Co-reporter:Qianqian Wang, Siyu Chen, Dajun Chen
Journal of the Mechanical Behavior of Biomedical Materials 2017 Volume 65() pp:466-477
Publication Date(Web):January 2017
DOI:10.1016/j.jmbbm.2016.09.009
•Chitin nano-whiskers (CNWs) were prepared and introduced to enhance an injectable system.•Composite hydrogel showed great mechanical properties, biological compatibility and fast gelation speed.•CNWs worked as an effective cross-linker.•Mechanical property was influenced by both CNWs content and gelation temperature.The objective of current study was to prepare an injectable hydrogel with great mechanical properties and biological compatibility, which could be more suitable to be applied as tissue engineering scaffold. Chitin nano-whiskers (CNWs) were introduced into chitosan/β-glycerophosphate disodium salt (CS/GP) injectable hydrogel. The effects of CNWs contents and gelation temperatures on gelation speed and mechanical properties of the composite hydrogels were characterized and discussed. The maximum values of tensile strength and elongation at break were both more than 4 times larger than that of neat CS/GP hydrogel. The gelation time of injectable hydrogel with 5% CNWs content (formed at 37 °C) was 25 seconds, which was much shorter than that (6038 seconds) of the neat CS/GP hydrogel. In combination with results of Fourier transform infrared spectroscopy (FT-IR), it was proved that CNWs functioned as a cross-linker through hydrogen bond interaction in the gel formation process, which might be the main reason for mechanical enhancement. Meanwhile, gels formed with higher CNWs content and gelation temperature had lower equilibrium swelling ratio and drug release rate. Cytotoxicity of hydrogel in vitro was studied by MTT method with a result of indicating a good biocompatibility of CNWs enhanced hydrogel.
Co-reporter:Yekai Zhu, Dajun Chen
Materials & Design 2017 Volume 113(Volume 113) pp:
Publication Date(Web):5 January 2017
DOI:10.1016/j.matdes.2016.10.016
•Attapulgite-based nanofibrous membranes were fabricated via a papermaking procedure.•A “woodpile” structure model was proposed for the nanofibrous membranes.•The nanofibrous membranes showed high tensile strength, excellent flexibility, high porosity and low pore size.•The rejection of the membrane for oil/water emulsion was nearly 100%.Inspired by the woodpile and irregular entanglement phenomenon, attapulgite (AT)-based nanofibrous membranes (NFMs) with different poly(vinyl alcohol) (PVA) contents were fabricated via a facile method consisting of pulping, handsheet making and low temperature drying process. In this study, the dispersion state and rheological behavior of AT with different PVA contents were studied. A “woodpile” structure of AT-based NFMs was proposed and discussed. AT-based NFMs showed high porosity (above 50%), high tensile strength (12.5 MPa) and elongation at break (1.9%). Furthermore, the optimized AT-9 exhibited low pore size (around 10 nm), good hydrophilicity (contact angle, 31.3°), high pure water flux (105 L m− 2 h− 1 bar− 1) and high rejection (0.1 MPa, 99.4%) for oil/water emulsion, suggesting a promising candidate for wastewater treatment applications. This work also provides a new insight into the design and development of inorganic-based NFMs.Download high-res image (117KB)Download full-size image
Co-reporter:Zhicheng Yuan, Ye Lan, Siyu Chen, Dajun Chen
Applied Clay Science 2017 Volume 147(Volume 147) pp:
Publication Date(Web):1 October 2017
DOI:10.1016/j.clay.2017.07.029
•Magnetically recyclable nano-composite palygorskite photocatalyst is prepared.•The palygorskite can help decrease the aggregation of the macrocycles.•The photocatalyst is effectively separated under an external magnetic field.•The magnetic palygorskite also improves the photocatalytic activity.Novel magnetically recyclable nano-composite photocatalyst (AT/Fe3O4-FeOCAP) was successfully prepared from Fe-octacarboxylic acid phthalocyanine (FeOCAP) and magnetic palygorskite nanoparticle (AT/Fe3O4) by an ultrasonic method. The structure characterizations of the photocatalyst were carried out by Fourier transform infrared spectroscopy (FT-IR), Ultraviolet-visible spectra (UV–Vis), Vibrating sample magnetometer (VSM) and X-ray photoelectron spectroscopy (XPS). Moreover, the photocatalytic degradation properties and reusability of the photocatalyst were evaluated using Rhodamine B (RhB) as a model compound. The results of FT-IR, UV–Vis and XPS showed the FeOCAP was successfully introduced onto the surface of the AT/Fe3O4. The nano-composite photocatalyst showed excellent superparamagnetic property, and therefore, could be effectively separated by simply applying an external magnetic field. Photocatalytic activity studies confirmed that the as-prepared photocatalyst had excellent RhB photodegradation property. The degradation percentage of RhB was about 95.6%. The degradation kinetics could be described by the Langmuir-Hinshelwood kinetic model.Download high-res image (83KB)Download full-size image
Co-reporter:Yurun Xu, Dajun Chen
Materials Chemistry and Physics 2017 Volume 195(Volume 195) pp:
Publication Date(Web):1 July 2017
DOI:10.1016/j.matchemphys.2017.04.007
•Composites with both self-healing and enhanced mechanical property are prepared.•Healing mechanism relies on disulfide exchange reaction and shape memory effect.•Mechanical enhancement is caused by rich hydrogen bonds introduced by attapulgite.Nanocomposites with remarkable enhanced mechanical properties have attracted great research efforts recently. In this work, a series of self-healing polyurethane/attapulgite nanocomposites were prepared by solution blending. Introducing self-healing ability and attapulgite (AT) reinforcement simultaneously led to prolonged material lifetime and enhanced mechanical properties. Scanning electron microscope (SEM) observation indicated that AT could achieve a uniform dispersion in polyurethane matrix when AT content was relatively low. The influences on mechanical properties were evaluated by tensile test. Results showed that incorporating an appropriate content of AT would lead to an enhanced tensile properties. The interactions between AT and polyurethane matrix were studied by effective cross-linking density calculation and Fourier transform infrared (FTIR) analysis. Results indicated that rich hydrogen bonds were formed between AT and polyurethane matrix. Displacement data was utilized to evaluate the influence on shape memory effect. With the incorporation of AT, deformation of the sample under external force was restrained. Meanwhile, closure of the scratches still can be accomplished during healing process. Results of healing test suggested that incorporating 1% of AT would also promote self-healing property.Download high-res image (205KB)Download full-size image
Co-reporter:Ting Wan
Journal of Materials Science 2017 Volume 52( Issue 1) pp:197-207
Publication Date(Web):2017 January
DOI:10.1007/s10853-016-0321-x
Materials with intrinsic self-healing ability have attracted tremendous interest in literature, especially coatings in anti-corrosion applications. In this work, environmentally friendly waterborne polyurethanes containing disulfide bonds in the main chain were synthesized. Poly (ε-caprolactone) glycol with a molecular weight of 1000 was used as soft segment, and isophorone diisocyanate, 2-bis(hydroxymethyl) propionic acid, and 2-hydroxyethyl disulfide were used as hard segment. The influence of 2-hydroxyethyl disulfide/2-bis(hydroxymethyl) propionic acid molar ratios on stability of dispersions and the self-healing property of the waterborne polyurethane films was investigated. The self-healing system was triggered by the chain exchange reaction of disulfide bonds and assisted by the shape memory effect to bring the crack on the waterborne polyurethane surfaces in spatial proximity. The tensile strength of the scratched waterborne polyurethane film was recovered to 90.5 % in 10 min at a modest healing temperature of 65 °C. Meanwhile, the prepared waterborne polyurethanes exhibited excellent dispersion stability and improved thermal stability.
Co-reporter:Ting Wan, Dajun Chen, Xue Bai
Dyes and Pigments 2016 Volume 129() pp:18-23
Publication Date(Web):June 2016
DOI:10.1016/j.dyepig.2016.02.011
•An environmental friendly method to dye polyurethane was proposed.•The dope-dyed polyurethane films had good dye fastness.•The mechanical and thermal properties of composite films were improved.•The dope-dyeing solution had a pseudo-plastic non-Newtonian behavior.In this paper, dope dyeing method was adopted in preparation of polyurethane/β-cyclodextrin/disperse orange 31 solutions. The solutions were cast into films. Characterizations of the structure and properties of films were investigated by FTIR, UV–vis spectra, mechanical test, DMA and TGA. The results revealed that the dope-dyed polyurethanes had good dye fastness, increased mechanical and thermal properties, which could be ascribed to the existence of hydrogen bonding between β-CD and polyurethane. The results of rheological measurements showed that the dope-dyeing solution had a pseudo-plastic non-Newtonian behavior and the non-Newtonian Index increased with increasing of temperature.
Co-reporter:Jianru Wu, Dajun Chen
Progress in Organic Coatings 2016 Volume 97() pp:203-209
Publication Date(Web):August 2016
DOI:10.1016/j.porgcoat.2016.04.033
•In this paper, liquefiable dimethylol propionic acid (LDMPA) was designed by the condensation of ε-caprolactone(CL) with dimethylol propionic acid (DMPA).•A series of waterborne polyurethanes (WPU) were successfully synthesized by using LDMPA.•The structure and properties of the WPU were studied.•The influence of LDMPA on the properties of WPU was investigated, while WPU synthesized by using DMPA was used as a comparison.In this paper, a low temperature liquefiable dimethylol propionic acid (LDMPA) was designed by the condensation of ε-caprolactone(CL) with dimethylol propionic acid (DMPA). A series of waterborne polyurethanes were successfully synthesized by using LDMPA. The structure and properties of the waterborne polyurethanes were characterized by IR, particle size analysis and tensile tests. It was found that with increasing LDMPA content, the particle size of the waterborne polyurethane emulsion decreased. The results of tensile tests showed that with increasing LDMPA content, the tensile strength and elongation at break of the samples increased at first and then deceased. DMA results showed that compared with samples using dimethylol propionic acid (DMPA), the introduction of LDMPA into WPU chain could reduce waterborne polyurethane’s micro-phase separation degree.
Co-reporter:Yang Ti;Qiang Wen
Journal of Applied Polymer Science 2016 Volume 133( Issue 9) pp:
Publication Date(Web):
DOI:10.1002/app.43069
ABSTRACT
In this article, thermoplastic polyurethane (TPU)/attapulgite (AT) nanocomposites were prepared by solution blending. The interaction between AT and TPU was investigated by Fourier transform infrared (FTIR) and dynamic mechanical analysis (DMA). The carbonyl stretching region (1680–1760 cm−1) of infrared spectra was studied to investigate the difference of the hydrogen bonding degree of the samples. The degree of hydrogen-bonded carbonyl groups of the samples were found to be increased with increasing AT content and decreased with increasing temperature. The equilibrium between free and hydrogen-bonded carbonyl groups was discussed. The values of dissociation enthalpy of the hydrogen-bonded carbonyl groups increased with increasing AT content. Quantitative evaluations of the interaction between AT and TPU was conducted by analyzing the physical cross-links density of the samples. The results indicated that the physical cross-links density of the samples increased with increasing AT content. The results of tensile tests showed that with increasing AT content, the mechanical properties of the samples increased, which confirmed that strong interaction was formed between AT and TPU matrix. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43069.
Co-reporter:Yurun Xu
Macromolecular Chemistry and Physics 2016 Volume 217( Issue 10) pp:1191-1196
Publication Date(Web):
DOI:10.1002/macp.201600011
Co-reporter:Yang Ti
Journal of Applied Polymer Science 2015 Volume 132( Issue 3) pp:
Publication Date(Web):
DOI:10.1002/app.41284
ABSTRACT
In this article, Fe-Tetranitro phthalocyanine (Fe-TNPc)/polyurethane (PU) blends were prepared by solution blending. The mechanical properties of the samples were studied by tensile tests. The results showed that the tensile strength and the elongation at break of the samples increased with increasing Fe-TNPc content. The improved mechanical properties for the samples containing Fe-TNPc was attributed to the increased microphase separation degree of PU, which was further investigated by dynamic mechanical analysis (DMA) and Fourier transform infrared analysis. The lower Tg of the soft segments and the higher Tg of the hard segments for the samples containing Fe-TNPc indicated an increase of microphase separation degree of PU. The increased hydrogen bonded carbonyl groups in the samples with increasing Fe-TNPc content also proved the conclusion. Quantitative evaluation of the interaction between Fe-TNPc and PU was also investigated by analyzing the physical crosslinking density of the samples. The results indicated that the physical crosslinking density of the samples increased with increasing Fe-TNPc content. The antibacterial properties of the samples were investigated. The results showed that the percentage bacterial inactivation toward S. aureus and E. coli of the samples were 98.9% and 90.9%, respectively, when Fe-TNPc was added to 1%. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41284.
Co-reporter:Zhicheng Yuan;Yang Wang;Xiao Han
Journal of Applied Polymer Science 2015 Volume 132( Issue 28) pp:
Publication Date(Web):
DOI:10.1002/app.42244
ABSTRACT
In this article, the multiple stimulus-responsive organic/inorganic hybrid hydrogels by combining poly(2-(2-methoxyethoxy) ethyl methacrylate-co-oligo (ethylene glycol) methacrylate-co-acrylic acid) (PMOA) hydrogel with magnetic attapulgite/Fe3O4 (AT-Fe3O4) nanoparticles were applied to the removal of Rhodamine B (RhB) dye from wastewater. The adsorption of RhB by the hydrogels was carried out under different external environmental, such as pH, temperature and magnetic-field. The results showed that the hydrogels still possessed temperature, pH and magnetic-field sensitivity during the adsorption process, which indicated that the adsorption could be controlled by the hydrogels responsive. The dye adsorption had a significant increment at 30°C and the removal of RhB could reach to over 95%. Besides, the low pH values were also favorable for the RhB adsorption, the removal was over 90% at pH = 4.56. Kinetic studies showed that the pseudo-second order kinetic model well fitted the experimental data. The rate constant of adsorption was 0.0379 g/mg min. Langmuir and Freundlich isotherm models were applied to the equilibrium adsorption for describing the interaction between sorbent and adsorbate. The maximum KL and KF were 2.23 (L/g) and 0.87 (mg/g) at 30°C, respectively. Under the external magnetic-field, the adsorption rate significantly increased within 250 min and the hydrogels could be separated easily from wastewater. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42244.
Co-reporter:Yang Ti;Ying Lv
Journal of Polymer Research 2014 Volume 21( Issue 5) pp:
Publication Date(Web):2014 May
DOI:10.1007/s10965-014-0462-z
In this paper, Fe-octacarboxyl acid phthalocyanine substituted by polyethylene glycol (FeOCAP-PEG) was synthesized. FeOCAP-PEG had good solubility in solvents such as DMAc, DMSO and so on. FeOCAP-PEG/polyurethane (PU) blends were prepared by solution blending. Good compatibility was found between FeOCAP-PEG and PU matrix. FeOCAP was dispersed in the hard segments of PU, while the side chain of PEG was dispersed in the soft segments of PU. Tensile tests showed that the tensile strength, the elongation at break and tensile energy of the samples were improved with increasing FeOCAP-PEG content. The improved mechanical properties were due to the strong interaction formed between FeOCAP-PEG and hard segments of PU, which was investigated by dynamic mechanical analysis (DMA) and fourier transform infrared (FTIR). The degree of microphase separation of the samples increased with increasing FeOCAP-PEG content. The flexibility, the moisture absorption and the antibacterial properties of the samples were also improved with increasing FeOCAP-PEG content.
Co-reporter:Yonggang Peng, Junling Ji, Xiaoyan Zhao, Huaixin Wan, Dajun Chen
Powder Technology 2013 Volume 233() pp:325-330
Publication Date(Web):January 2013
DOI:10.1016/j.powtec.2012.09.018
Rod-like zinc oxide (ZnO) nanopowder was synthesized from zinc acetate via an ultrasound assisted non-hydrolytic sol–gel process. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV–vis spectroscopy. X-ray diffraction confirmed that the as-prepared nanopowder was excellently crystallized. TEM images displayed the samples consisting of rod-like nanocrystallites of about 30 nm width and 50–70 nm length. A plausible nonhydrolytic alcoholysis route based on the well-known ester-elimination reaction that involved the nucleophilic attack of the hydroxyl group of diethylene glycol on the carbonyl carbon atom of zinc acetate was proposed and confirmed by gas chromatography–mass spectroscopy (GC–MS) analysis. Diethylene glycol not only acted as a solvent, but also acted as a reactant and as a capping agent, limiting particles growth and preventing their agglomeration. Photocatalytic degradation of C.I. Acid Red 249 (AR249) was carried out with synthesized ZnO nanopowder. The blank experiments showed that both UV illumination and the catalyst were necessary for the decomposition of AR249. The influences of various operational parameters such as catalyst dose, dye concentration, pH of the solution on percentage photodegradation of AR249 were investigated. The degradation of AR249 was found to be effective in alkaline media and the kinetic of photodegradation followed pseudo-first-order kinetic model. The rate constant for degradation of AR249 was calculated to be 0.01369 min− 1.Rod-like zinc oxide (ZnO) nanopowder was synthesized from zinc acetate using an ultrasound assisted non-hydrolytic sol–gel process. The nanorods have a diameter of about 30 nm and lengths of 50–70 nm. The prepared nanopowder has exhibited good photocatalytic activity against aqueous C.I. Acid Red 249 solution.Highlights► Rod-like ZnO is synthesized by ultrasound assisted non-hydrolytic sol–gel process. ► This preparation approach is a simple, facile and surfactant-free. ► The synthesized ZnO nanorods have a diameter of about 30 nm and lengths of 50–70 nm. ► The ZnO nanorods show good photocatalytic activity for C.I. Acid Red 249 solution.
Co-reporter:Yang Ti, Dajun Chen
Progress in Organic Coatings 2013 Volume 76(Issue 1) pp:119-124
Publication Date(Web):January 2013
DOI:10.1016/j.porgcoat.2012.08.019
In this paper, Fe-octacarboxyl acid phthalocyanine (Fe-OCAP)/polyurethane (PU) blends were prepared by solution blending. The mechanical and dynamic mechanical properties of the samples were evaluated by tensile tests and dynamic mechanical analysis. The results showed that incorporation of Fe-OCAP significantly improved the tensile strength, elongation at break, and thermal deformation property of PU matrix. The interaction between Fe-OCAP and PU was investigated by infrared analysis. The result indicated that strong hydrogen bond was formed between Fe-OCAP and hard segments of PU and increased with increasing Fe-OCAP content. Quantitive evaluations of the interaction between Fe-OCAP and PU were conducted by analyzing the physical cross-linking density in samples. The results indicated that the physical cross-linking density of the samples was increased with increasing Fe-OCAP content.Highlights► Fe-octacarboxyl acid phthalocyanine/polyurethane blends were prepared. ► Mechanical properties of the samples were improved with the increase of Fe-OCAP. ► Additional hydrogen bond was formed between Fe-OCAP and PU. ► Physical cross-linking density in the samples increased with increasing Fe-OCAP.
Co-reporter:Meng Wang, Yun Liao, Dajun Chen
Polymer Testing 2013 Volume 32(Issue 2) pp:175-178
Publication Date(Web):April 2013
DOI:10.1016/j.polymertesting.2012.10.006
In this paper, we present a new method for determination of the linear thermal expansion coefficient (LTEC) of polymeric materials by infrared thermography. The method is based on the thermo-elastic effect, which is closely related to the LTEC. The advantage of this method is that it is not only suitable for any size and shape of polymeric material, but also for both amorphous and crystalline polymers.
Co-reporter:Qinghui Lin;Yiqing Gu
Journal of Applied Polymer Science 2013 Volume 129( Issue 5) pp:2571-2579
Publication Date(Web):
DOI:10.1002/app.38973
Abstract
A novel nanocomposite catalyst was prepared from immobilization of aluminum oxide hydroxide onto the attapulgite. Characterizations with scanning electron microscopy (SEM) and wide angle X-ray diffraction (XRD) of the as-prepared catalyst revealed that AlO(OH) nanoparticles were distributed on the attapulgite. Thermogravimetric analysis-infrared spectrometry (TGA-IR) of the mixture prepared by mixing of bishydroxy ethylene terephthalate (BHET) and the catalyst indicated that attapulgite-supported aluminum oxide hydroxide catalyst can catalyze BHET polycondensation under the applied conditions. A kinetic model for determining the activation energy has been applied to evaluate the catalyst activity. The catalyst activity was examined through comparative experiments, and the results showed that the new catalyst exhibited higher activity for BHET polycondensation under identical reaction conditions, and the viscosity-average molecular weight of poly(ethylene terephthalate) (PET) product obtained was increased about 2000 g/mol. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Co-reporter:Yang Ti
Journal of Applied Polymer Science 2013 Volume 130( Issue 4) pp:2265-2271
Publication Date(Web):
DOI:10.1002/app.39414
ABSTRACT
Fourier transform infrared (FTIR) thermal analysis was utilized to study the temperature dependence of hydrogen bond in Fe-octacarboxyl acid phthalocyanine (Fe-OCAP)/polyurethane (PU) blends. Two regions in the FTIR spectra were concerned to investigate the difference of the degree of hydrogen bond in the samples: the NH stretching region (3210–3460 cm−1) and carbonyl stretching region (1680–1760 cm−1). It was found that the average strength of hydrogen bond in the modified samples was stronger than that in pure PU. With increasing Fe-OCAP content, the hydrogen bonded NH and carbonyl groups were increased, while with increasing temperature they decreased. The equilibrium between free and hydrogen bonded carbonyl groups was discussed. The dissociation enthalpy for hydrogen bonded carbonyl of the samples was increased with increasing Fe-OCAP content. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2265–2271, 2013
Co-reporter:Meng Wang;Yun Liao
Polymer Bulletin 2013 Volume 70( Issue 1) pp:171-180
Publication Date(Web):2013 January
DOI:10.1007/s00289-012-0795-x
In this study, infrared thermography is used to detect the thermal effects of rubber-like materials during loading–unloading cycles. Two salient features of temperature change have been observed: (1) the temperature has a tiny decrease at first and then becomes to increase during the stretching process, which is in agreement with the thermo-elastic inversion effect. (2) Temperature variation is partly reversible in the first cycle and totally reversible in the following cycles. These phenomena are related to complicated deformation mechanisms. Based on the analysis of elastic thermal effects during deformation process, thermodynamics of rubber elasticity has also been investigated by infrared thermography.
Co-reporter:L. Jin;Z. L. Ding;D. J. Chen
Journal of Materials Science 2013 Volume 48( Issue 14) pp:4883-4891
Publication Date(Web):2013 July
DOI:10.1007/s10853-013-7268-y
A novel zinc phthalocyanine containing eight carboxyl groups was synthesized and utilized as a co-adsorbent with lutein for dye-sensitized solar cells enhance the photoelectric conversion efficiency. The effects of various phthalocyanine/lutein mole ratios on the performances of the fabricated solar cells were investigated. The results showed that zinc octacarboxylic phthalocyanine aggregation decreased with the increasing lutein/phthalocyanine mole ratios and zinc octacarboxylic phthalocyanine fluorescence was strongly quenched due to energy transfer from the phthalocyanine to the excited lutein. The photoelectric conversion efficiency reached its maximum when zinc octacarboxylic phthalocyanine/lutein mole ratio was 4:1. Moreover, the charge-transfer resistances and electron lifetimes at the TiO2/dye/electrolyte interface also showed great dependency on the phthalocyanine/lutein mole ratios by electrochemical impedance spectroscopy. The density-functional theory calculation of zinc phthalocyanine suggests that the electronic cloud density distribution move from the phthalocyanine ring framework toward the anchoring carboxylic group and further to the conduction band of TiO2, which results in efficient electron transfer.
Co-reporter:Ling Jin, Dajun Chen
Electrochimica Acta 2012 Volume 72() pp:40-45
Publication Date(Web):30 June 2012
DOI:10.1016/j.electacta.2012.03.167
Attapulgite nanoparticles were used to improve photovoltaic performance of phthalocyanine-sensitized solar cells. The effects of attapulgite on the devices were investigated in details. Adding of attapulgite into TiO2 electrodes not only reduced the adsorption of zinc octacarboxylic phthalocyanine but also prevented phthalocyanine aggregation effect, which greatly improved photovoltaic performance of the dye-sensitized solar cell. The solar cell with 10 mg attapulgite nanoparticles dispersed in the dye solution exhibited nearly three times larger photoelectric conversion efficiency under simulated AM 1.5 G irradiation (100 mW cm−2) when compared to the pure dye, which was further characterized by the electrochemical impedance spectroscopy (EIS). The EIS studies showed that attapulgite decreased the charge-transfer resistances at the TiO2/dye/electrolyte interface, which can promote electron transport.Graphical abstractHighlights► Dye-sensitized solar cells sensitized by zinc octacarboxylic phthalocyanine. ► Attapulgite nanoparticles have been used to suppress phthalocyanine aggregation. ► Adding attapulgite improves the photovoltaic performance of the dye-sensitized solar cells.
Co-reporter:Yang Wang, Aijuan Dong, Zhicheng Yuan, Dajun Chen
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2012 Volume 415() pp:68-76
Publication Date(Web):5 December 2012
DOI:10.1016/j.colsurfa.2012.10.009
In this paper, we successfully fabricated a new kind of multiple stimulus-responsive organic/inorganic hybrid hydrogels by combining dual stimuli-responsive poly (2-(2-methoxyethoxy) ethyl methacrylate-co-oligo (ethylene glycol) methacrylate-co-acrylic acid) (PMOA) hydrogel with magnetic attapulgite/Fe3O4 (AT–Fe3O4) nanoparticles. First, the magnetic nanoparticle was prepared via co-precipitation technique in aqueous suspension of purified attapulgite. The obtained AT–Fe3O4 nanoparticles were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy and vibrating sample magnetometer. Compared with pure attapulgite, the AT–Fe3O4 exhibited better superparamagnetic properties. Then, the AT–Fe3O4 was introduced into the dual-responsive (temperature and pH) PMOA hydrogel network by in situ polymerization. The morphology, responsive behaviors and tensile properties of the prepared hydrogels were systematically characterized by field emission scanning electron microscopy, vibrating sample magnetometer, swelling/re-swelling behaviors and tensile testing. The results showed that the AT–Fe3O4 nanoparticles were well dispersed in the hydrogel matrix, and the multi-functional AT–Fe3O4/PMOA nanocomposite hydrogels had not only temperature/pH sensitivity and good mechanical properties, but also magnetic functionality. The tunable superparamagnetic behavior of these hydrogels depended on the amount of AT–Fe3O4. In addition, the multi-functional AT–Fe3O4/PMOA nanocomposite hydrogels can continue to swell under an alternating magnetic field after equilibrium swelling in deionized water.Graphical abstractHighlights► A new kind of magnetic nanoparticle was prepared via co-precipitation technique. ► Novel multiple stimulus-responsive hydrogels were prepared by in situ polymerization. ► The mf-NC hydrogels have T/pH/magnetic sensitivity and good mechanical properties. ► The mf-NC hydrogel can continue swelling under an alternating magnetic field.
Co-reporter:Meng Wang, Yun Liao, Dajun Chen
Polymer Testing 2010 Volume 29(Issue 6) pp:674-678
Publication Date(Web):September 2010
DOI:10.1016/j.polymertesting.2010.05.004
A new technology is described in which infrared thermography is used to investigate the necking phenomenon in the fiber drawing process. The change of temperature and diameter during the necking process has been determined accurately online by an infrared camera with 18 μm close-up lens. The infrared thermal images showed that self-heating of the fiber only occurred in the necking region. Depending on the drawing rate, the temperature of the necking region was found to exceed the ambient temperature by 40–65 °C.
Co-reporter:Han Yin, Huifang Chen, Dajun Chen
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2010 Volume 367(1–3) pp:52-59
Publication Date(Web):5 September 2010
DOI:10.1016/j.colsurfa.2010.06.017
The major objective of this work is to understand the effects of temperature and clay content on the rheological properties of poly(acrylonitrile) (PAN)/attapulgite (AT) nanocomposite solution. The rheological properties have been studied in both linear and nonlinear viscoelastic response regions. In the linear regime, the nanocomposites exhibit higher storage modulus (G′) and loss modulus (G″) with increasing clay content and the results showed that the clay effect on the elastic improvement of the matrix is much more significant at high temperature than that at lower one. This may attribute to different polymer–clay interaction and the clay dispersion at different thermal state of the matrix. The similar temperature and clay content effect has also been observed in the nonlinear regime and the results further indicated that the presence of small amount of AT nanorods improved the fluidity of the PAN solutions. Finally, a comparison has been made between the complex and steady viscosities to verify the applicability of the empirical Cox-Merz rule and the phenomenological evaluation for the ratio of the topological structure disparity of the matrix in shear thinning process has also been proposed.
Co-reporter:Han Yin;Huifang Chen
Journal of Materials Science 2010 Volume 45( Issue 9) pp:2372-2380
Publication Date(Web):2010 May
DOI:10.1007/s10853-009-4203-3
The major objective of this work is to understand the effects of attapulgite (AT) on the mechanical properties of polyacrylonitrile (PAN)/AT nanocomposite film. The well dispersed but irregularly distributed AT nanoparticles in the matrix was observed by scanning electron microscopy (SEM) and UV–vis spectra. The mechanical properties were investigated by means of tensile tests and dynamic mechanical analyses (DMA). The results showed that the incorporation of AT significantly improved the tensile strength and modulus of the PAN matrix. The fracture morphologies analysis has further suggested that small amount of AT nanorods may slide and orient along the tensile direction, resulting in homogenous stress transfer, thus increase the toughness of the PAN. However, the nanorods network formed in high AT content sample probably hindered the deformation of the matrix and generated the stress concentration points, leading to the remarkable increase of embrittlement of the samples. Following this concept, the volume of the constrained polymer chains was also calculated with DMA data and showed the good correlation with conclusion drawn in the tensile tests.
Co-reporter:Ying Fang, Dajun Chen
Materials Research Bulletin 2010 45(11) pp: 1728-1731
Publication Date(Web):
DOI:10.1016/j.materresbull.2010.06.062
Co-reporter:Han Yin;Huifang Chen
Polymer Engineering & Science 2010 Volume 50( Issue 2) pp:312-319
Publication Date(Web):
DOI:10.1002/pen.21550
Abstract
In this article, poly(acrylonitrile-co-methylacrylate)/attapulgite (AT) nanocomposites have been prepared by mechanical blending. The hydrogen bonding (H-bonding) behavior between the copolymer and unmodified AT were investigated by Fourier Transform Infrared. The results indicated that the H-bond index (HBI) decreased with increasing AT content. According to the dynamic mechanical analysis, the storage modulus and heat distortion temperature of the nanocomposites gradually increased with increasing AT content while the glass transition temperature reached the maximum when AT content was 1 wt%. X-ray diffraction results demonstrated that the sample with the highest HBI value had the lowest crystallinity, suggesting the H-bond interaction restricted the motion of polymer chains, thus decreased crystallinity of the nanocomposites. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Co-reporter:Zhenjun Chang, Yuan Xu, Xin Zhao, Qinghua Zhang and Dajun Chen
ACS Applied Materials & Interfaces 2009 Volume 1(Issue 12) pp:2804
Publication Date(Web):December 10, 2009
DOI:10.1021/am900553k
Surface modification of azide-decorated polyimide (PI) nanofibers with well-defined alkyne-terminated poly(methyl methacrylate) (PMMA) was accomplished via the combination of atom transfer radical polymerization (ATRP) and “click” chemistry. In this work, PI nanofibers were prepared via electrospun polyamic acid (PAA), followed by thermal imidization. Grafting of PMMA onto PI nanofibers was accomplished in three steps: (1) choloromethylation and azidization of PI nanofibers; (2) preparation of alkyne-terminated PMMA by ATRP of methyl methacrylate in toluene using propargyl 2-bromopropionate as initiator; (3) click coupling between the azidized PI nanofibers and the alkyne-terminated PMMA under the catalysis of Cu(I)Br/N,N,N′,N′′-pentamethyldiethylenetriamine (PMDETA). Gel permeation chromatography (GPC), 1H NMR, and Fourier transform infrared (FT-IR) all confirmed the structure of alkyne-terminated poly(methyl methacrylate). The modified surface was characterized by X-ray photoelectron spectroscopy (XPS) after each modification stage. XPS and scanning electron microscope (SEM) were utilized to confirm PMMA-functionalized PI nanofibers, showing polymer coatings present on the surface of PI nanofibers. PI-g-PMMA nanofibers exhibited a more significant reinforcing effect compared to that with ungrafted PI nanofibers.Keywords: click chemistry; electrospinning; polymer nanofibers; reinforcement
Co-reporter:Han Yin;Di Mo
Journal of Polymer Science Part B: Polymer Physics 2009 Volume 47( Issue 10) pp:945-954
Publication Date(Web):
DOI:10.1002/polb.21701
Abstract
Nanocomposites based on poly(acrylonitrile) (PAN) and attapulgite (AT) had been prepared by solution blending in dimethyl sulfoxide (DMSO). The rheological properties of the nanocomposites solutions were investigated by HAAKE rheometer with plate-cone geometry. The steady and oscillation shear experiments were carried out to investigate the effects of clay exfoliation and orientation as well as polymer-clay interaction. The presence of small amount of AT nanoparticles with large aspect ratio improved the fluidity of these PAN solutions under low shear rate, whereas large amount of AT will reduce its aspect ratio by aggregation and constrain the polymer segment motion in the solutions. The relaxation and disentanglement behaviors of the PAN chains in nanocomposite solutions were also studied by oscillation and thixotropic experiments, from which, it can be concluded that well dispersed and oriented AT nanorods will reduce interaction among macromolecules. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 945–954, 2009
Co-reporter:Limei Wang, Fujun Wang, Dajun Chen
Materials Letters 2008 Volume 62(Issue 14) pp:2153-2156
Publication Date(Web):15 May 2008
DOI:10.1016/j.matlet.2007.11.078
In the present work, the silver/polystyrene nanospheres with more uniform particle size and more complete coverage of silver nano-shell have been prepared. The formation of the silver/polystyrene nanospheres was realized by adopting a “one-pot” route. The styrene monomer was at first emulsified by OP-10 to form micelle. The mercaptoethanol played an important role in the process of forming silver/polystyrene shell-core structure. Polymerization of styrene was initiated by the redox system composed of AgNO3/NaBH4. When Ag+ ion was reduced to Ag, it deposited on the surface of the polystyrene nanoparticle to form uniform metallic nanoshell. The morphology of the silver/polystyrene nanospheres have been characterized by Fourier transform infrared spectrometry, X-ray diffraction, transmission electron microscopy, atomic force microscopy, dynamic light scattering and UV–visible absorption measurements.
Co-reporter:Xue-lian Li ;Da-jun Chen
Journal of Applied Polymer Science 2008 Volume 109( Issue 2) pp:897-902
Publication Date(Web):
DOI:10.1002/app.24913
Abstract
In the present work, a series of aromatic/aliphatic co-polyureas have been synthesized from 4,4-diphenylmethane diisocyanate (MDI), m-phenylene diamine (m-PDA), and 1,6-diaminohexane (HDA) in DMAc by a two-stage solution polymerization route. Characterizations of the polyurea products have been carried out by 1H-nuclear magnetic resonance (NMR) and Fourier transform infrared (FT-IR) spectroscopic techniques. Thermal properties of the polyurea samples have been investigated by differential scanning calorimetry and thermogravimetric analysis. The mechanical properties of the polyurea samples have been measured. The results show that the polyurea samples with the expected structure have been synthesized. The results of DSC analysis show the glass transition temperatures of the co-polyurea samples decrease with the increase of HDA content, and fit the Fox equation well. TGA data of the polyurea samples indicate that thermal stability of the aromatic polyurea is better than that of the co-polyureas. The thermal degradation activation energies of the co-polyureas are ∼60–70 kJ/mol. The results of mechanical measurement show that the initial modulus and tensile strength of the co-polyurea samples decrease with the increase of HDA content. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Co-reporter:Yuanqing Xiang, Dajun Chen
European Polymer Journal 2007 Volume 43(Issue 10) pp:4178-4187
Publication Date(Web):October 2007
DOI:10.1016/j.eurpolymj.2007.08.005
In this paper, series of novel pH-responsive silver (Ag) nanoparticle/poly(2-hydroxyethyl methacrylate (HEMA)–poly(ethylene glycol) methyl ether methacrylate (PEGMA)–methacrylic acid (MAA)) composite hydrogel were successfully prepared by in situ reducing Ag+ ions anchored in the hydrogel by the deprotonized carboxyl acid groups. X-ray diffraction (XRD), UV–vis spectrophotometry, transmission electron microscopy (TEM) and electric conductivity tests were used to characterize the composite system. It was found that the size and morphology of the reduced Ag nanoparticles in the composite hydrogels could be changed by loading the Ag+ ions at various swelling ratios of hydrogel. Moreover, compared to the pure poly(HEMA–PEGMA–MAA) hydrogel, not only did the Ag nanoparticle/poly(HEMA–PEGMA–MAA) composite hydrogels exhibit much higher swelling ratio and faster deswelling rate, but also higher pH switchable electrical properties upon controlling the interparticle distance under pH stimulus. The pH responsive nanocomposite hydrogel reported here might be a potentially smart material in the range of applications including electronics, biosensors and drug-delivery devices.
Co-reporter:Lingli Zou;Xingpin Zhou;Wenbin Li;Xiaqin Wang;Baohua Zhang
Journal of Applied Polymer Science 2007 Volume 106(Issue 3) pp:1670-1676
Publication Date(Web):17 JUL 2007
DOI:10.1002/app.26718
A new and facile approach of surface dyeing was developed for cotton and nylon fabrics coated with a novel porous silk fibroin (SF)/silica (SiO2) nanohybrid. Actually, dyeing of the fabrics occurred in the very thin nanohybrid layers exclusively, while the main body of the fabrics remained intact on the whole. With the assistance of the large surface areas of the porous nanohybrid, dye uptake of the coated cotton fabrics dyed with Acid Red GSF or Disperse Cation Red SD-GRL was enhanced substantially compared with that of the uncoated fabrics as a control. Moreover, dye uptake increased with the SF content in the hybrid, indicating that the SF moiety played a significant role for the surface dyeing process. Color fastness to water of both the dyestuffs was much higher for the coated cotton fabrics compared with that of the uncoated ones. Similar results were obtained for the nanohybrid coated nylon fabrics dyed with Disperse Cation Red SD-GRL as those of the coated cotton fabrics. However, no increase was observed for dye uptake of the coated nylon fabrics dyed with Acid Red GSF owing to saturation of the dyestuff attached on the controlled uncoated nylon fabrics, which concealed the contribution of the nanohybrid layer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Co-reporter:Limei Wang, Dajun Chen
Materials Letters 2007 Volume 61(Issue 10) pp:2113-2116
Publication Date(Web):April 2007
DOI:10.1016/j.matlet.2006.08.022
A new method for the preparation of hollow silver spheres was proposed. In the preparation process the mercapto groups played an important role in the process of forming starch/silver core–shell structure, which provided nucleation sites for the growth of a silver shell. Removal of the starch core is realized by degrading the starch template with α-amylase. The morphology of the starch/silver core–shell nanocomposite and the hollow silver spheres was characterized by TEM and AFM.
Co-reporter:Zhiqin Peng;Qi Liu
Polymer Engineering & Science 2007 Volume 47(Issue 4) pp:460-466
Publication Date(Web):1 MAR 2007
DOI:10.1002/pen.20704
Nanocomposites based on biodegradable poly(ε-caprolactone) (PCL) and attapulgite (AT) were prepared by solution mixing. The nonisothermal crystallization of the pure PCL and PCL/AT nanocomposites at different AT contents and different cooling rates were investigated by differential scanning calorimetry (DSC). There are significant dependence of nonisothermal crystallization behavior and kinetics of PCL/AT nanocomposites on the AT content and cooling rate. The Jeziorny method has been employed to analyze the DSC data. The results show that Jeziorny method could describe this system well. It can be concluded that AT can be used as an effective nucleating agent and has effects on the growth of crystallites in the crystallization process of PCL matrix. POLYM. ENG. SCI., 47:460–466, 2007. © 2007 Society of Plastics Engineers.
Co-reporter:Yuan-Qing Xiang;Yan Zhang;Da-Jun Chen
Polymer International 2006 Volume 55(Issue 12) pp:
Publication Date(Web):11 SEP 2006
DOI:10.1002/pi.2091
Hydrogels based on 2-hydroxyethyl methacrylate (HEMA), methacrylic acid (MAA) and poly(ethylene glycol) methyl ether methacrylate (PEGMA) were prepared by free radical polymerization. The prepared hydrogels were characterized using Fourier transform infrared spectrometry. The states of water in the hydrogels were probed using differential scanning calorimetry and three types of water (free, freezing bound and non-freezing bound) were detected, the contents of which were calculated. Compared with conventional poly(HEMA-co-MAA) hydrogels, the deswelling rate of the poly(HEMA-co-PEGMA-co-MAA) hydrogels is significantly improved, owing to the introduction of PEGMA. The deswelling process can be well described with a first-order kinetics equation. Moreover, the swelling ratio of poly(HEMA-co-PEGMA-co-MAA) hydrogels exhibits a temperature dependence. Based on the analysis of the components of the hydrogels, a brushed core/shell structure is proposed for these, and confirmed by transmission electron microscopy observations. Copyright © 2006 Society of Chemical Industry
Co-reporter:Zhiqin Peng
Journal of Polymer Science Part B: Polymer Physics 2006 Volume 44(Issue 14) pp:1995-2000
Publication Date(Web):5 JUN 2006
DOI:10.1002/polb.20855
Poly(vinyl alcohol) (PVA)/attapulgite (AT) nanocomposite fibers have been prepared by wet spinning. The morphology and mechanical properties of the modified PVA fibers have been characterized with transmission electron microscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), birefringence measurements, and mechanical testing. The PVA/AT nanocomposite fibers show much higher tensile strength, initial modulus, and work to break than pure PVA fibers with the same draw ratio. SEM observations demonstrate that the AT nanorods can align orderly along the fiber axis by stretching and have good adhesion to the fiber matrix. The results of birefringence measurements prove that the modified fibers have higher orientation than pure PVA fibers after stretching. The results of DSC analysis indicate that the crystallinity of the PVA fibers can be increased by the addition of AT. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1995–2000, 2006
Co-reporter:Zhiqin Peng
Journal of Polymer Science Part B: Polymer Physics 2006 Volume 44(Issue 3) pp:534-540
Publication Date(Web):19 DEC 2005
DOI:10.1002/polb.20719
Attapulgite (AT)-reinforced poly(vinyl alcohol) (PVA) nanocomposite films were prepared by solution-casting technique. The nonisothermal crystallization behaviors of PVA bulk and PVA/AT nanocomposites have been investigated by differential scanning calorimetry (DSC). It has been found that the uniformly dispersed AT nanorods in the matrix have great influence on the glass transition temperature and crystallization behavior of PVA matrix. The Jeziorny method has been employed to analyze the DSC data. The results show that Jeziorny method could describe this system very well. Comparing with the PVA bulk, PVA/AT nanocomposites have higher crystallinity Xt, shorter semicrystallization time t1/2, and higher crystallization rate constant Zc. It can be concluded that AT can be used as an effective nucleating agent and has effects on the growth of crystallites in the crystallization process of PVA matrix. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 534–540, 2006
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