz crystal microbalance with dissipation monitoring (QCM-D) immersed in the liquid phase. QCM-D signals including the frequency and dissipation shifts elucidated the effects of the fatty acid concentration, the solvent types, the chain length of the fatty acids and the thickness of the amylose brushes on the dynamics of fatty acid molecule adsorption on the amylose brush-modified sensor surfaces.
Co-reporter:E. Stavila, G. O. R. Alberda van Ekenstein, and K. Loos
Biomacromolecules 2013 Volume 14(Issue 5) pp:
Publication Date(Web):April 1, 2013
DOI:10.1021/bm400243a
Enzymatically catalyzed polycondensation of p-xylylenediamine and diethyl sebacate resulted in oligo(p-xylylene sebacamide) with high melting temperatures (223–230 °C) and the enzymatic polycondensation of dimethyl terephthalate and 1,8-diaminooctane leads to oligo(octamethylene terephthalamide) with two melting temperatures at 186 and 218 °C. No oligoamides, but products 1 and 2, were formed from the enzymatic reaction of dimethyl terephthalate and p-xylylenediamine. All reactions were catalyzed by CAL-B, icutinase, or CLEA cutinase. All reactions catalyzed by CAL-B show higher conversion than reactions catalyzed by icutinase or CLEA cutinase. The highest DPmax of 15 was achieved in a one-step and two-step synthesis of oligo(p-xylylene sebacamide) catalyzed by CLEA cutinase.
Co-reporter:Rachmawati Rachmawati, Albert J. J. Woortman, and Katja Loos
Biomacromolecules 2013 Volume 14(Issue 2) pp:
Publication Date(Web):January 14, 2013
DOI:10.1021/bm301994u
Several methods were used to investigate the possibility of preparing inclusion complexes between amylose and polytetrahydrofurans (PTHF) via direct mixing. Potato amylose (Mv ∼ 200 kg/mol) and synthetic amylose (Mn 42 kg/mol) were complexed with PTHF having different molecular weights (Mn between 650 and 2900 g/mol) to study the effect of the length of the host and the guest molecules on the complexation. The resulted products were studied by differential scanning calorimetry (DSC) that showed a characteristic melting peak in the range of 120–140 °C. Emulsification of both amylose and polytetrahydrofuran improved the complexation. The largest amount of complexes was obtained with shorter PTHF chains, which also resulted in less amylose retrogradation. Furthermore, PTHF chains with similar molecular weight but different end groups were used. Amine terminated PTHF formed a higher amount of complexes compared to the hydroxyl terminated PTHF. However, no amylose complexes were formed using benzoyl terminated PTHF with low molecular weight. This is due to the bulky group of benzoyl, which indicates that the mechanism of the complexation between amylose and PTHF occurs via insertion rather than wrapping. In addition, X-ray diffraction (XRD) analysis showed that the included PTHFs induced the formation of the so-called V-amylose with six glucose residues per helix turn. Some additional diffraction peaks indicate that the induced V6-amylose is probably an intermediate or the mixtures between V6I- and V6II-amylose.
Co-reporter:Ivana Vukovic, Gerrit ten Brinke, Katja Loos
Polymer 2013 Volume 54(Issue 11) pp:2591-2605
Publication Date(Web):9 May 2013
DOI:10.1016/j.polymer.2013.03.013
3D nanostructured inorganic materials appear as promising candidates for various practical applications. Here we focus on metal nanofoams, a class of 3D nanomaterials uniquely combining the properties of metals and nanoporous materials, and review the recent developments in their preparation methods. Common approaches, such as dealloying, sol–gel synthesis, nanosmelting, combustion synthesis, etc., render metallic nanostructures with highly disordered architectures which might have adverse effects on their mechanical properties. In contrast, block copolymers have the ability to self-assemble into bicontinuous ordered nanostructures that can be applied as templates for the preparation of well-ordered metal nanofoams. Several examples of block copolymer template-directed synthesis of continuous metallic nanostructures will be described and the prospects of this approach will be discussed.Figure optionsDownload full-size imageDownload as PowerPoint slide
Co-reporter:Martin Faber, Anton H. Hofman, Evgeny Polushkin, Gert Alberda van Ekenstein, Jani Seitsonen, Janne Ruokolainen, Katja Loos, and Gerrit ten Brinke
Macromolecules 2013 Volume 46(Issue 2) pp:500-517
Publication Date(Web):January 4, 2013
DOI:10.1021/ma302295v
Hierarchical self-assembly of supramolecular double-comb diblock copolymer complexes, based on a diblock copolymer in which both blocks can participate in the hydrogen bonding with short amphiphiles, is discussed. A symmetric poly(4-vinylpyridine)-b-poly(N,N-dimethylacrylamide) (P4VP-b-PDMA) diblock copolymer was synthesized via reversible addition–fragmentation chain transfer (RAFT) polymerization. Supramolecular double-comb complexes were prepared by hydrogen bonding of 3-pentadecylphenol (PDP) to both blocks, as confirmed by infrared spectroscopy. The self-assembled structures were studied using small-angle X-ray scattering (SAXS), wide-angle X-ray scattering, and transmission electron microscopy (TEM). Self-assembly of the supramolecular complex containing a stoichiometric amount of PDP resulted in a lamellar-in-lamellar structure in which the large length scale is formed by the phase separation between the supramolecular blocks of the supramolecular complex. Both domains contain a smaller lamellar morphology of a different short length scale periodicity, orientated perpendicular with respect to the large length scale lamellar structure. Because of the difference in periodicity, the two short length scales can be distinguished clearly in SAXS and TEM.
Co-reporter:Kamlesh Kumar, Albert J. J. Woortman, and Katja Loos
Biomacromolecules 2013 Volume 14(Issue 6) pp:
Publication Date(Web):April 30, 2013
DOI:10.1021/bm400340k
The formation of amylose–polystyrene inclusion complexes via a novel two-step approach is described. In the first-step, styrene was inserted inside the amylose helical cavity, followed by free radical polymerization in the second step. The inclusion complexes were characterized by attenuated total reflection fourier transform infrared spectroscopy (ATR-FTIR), ultraviolet spectroscopy (UV), X-ray diffraction (XRD), atomic force microscopy (AFM), and differential scanning calorimetry (DSC). The formation of polystyrene was confirmed by gel permeation chromatography (GPC). The molecular weight of polystyrene can be varied by using amylose bearing different molar masses. The approach described here is general and could be used to synthesize other host–polymer inclusion complexes for which long chains of polymeric guests are difficult to insert into the host cavity.
Co-reporter:Jelena Ciric, Jorrit Oostland, Jan Willem de Vries, Albert J. J. Woortman, and Katja Loos
Analytical Chemistry 2012 Volume 84(Issue 23) pp:10463
Publication Date(Web):November 4, 2012
DOI:10.1021/ac302704q
Determination of the size distributions of natural polysaccharides is a challenging task. More advantageous for characterization are well-defined synthetic (hyper)-branched polymers. In this study we concentrated on synthetic amylopectin analogues in order to obtain and compare all available data for different distributions and size dependence of molecular weights. Two groups of well-defined synthetic branched polysaccharides were synthesized via an in vitro enzyme-catalyzed reaction using the enzyme phosphorylase b from rabbit muscle and Deinococcus geothermalis glycogen branching enzyme. Synthetic polymers had a tunable degree of branching (2%–13% determined via 1H NMR) and a tunable degree of polymerization (30–350 determined indirectly via UV spectrometry). The systems used for separation and characterization of branched polysaccharides were SEC-DMSO/LiBr and multi detection (refractive index detector, viscosity detector, and multi angle light scattering detector) and SEC-water/0.02% NaN3; and SEC-50 mM NaNO3/0.02% NaN3 and multi detection. Additionally the side chain length distribution of enzymatically debranched polysaccharides was investigated by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) analysis. With this combination of characterization techniques, we were able not only to characterize the amylopectin analogues but also to solve parts of the molecular mechanism of their enzymatic polymerization. Moreover our materials showed potential to be standards in the field of natural polysaccharides characterization.
Co-reporter:Martin Faber, Vincent S. D. Voet, Gerrit ten Brinke and Katja Loos
Soft Matter 2012 vol. 8(Issue 16) pp:4479-4485
Publication Date(Web):06 Mar 2012
DOI:10.1039/C2SM07211D
A-b-(B-b-A)n-b-B multiblock copolymers composed of short middle diblock units (B-b-A)n and two long A- and B-outer blocks were successfully prepared. The multiblock copolymers consist of polystyrene (S) and poly(p-hydroxystyrene) (pHS) and were prepared through sequential anionic polymerization of styrene and 4-tert-butoxystyrene, followed by hydrolysis of the tert-butoxy group. A hexablock and an octablock copolymer with a low overall polydispersity were synthesized. The self-assembled structures were investigated using Small Angle X-ray Scattering (SAXS) and Transmission Electron Microscopy (TEM). Due to the smaller number of inner blocks and their relatively small molar mass, a single periodic lamellar morphology was observed for the hexablock copolymer while a lamellar-in-lamellar morphology with two thin layers within successive thick layers was observed for the octablock copolymer with larger middle diblock units. These observations are in excellent agreement with existing theories.
Co-reporter:Ivana Vukovic, Gerrit ten Brinke, and Katja Loos
Macromolecules 2012 Volume 45(Issue 23) pp:9409-9418
Publication Date(Web):November 28, 2012
DOI:10.1021/ma301974z
Supramolecular complexes of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) diblock copolymers and small molecules such as pentadecylphenol (PDP) have been studied extensively in recent years. In the present study, PS-b-P4VP(PDP) complexes with a minority P4VP(PDP) block are morphologically characterized focusing on the region between the lamellar and cylindrical phase. Dynamic mechanical measurements and small-angle X-ray scattering are used to follow the transitions between the ordered states upon heating/cooling. The self-assembled state at various temperatures is determined by small-angle X-ray scattering and transmission electron microscopy. In contrast to the opposite case of majority P4VP(PDP) blocks, where the transition from lamellar to cylindrical structures frequently occurs via the gyroid morphology, the complexes adopt the hexagonally perforated layered morphology in a broad range of compositions. Although known as a metastable phase in pure diblock copolymers, the hexagonally perforated layered phase appears as an equilibrium phase in PS-b-P4VP(PDP) complexes, being stabilized by the presence of the hydrogen-bonded PDP side chains in the minority component domains.
Co-reporter:Ivana Vukovic, Thomas P. Voortman, Daniel Hermida Merino, Giuseppe Portale, Panu Hiekkataipale, Janne Ruokolainen, Gerrit ten Brinke, and Katja Loos
Macromolecules 2012 Volume 45(Issue 8) pp:3503-3512
Publication Date(Web):April 6, 2012
DOI:10.1021/ma300273f
The double gyroid network morphology has been the focus of extensive research efforts as one of the most appealing block copolymer structures for practical applications. We performed an extensive study of the phase behavior of the supramolecular complex PS-b-P4VP(PDP)x to develop a systematic route to its double gyroid morphology. The morphological characterization of complexes was accomplished by transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS). Several compositions with the cubic Ia3̅d symmetry were found in a narrow region between the lamellar and the cylindrical phase. Experimental TEM images were compared to computer simulations of projections through multiple gyroid planes. Typical gyroid patterns—“double wave” and “wagon wheel”—were regularly found. The size of the gyroid unit cell was calculated from the SAXS data. The lattice parameter could be varied (from ca. 70 to 125 nm) by altering the molar mass of the block copolymer precursors. A number of complexes were found to exhibit characteristic biphasic morphologies—coexisting lamellar and gyroid phase or gyroid and cylindrical phase. Finally, gyroid complexes with different relative PDP ratios were obtained which provides the opportunity to generate nanoporous structures with tunable porosities by dissolving the amphiphiles.
Co-reporter:Gerrit Gobius du Sart;Ivana Vukovic;Zorica Vukovic;Evgeny Polushkin;Panu Hiekkataipale;Janne Ruokolainen;Gerrit ten Brinke
Macromolecular Rapid Communications 2011 Volume 32( Issue 4) pp:366-370
Publication Date(Web):
DOI:10.1002/marc.201000674
Co-reporter:Gerrit Gobius du Sart;Ivana Vukovic;Zorica Vukovic;Evgeny Polushkin;Panu Hiekkataipale;Janne Ruokolainen;Gerrit ten Brinke
Macromolecular Rapid Communications 2011 Volume 32( Issue 4) pp:
Publication Date(Web):
DOI:10.1002/marc.201190008
Co-reporter:Nemanja Mileti&x107;;Zorica Vukovi&x107;;Aleksra Nastasovi&x107;
Macromolecular Bioscience 2011 Volume 11( Issue 11) pp:1537-1543
Publication Date(Web):
DOI:10.1002/mabi.201100127
Co-reporter:Ivana Vukovic, Sergey Punzhin, Zorica Vukovic, Patrick Onck, Jeff Th. M. De Hosson, Gerrit ten Brinke, and Katja Loos
ACS Nano 2011 Volume 5(Issue 8) pp:6339
Publication Date(Web):July 8, 2011
DOI:10.1021/nn201421y
Metal nanofoams with a porosity above 50% v/v have recently attracted great interest in materials science due to their interesting properties. We demonstrate a new straightforward route to prepare such nanofoams using diblock copolymer-based PS-block-P4VP(PDP) supramolecules that self-assemble into a bicontinuous gyroid morphology, consisting of PS network channels in a P4VP(PDP) matrix. After dissolving the PDP, the P4VP collapses onto the PS struts and a free-standing bicontinuous gyroid template of 50–100 μm thickness and interconnected, uniformly sized pores is formed. The hydrophilic P4VP corona facilitates the penetration of water-based plating reagents into the porous template and enables a successful metal deposition. After plating, the polymer is simply degraded by heating, resulting in a well-ordered inverse gyroid nickel foam. Essential to this approach is the removal of only one part of the matrix (i.e., PDP). Therefore, the template accounts for 50% v/v or more. The porosity characteristics (amount, size of pores) can be tuned by selecting the appropriate copolymer and by adjusting the amount of PDP.Keywords: diblock copolymers; metal nanofoams; metal plating; nanopores; supramolecules
Co-reporter:Jeroen van der Vlist, Iris Schönen, and Katja Loos
Biomacromolecules 2011 Volume 12(Issue 10) pp:
Publication Date(Web):September 2, 2011
DOI:10.1021/bm2009763
Densely packed polysaccharide brushes consisting of α-d-glucose residues were grafted from modified silicon substrates. Potato phosphorylase was herein used to grow linear polysaccharide chains from silicon tethered maltoheptaose oligosaccharides using glucose-1-phosphate as donor substrate. The combined use of potato phosphorylase and Deinococcusgeothermalis branching enzyme resulted in a hyperbranched brush coating as the latter one redistributes short oligosaccharides from the α(1–4)-linked position to the α (1–6)-linked position in the polysaccharide brush. The obtained grafting density of the brushes was estimated on 1.89 nm–2 while the thickness was measured with ellipsometric techniques and determined to be between 12.2 and 20.2 nm.
Co-reporter:Nemanja Mileti&x107;;Volker Abetz;Katrin Ebert
Macromolecular Rapid Communications 2010 Volume 31( Issue 1) pp:71-74
Publication Date(Web):
DOI:10.1002/marc.200900497
Co-reporter:Nemanja Mileti&x107;;Volker Abetz;Katrin Ebert
Macromolecular Rapid Communications 2010 Volume 31( Issue 1) pp:
Publication Date(Web):
DOI:10.1002/marc.200990066
Co-reporter:Gerrit Gobius du Sart, Ivana Vukovic, Gert Alberda van Ekenstein, Evgeny Polushkin, Katja Loos and Gerrit ten Brinke
Macromolecules 2010 Volume 43(Issue 6) pp:2970-2980
Publication Date(Web):February 18, 2010
DOI:10.1021/ma902651t
Four different poly(tert-butoxystyrene)-b-polystyrene-b-poly(4-vinylpyridine) (PtBOS-b-PS-b-P4VP) linear triblock copolymers, with the P4VP weight fraction varying from 0.08 to 0.39, were synthesized via sequential anionic polymerization. The values of the unknown interaction parameters between styrene and tert-butoxystyrene and between tert-butoxystyrene and 4-vinylpyridine were determined from random copolymer blend miscibility studies and found to satisfy 0.031 < χS,tBOS < 0.034 and 0.39 < χ4VP,tBOS <0.43, the latter being slightly larger than the known 0.30 < χS,4VP ≤ 0.35 value range. All triblock copolymers synthesized adopted a P4VP/PS core/shell cylindrical self-assembled morphology. From these four triblock copolymers supramolecular complexes were prepared by hydrogen bonding a stoichiometric amount of pentadecylphenol (PDP) to the P4VP blocks. Three of these complexes formed a triple lamellar ordered state with additional short length scale ordering inside the P4VP(PDP) layers. The self-assembled state of the supramolecular complex based on the triblock copolymer with the largest fraction of P4VP consisted of alternating layers of PtBOS and P4VP(PDP) layers with PS cylinders inside the latter layers. The difference in morphology between the triblock copolymers and the supramolecular complexes is due to two effects: (i) a change in effective composition and, (ii) a reduction in interfacial tension between the PS and P4VP containing domains. The small angle X-ray scattering patterns of the supramolecules systems are very temperature sensitive. A striking feature is the disappearance of the first order scattering peak of the triple lamellar state in certain temperature intervals, while the higher order peaks (including the third order) remain. This is argued to be due to the thermal sensitivity of the hydrogen bonding and thus directly related to the very nature of these systems.
Co-reporter:Nemanja Miletić, Randi Rohandi, Zorica Vuković, Aleksandra Nastasović, Katja Loos
Reactive and Functional Polymers 2009 69(1) pp: 68-75
Publication Date(Web):1 January 2009
DOI:10.1016/j.reactfunctpolym.2008.11.001
Crosslinked macroporous hydrophilic poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) [abbreviated poly(GMA-co-EGDMA)] with identical chemical structure (60% of glycidyl methacrylate) but with varied average pore sizes (from 30 to 560 nm), specific surface areas (from 13.2 to 106.0 m2/g), specific volumes (from 0.755 to 1.191 cm3/g) and particle sizes (<100 μm–630 μm) were synthesized via suspension polymerization. Modifications of poly(GMA-co-EGDMA) with various diamines (1,2-diaminoethane, 1,4-diaminobutane, 1,6-diaminohexane and 1,8-diaminooctane), 2-fluoroethylamine, glutaraldehyde and cyanuric chloride were carried out. The influence of the interaction between Candida antarctica lipase B (Cal-B) and various carriers during immobilization on the loading and hydrolytic activity (hydrolysis of para-nitrophenyl acetate) of the immobilized Cal-B were studied. Immobilization of Cal-B was performed at different temperatures and pH values. Cal-B immobilized at 30 °C and pH 6.8 was leading to increased activities. Purely physical adsorption between enzyme and copolymer was observed on carriers in which amine or fluorine groups were introduced into the carrier structure by modification with various diamines or 2-fluoroethylamine. As a consequence enzyme loading and activity decreases. In contrary, modification of the poly(GMA-co-EGDMA) with glutaraldehyde and cyanuric chloride results in a covalent connection between enzyme and carrier. The obtained results show a significant increase in Cal-B activity. The influence of the amount of glutaraldehyde and cyanuric chloride used for modification was screened. Increasing the amount of glutaraldehyde or cyanuric chloride used for modification resulted in an increase of the enzyme loading. Consequently, higher amount of glutaraldehyde used led to a higher fraction of the enzyme molecules that are covalently connected on to the carrier. As the amount of glutaraldehyde or cyanuric chloride used for modifications increases, activity of immobilized C. antarctica lipase B primarily increases, showing the highest value for 0.66% and 0.050% w/w, respectively, and subsequently decreases. We could show that Cal-B immobilized on epoxy-containing copolymer modified with glutaraldehyde and cyanuric chloride performs higher activity than free enzyme powder.
Co-reporter:Jeroen van der Vlist;Marta Palomo Reixach;Marc van der Maarel;Lubbert Dijkhuizen;Arend Jan Schouten
Macromolecular Rapid Communications 2008 Volume 29( Issue 15) pp:1293-1297
Publication Date(Web):
DOI:10.1002/marc.200800248
Co-reporter:Gerrit Gobius du Sart, Rachmawati Rachmawati, Vincent Voet, Gert Alberda van Ekenstein, Evgeny Polushkin, Gerrit ten Brinke and Katja Loos
Macromolecules 2008 Volume 41(Issue 17) pp:6393-6399
Publication Date(Web):August 15, 2008
DOI:10.1021/ma800147e
Using atom transfer radical polymerization (ATRP), poly(tert-butyl methacrylate-b-styrene-b-4-vinylpyridine) or PtBMA-b-PS-b-P4VP linear triblock copolymers were synthesized. Different homopolymer and diblock copolymer macroinitiators were used for different block copolymerizations. For a selected triblock copolymer the self-assembly was studied with transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS), and thermal analysis. Indications were found for a core−shell hexagonal ordering of coaxial cylinders with P4VP cylinders separated from the PtBMA matrix phase by a PS shell layer. To further support this, the interaction parameter between styrene and tBMA was investigated by a random copolymer blend miscibility study on blends of P(S-co-tBMA) random copolymers with PS and found to satisfy 0.08 < χS,tBMA < 0.10.
Co-reporter:Jeroen van der Vlist
Macromolecular Symposia 2007 Volume 254(Issue 1) pp:54-61
Publication Date(Web):10 AUG 2007
DOI:10.1002/masy.200750808
Summary: Oligo- and polysaccharides are important macromolecules in living systems, showing their multifunctional characteristics in the construction of cell walls, energy storage, cell recognition and their immune response.
Saccharides as organic raw materials can open new perspectives on the way to new biocompatible and biodegradable products which could help to overcome the problems resulting from the upcoming restrictions of petrochemical resources. Construction of well-defined carbohydrate polymer backbones is very challenging as it is difficult to realize complete regio and stereo-control of the glycosylating process. Most synthetic approaches are therefore based on the modification or degradation of naturally occurring polysaccharides resulting in less then perfect products. Enzymes have several remarkable catalytic properties compared with other types of catalysts in terms of their selectivity, high catalytic activity, lack of undesirable side reactions and operation under mild conditions. A biocatalytic pathway to synthesize saccharides is therefore very attractive as it results in well-defined polysaccharides avoiding the above drawbacks.
When biogenic polysaccharides are combined with synthetic macromolecules, surfaces etc. materials with new interesting properties arise and the processability of the designed hybrid materials is facilitated. Amylose and amylopectin hybrid materials can be synthesized via enzymatic polymerization routes utilizing transferases. This approach opens access to well-defined hybrid structures bearing amylase or amylopectin moieties that cannot be synthesized by any other means.
Co-reporter:Nemanja Miletić, Zorica Vuković, Aleksandra Nastasović, Katja Loos
Journal of Molecular Catalysis B: Enzymatic (April 2009) Volume 56(Issue 4) pp:196-201
Publication Date(Web):1 April 2009
DOI:10.1016/j.molcatb.2008.04.012
Crosslinked macroporous hydrophilic poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate)s [abbreviated poly(GMA-co-EGDMA)] with identical chemical structure (60% of glycidyl methacrylate) but with varied average pore sizes (from 30 to 560 nm), specific surface areas (from 13.2 to 106.0 m2/g), specific volumes (from 0.755 to 1.191 cm3/g) and particle sizes (less than 100–650 μm) were synthesized via suspension polymerization. The influence of the resin properties on the loading of Candida antarctica lipase B (Cal-B) during immobilization and on the hydrolytic (hydrolysis of para-nitrophenyl acetate) and synthetic (ring-opening polymerization of ɛ-caprolactone) activity of the immobilized Cal-B were studied. Immobilization of Cal-B was performed at different temperatures and pH values. Cal-B immobilized at 30 °C and pH 6.8 was leading to increased activities. By decreasing the resin diameter: (i) the amount of Cal-B adsorbed onto the resin decreases, (ii) the conversion of para-nitrophenyl acetate increases (hydrolytic activity) and (iii) the conversion of ɛ-caprolactone and the molecular weight of the synthesized poly-ɛ-caprolactone increases (synthetic activity). Varying the porosity parameters results in different hydrolytic and synthetic activities. Pore sizes of all synthesized resins (from 30 to 560 nm) are big enough to overcome diffusion limitations. Therefore increasing the pore size of the resins resulted in a large increase in the hydrolytic and synthetic activity. Increasing the specific surface area resulted in an increase of activities, as the result of alleviated substrate approach to the immobilized enzyme zones. The obtained results were compared to results from dried Cal-B powder and Novozyme 435. Resin with particle size less than 100 μm and pore size 48 nm had much higher hydrolytic activity than both dried Cal-B powder and Novozyme 435. Nearly similar trends were observed for the synthetic activity.Via the DMSO leaching technique we could show that about 80% of Cal-B was covalently attached to the macroporous resin.
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