Xudong Jia

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Name: 贾叙东

Organization: Nanjing University , China

Department: Department of Chemistry and Biochemistry

Title: NULL(PhD)

TOPICS

Analytical Chemistry

Polymer

POSS

Organic Chemistry

Organic Photochemistry

Chemicals
References

Synthesis of heat-resistant benzoxazine-based polyfluorene and its reversible temperature-sensitive fluorescence

Co-reporter:Weizhi Li, Xiangai Yuan, Jin Huang, Bang'an Peng, Feng Zhou, Jing Ma, Xudong Jia

Polymer 2017 Volume 109() pp:126-136

Publication Date(Web):27 January 2017

DOI:10.1016/j.polymer.2016.12.038

•A main-chain benzoxazine-based polyfluorene (BluePF-BZ) with T-sensitive fluorescent property was first reported.•The mechanism of T-sensitive fluorescent property for BluePF-BZ/E44 + D230 was studied by model simulation.•The BluePF-BZ/E44 + D230 possessed high thermal spectral stability and reversible fluorescent response at high temperature.•This work will enrich species of T-sensitive fluorescent polymer, and extend scope of polyfluorenes for T-sensitive property.A novel benzoxazine-containing temperature T-sensitive fluorescent polyfluorenes (BluePF-BZ) had been prepared. A benzoxazine monomer (BHPF-paa) was firstly synthesized with 9,9-Bis(4-hydroxyphenyl)fluorene, propargylamine and paraformaldehyde through Mannich condensation reaction. The as-prepared BHPF-paa was then incorporated into the preparation of polyfluorenes, and the main-chain BluePF-BZ could finally be obtained. The structures of the obtained monomer and polyfluorenes were characterized by 1H NMR and FTIR. The BluePF-BZ was finally incorporated into epoxy resin (E44 + D230) to fabricate the T-sensitive material. The thermal stability, optical stability, and T-sensitive fluorescent properties of BluePF-BZ/E44 + D230 were investigated. The BluePF-BZ/E44 + D230 system showed high spectral thermal stability and reversible T-sensitive fluorescent response in relative high temperature (>433 K). To the best of our knowledge, this is the first report about the T-sensitive fluorescent property of PF. Its mechanism of T-sensitive fluorescent property was also studied by comparative experiment and molecular simulation.

Photodegradable hydrogels for external manipulation of cellular microenvironments with real-time monitoring

Co-reporter:Hanxu Ji;Kai Xi;Qiuhong Zhang

RSC Advances (2011-Present) 2017 vol. 7(Issue 39) pp:24331-24337

Publication Date(Web):2017/05/03

DOI:10.1039/C7RA02629C

With the rapid progress of tissue engineering and regenerative medicine, the cell-friendly construction of a 3D extracellular matrix in a precisely controlled manner is needed. This biomimicry of the native extracellular matrix replicates major aspects of the native cellular microenvironment. Herein, we design a polyethylene glycol (PEG) based hydrogel combined with caging chemistry, which could achieve light-triggered local control of the hydrogel. The crosslinking density of the hydrogel could be tuned with UV exposure by decomposing the structure of the hydrogel. Meanwhile, by introduction of the releasable Rhodamine 110 molecule, we could conveniently monitor the change of the crosslinking density of the hydrogels via fluorescence. By this approach, adjustable user-defined stiffness patterns with different fluorescence intensity in a range of soft tissue microenvironments have been obtained. This novel hydrogel design could be useful for the manipulation of cell fate in various other contexts.

Light and force dual-responsive waterborne polyurethane in multiple states

Co-reporter:Qiuhong Zhang;Yikai Wang;Chong Xing;Yifeng Cai;Kai Xi

RSC Advances (2011-Present) 2017 vol. 7(Issue 21) pp:12682-12689

Publication Date(Web):2017/02/21

DOI:10.1039/C7RA00156H

Light and force-sensitive waterborne polyurethane in multiple states was firstly synthesized and its responsive behaviors were investigated. Di-hydroxyl spiropyran (SP) was prepared and embedded in waterborne polyurethane (WPU) as a chain extender. The SP-WPU showed photo-sensitive properties in both emulsion state and solid state (bulk polymer). The intensity of absorbance at λmax increased as UV (365 nm) irradiation time increased, and decayed when exposed in visible light or in the dark. The SP-WPU emulsion showed a little slower UV activation rate but a much faster decay rate compared with that of SP-WPU film. The SP-WPU emulsion did not show ultrasonic sensitive properties, however, the SP-WPU in the THF/water mixed dispersion showed increasing ultrasonic sensitive properties as water content increased. Moreover, the absorption at λmax of SP-WPU in the solid state increased as elongation increased, especially in the stress stiffening region. The photo-responsive and mechanical responsive waterborne polyurethane could be used as a multi-responsive probe from the solution to the bulk state. It could also provide an environmentally friendly alternative to extend their application in smart coatings and textiles in industry.

Architecture of Conjugated DonorAcceptor (DA)-Type Polymer Films with Cross-Linked Structures

Co-reporter:Jin Huang;Bangan Peng;Weina Wang;Hanxu Ji;Linling Li;Kai Xi;Wenyong Lai;Xinwen Zhang

Advanced Functional Materials 2016 Volume 26( Issue 10) pp:1646-1655

Publication Date(Web):

DOI:10.1002/adfm.201503379

A series of new donor–acceptor (D–A)-type semiconducting conjugated polymers (SCPs), which can form cross-linked structural and supramolecular assembly films by hydrogen-bonding, is successfully synthesized. The microstructures of supramolecular assembly films are further investigated by X-ray diffraction (XRD), high- resolution transmission electron microscopy (HRTEM), and variable-temperature Fourier transform infrared (FT-IR) absorption spectra. As electronic transmission (ET) materials, the SCPs demonstrate superior properties by means of fabricating electron-only devices with the configuration of ITO/ET (SCPs)/Ca/Al. According to space-charge-limited current (SCLC) measurements, fluorine-containing SCPs exhibit much smaller threshold voltages and much higher electron mobilities than Alq₃. Meanwhile, a significant enhancement for their luminescence properties is verified by the photoluminescence (PL) and electroluminescent (EL) spectra of cross-linked-type SCPs, compared to non-cross-linked-type SCPs. The fabricated polymer light-emitting diodes (PLEDs) with the configuration of ITO/PEDOT:PSS/EML (SCPs)/BCP/LiF/Al are able to emit the color from green to red with moderately low turn-on voltages. These results suggested that cross-linked D–A-type SCP can become a potential candidate as a kind of multifunctional materials applied in the field of optoelectronic devices.

Carbon dot cluster as an efficient “off–on” fluorescent probe to detect Au(III) and glutathione

Co-reporter:Jiangjiang Gu, Donghua Hu, Weina Wang, Qiuhong Zhang, Zhen Meng, Xudong Jia, Kai Xi

Biosensors and Bioelectronics 2015 Volume 68() pp:27-33

Publication Date(Web):15 June 2015

DOI:10.1016/j.bios.2014.12.027

•Au(III) decorated carbon dot cluster (Au(III)/CDC) was synthesized to detect glutathione (GSH) through fluorescence “off–on” approach.•The “off” process was realized by the introduction of Au(III) on luminescent carbon dots (CDs), which formed the Au(III)/CDC and quenched the fluorescence of CDs selectively.•The fluorescence of Au(III)/CDC was recovered selectively by biothiols to achieve the “on” process.•The simple, efficient and low cost “off–on” fluorescent probe was applied to detect GSH in MCF-7 cells with/without the oxygen stress.In this paper, we reported for the first time that Au(III) decorated carbon dot cluster (Au(III)/CDC) was synthesized to detect glutathione through fluorescence “off–on” approach. The “off” process was realized by the introduction of Au(III) on luminescent carbon dots (CDs), which formed the complex of Au(III)/CDC and quenched the fluorescence of CDs efficiently. This “off” process was used to detect Au(III) with the selectivity among 21 metal ions and the limitation was 0.48 μM (S/N=3). Au(III) could be removed from the complex by biothiol in the solution, which restored the fluorescence of CDC to achieve the “on” process. This process was selective for biothiols (especially for glutathione) among saccharides, dopamine and amino acids and the limit of detection was 2.02 μM (S/N=3). Due to the dependence of the fluorescence restoration on the concentration of glutathione, Au(III)/CDC was applied as the fluorescence sensor for detection of glutathione in the solution and cellular cytosol. By referring to the fluorescence change in the solution, the intracellular glutathione with/without oxygen stress was evaluated. As compared with the commercial assay, our Au(III)/CDC based assay was simple, facile and low cost, which would be useful to measure intracellular glutathione at different cellular states.

Greatly enhanced thermo-oxidative stability of polybenzoxazine thermoset by incorporation of m-carborane

Co-reporter:Xin Huang;Qiuhong Zhang;Zheng Meng;Jiangjiang Gu, ;Kai Xi

Journal of Polymer Science Part A: Polymer Chemistry 2015 Volume 53( Issue 8) pp:973-980

Publication Date(Web):

DOI:10.1002/pola.27525

ABSTRACT

Novel polybenzoxazine precursor containing m-carborane unit in the main-chain has been firstly synthesized through click reaction of diazidomethyl m-carborane (DAMC) and diacetylene bisbenzoxazine (DABB). Meanwhlie, the traditional polybenzoxazine precursor was also prepared through click reaction of diazidomethyl p-benzene (DAPB) and DABB as a control. 1H NMR was used to confirm the structures of the monomers and the resulting polymers. FT-IR and differential scanning calorimetry (DSC) were used to study the curing behavior of carborane-containing benzoxazine polymer (CCBP). Dynamic mechanical analysis (DMA) study demonstrated that the cured CCBP had high storage moduli and high Tg. Thermogravimetric analysis (TGA) and ablation test showed that the cured CCBP had outstanding thermo-oxidative stability. During thermal ablation of cured CCBP, organic material was degraded, and a passivation layer with oxidized m-carboranes was formed, which prevented the underlying polymer from further degradation. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 973–980

A novel high efficiency composite catalyst: single crystal triangular Au nanoplates supported by functional reduced graphene oxide

Co-reporter:Weina Wang, Jiangjiang Gu, Wenwen Hua, Xudong Jia and Kai Xi

Chemical Communications 2014 vol. 50(Issue 64) pp:8889-8891

Publication Date(Web):22 May 2014

DOI:10.1039/C4CC03306J

To improve the utilization efficiency of Au catalyst, triangular Au nanoplates on functional reduced graphene oxide were prepared by a facile method. The products with ultra-low trace amounts of Au afforded high catalytic efficiency for the reduction of 4-nitro phenol. The morphology of the products was controlled by tuning the addition of HAuCl4.

Synthesis of stable Au–SiO2 composite nanospheres with good catalytic activity and SERS effect

Co-reporter:Weina Wang, Zhen Meng, Qiuhong Zhang, Xudong Jia, Kai Xi

Journal of Colloid and Interface Science 2014 Volume 418() pp:1-7

Publication Date(Web):15 March 2014

DOI:10.1016/j.jcis.2013.11.043

•Monodisperse Au–SiO2 composite nanospheres were synthesized through a one-pot method.•The morphologies and sizes of the composite nanospheres were both controllable.•The nanospheres displayed different SERS effects by adjusting their morphologies.•The products showed high catalytic activity in catalytic reduction of 4-nitrophenol.For improving stability and efficiency of noble metal nanomaterials, a straightforward one-step method was developed to synthesize Au–SiO2 composite nanospheres. Monodisperse hybrid silica nanospheres that had anilino-methyl on the surfaces were prepared first. The as-prepared hybrid silica nanospheres were then used to obtain Au nanocrystal through the redox reaction of HAuCl4 and anilino-methyl. This approach led to a better utilization of Au. By adjusting the surface morphologies and the particle sizes, the functional nanospheres displayed different surface-enhanced Raman scattering effects of Rhodamine 6G. The composite nanospheres showed high catalytic activity and good reusability in catalytic reduction of 4-nitrophenol because of their active gold surface.

New bead type and high symmetrical diallyl-POSS based emissive conjugated polyfluorene

Co-reporter:Jin Huang, Weina Wang, Jiangjiang Gu, Weizhi Li, Qiuhong Zhang, Yin Ding, Kai Xi, Youxuan Zheng, Xudong Jia

Polymer 2014 Volume 55(Issue 26) pp:6696-6707

Publication Date(Web):15 December 2014

DOI:10.1016/j.polymer.2014.10.071

A new bead type and diallyl-POSS based polyfluorene (P2) with high symmetrical structure was synthesized via Heck coupling reaction between oligomeric alkynyl fluorene (P1) and diallyl polyhedral oligomeric silsesquioxanes (diallyl-POSS). The molecular weight and the conjugated length of P1 and P2 were well controlled to acquire good solubility and excellent optical property. The bead-type POSS based polymer was characterized by gel permeation chromatography (GPC), FT-IR, 1H NMR and photoluminescence (PL) spectra. High Resolution Transmission Electron Microscopy (HRTEM) micrographs showed that diallyl-POSS were uniformly nano-dispersed in the polymer matrix. Compared with P1, the POSS based polyfluorene P2 exhibited not only a higher thermal stability, but also an improved photophysical property in solution and solid states. The incorporation of diallyl-POSS resulted effectively in inhibiting the strong stacking/dipole–dipole interaction between fluorescent groups in the polyfluorene. The experimental results indicate that the bi-functional POSS based light-emitting polymers with high symmetrical structure can have great potential in optical materials and devices, such as OPV or PLED, etc.

Rheological study of the gelation of cross-linking polyhedral oligomeric silsesquioxanes (POSS)/PU composites

Co-reporter:Qiuhong Zhang, Xin Huang, Xiaoliang Wang, Xudong Jia, Kai Xi

Polymer 2014 Volume 55(Issue 5) pp:1282-1291

Publication Date(Web):10 March 2014

DOI:10.1016/j.polymer.2014.01.040

The gelation process of N-Phenylaminomethyl-POSS/PU (polyurethane) nanocomposites during curing and at the stable state after curing was investigated by rheology. An increase in dynamic shear moduli, G′ and G″, was observed during the dynamic temperature ramps of the sample. In time-resolved mechanical spectroscopy (TRMS), G′ and G″ increased with curing time at constant curing temperatures over a wide of frequencies. The gelation time of the composites decreased with the rise of curing temperature or with the increase of POSS concentration. The relaxation exponent n at the critical gel was around 0.73. The gel stiffness S decreased as curing temperature increased or as POSS concentration increased. After the completion of the curing reaction, the critical concentration of POSS beyond which the gelation of POSS/PU composites would happen was found around 2.5 wt%. The viscoelastic properties of crosslinking POSS/PU fitted time–temperature-superposition well which implied the incorporation of multifunctional POSS into PU increased the homogeneity of crosslinking POSS/PU composites. Surprisingly, the modulus of the fully cured materials between 2.7 wt% and 6 wt% could also be supposed onto a master curve at high temperature, which implied self-similarity of network near the critical gel. The similar microstructure of POSS/PU at stable state was also confirmed by TEM. The network formation mechanism and the fine structure of the crosslinking POSS/PU were firstly investigated which would provide technical and theoretical basis for other hybrid crosslinking systems.

Greatly enhanced mechanical properties and heat distortion resistance of poly(L-lactic acid) upon compositing with functionalized reduced graphene oxide

Co-reporter:Pengpeng Chen, Yuan Wang, Teng Wei, Zhen Meng, Xudong Jia and Kai Xi

Journal of Materials Chemistry A 2013 vol. 1(Issue 32) pp:9028-9032

Publication Date(Web):05 Jul 2013

DOI:10.1039/C3TA12060K

Poly(L-lactic acid) (PLLA) is a potential candidate for a new renewable resource, but often suffers from a sharp decrease in the storage modulus and heat distortion resistance when the temperature is higher than 60 °C. In this work, reduced graphene oxide (RGO) was introduced to composite with PLLA, which greatly improved the mechanical properties and heat distortion resistance of PLLA. To assist the blending, RGO was firstly chemically functionalized with N-(aminoethyl)-aminopropyltrimethoxysilane (KH792), to improve its compatibility with PLLA. The storage modulus of the PLLA was enhanced by 1500% (from 20 to 300 MPa) around the glass transition temperature, when only 0.5 wt% KH792–RGO was incorporated. Meanwhile, the heat distortion resistance of the PLLA–KH792–RGO was also greatly improved. An investigation on the rheological behavior of the nanocomposite indicated that a network of RGO had been formed in the nanocomposite, which provided an efficient interface interaction with the PLLA. The enhanced stiffness of the PLLA, by introduction of a functionalized RGO network, was preserved well in the rubber state.

Hybrid networks based on poly(styrene-co-maleic anhydride) and N-phenylaminomethyl POSS

Co-reporter:Pengpeng Chen, Xin Huang, Qiuhong Zhang, Kai Xi, Xudong Jia

Polymer 2013 Volume 54(Issue 3) pp:1091-1097

Publication Date(Web):5 February 2013

DOI:10.1016/j.polymer.2012.12.047

Novel PSMA-POSS nanocomposites were prepared, in which N-phenylaminomethyl polyhedral oligomeric silsesquioxane (POSS) was conducted as crosslink agent to incorporate to poly(styrene-co-maleic anhydride) (PSMA). POSS was introduced by one-step reactive solution blend in amounts of 1–30 wt%. FTIR measurement evidenced the occurrence of amidation reaction between the anhydride group of PSMA and the secondary amino group of POSS. This reaction turned out to promote POSS well dispersed in the polymer matrix, and the PSMA-POSS hybrids showed no macro phase separation even if POSS concentration was up to 30 wt%. DSC results showed that the glass transition temperature (Tg) increased to 168 °C with the increase of POSS loading. Dynamic mechanical thermal analysis (DMTA) revealed the storage modulus at high temperature increased with the addition of POSS due to the formation of a permanent network. Incorporation of POSS also improved the thermal properties of PSMA-POSS composites.

A novel thermal-resistant copolymer from polysiloxane-based polybenzoxazine precursor and ferrocene-based benzoxazine monomer

Co-reporter:Weizhi Li, Jun Chu, Liang Heng, Teng Wei, Jiangjiang Gu, Kai Xi, Xudong Jia

Polymer 2013 Volume 54(Issue 18) pp:4909-4922

Publication Date(Web):16 August 2013

DOI:10.1016/j.polymer.2013.06.056

A novel copolybenzoxazine was prepared from polybenzoxazine precursor containing polysiloxane (PBA-pdms 600) and ferrocene-based benzoxazine monomer (BA-fcma). The structures of the precursor and monomer were confirmed by IR and 1H NMR. DSC results suggest that the ring-opening temperature of the copolymers can be decreased by introduction of BA-fcma. SEM illustrates that the domain of the self-crosslinked polyBA-fcma is dispersed into the copolymer networks from nano to micro scale with the increase of BA-fcma. TGA shows that the thermal stability of the copolymers is significantly improved compared with that of homopolymers either in nitrogen or air atmosphere. DMA results exhibit that storage modulus (E′) of the copolymers is greatly enhanced. The three peaks in tanδ curve illustrate that there are three crosslinking structures in the copolymers. The structure and the degradation mechanism of the copolymers are investigated by Pyrolysis/GC–MS technique.

Preparation of novel benzoxazine monomers containing ferrocene moiety and properties of polybenzoxazines

Co-reporter:Weizhi Li, Teng Wei, Yinchun Gao, Kai Xi, Xudong Jia

Polymer 2012 Volume 53(Issue 6) pp:1236-1244

Publication Date(Web):9 March 2012

DOI:10.1016/j.polymer.2012.01.052

Novel benzoxazine monomers containing ferrocene were prepared, one monomer was monofunctional benzoxazine ferrocenylmethyl-3,4-dihydro-2H-1,3-benzoxazine (pC-fcma), and the other was bifunctional benzoxazine, bis(ferrocenylmethyl-3,4-dihydro-2H-1,3-benzoxazinyl)isoprapane (BA-fcma). Followed by thermal cure of monomers, metallopolybenzoxazines with ferrocene moiety in the polymer networks were obtained. The chemical structures of the novel monomers were confirmed by IR, 1H NMR and elemental analysis. The cure behaviors of the monomers, pC-fcma and BA-fcma were studied by DSC. The thermograms of BA-fcma showed multiple peaks, which were resulted from the quickly forming network and the bulkiness factor of ferrocene moiety. In addition, the first peak temperature was much decreased by nearly 70°°C than that of typical B-a benzoxazine, which was mainly due to the electron-donating effect of N-ferrocen group stability of zwitterionic intermediates. TGA suggested that thermal stability of metallopolybenzoxazines was improved, in particular, the weight loss temperature of 5% for polyBA-fcma was increased by almost 100 °C than that of PB-a, and the char yield even reached 60% at 800 °C under N2. Cyclic voltammetry studies of pC-fcma and BA-fcma showed that the species underwent one reversible and one-electron redox coupling.

Synthesis of dissymmetrical nanoparticles with a new hybrid silica template

Co-reporter:Zhen Meng, Chunyan Xue, Luyao Lu, Bo Yuan, Xuehai Yu, Kai Xi, Xudong Jia

Journal of Colloid and Interface Science 2011 Volume 356(Issue 2) pp:429-433

Publication Date(Web):15 April 2011

DOI:10.1016/j.jcis.2011.01.050

An easy, novel route to prepare Janus nanoparticles and nano-bowls with tunable shapes has been developed. This approach uses a new kind of monodisperse vinyl-silica nanoparticles as templates to obtain large amounts of uniform Janus particles and nano-bowls (several grams). The efficient method adopts water-based hydrolysis-condensation and seed-emulsion polymerization. The uniform Janus nanoparticles and nano-bowls will display wide potential applications in many fields, such as: chemical sensors, construction of complex superstructures and nano-bioreactors.Graphical abstractAn effective method has been developed using a new type of template for obtaining large amounts of uniform Janus particles and nano-bowls (several grams) with tunable shapes through seed-emulsion polymerization.Research highlights► A new type of template to synthesis eccentrical core–shell nanoparticles. ► Synthesis of uniform Janus nanoparticles with tunable shapes in large amounts. ► Different shapes of nanoparticles (from mushroom-like to bowl-like) can be obtained by hydrofluoric acid etch. ►The bowl-like nanoparticles’ inner and outer surfaces have distinct properties.

A novel biosensor based on a gold nanoflowers/hemoglobin/carbon nanotubes modified electrode

Co-reporter:Ying-Chun Gao, Kai Xi, Wei-Na Wang, Xu-Dong Jia and Jun-Jie Zhu

Analytical Methods 2011 vol. 3(Issue 10) pp:2387-2391

Publication Date(Web):15 Sep 2011

DOI:10.1039/C1AY05378G

Well-oriented 3D gold flower-like nanoparticles were successfully synthesized by a facile one-pot method, and the gold nanoflowers (AuNFs) were mixed with hemoglobin (Hb) to form a gold nanoflowers/hemoglobin composite. The composite was further combined with multiwalled carbon nanotubes on a glassy carbon electrode (GCE) to fabricate a novel biosensor. The sensor has high stability and bioactivity, and was studied by scanning electron microscopy (SEM) and cyclic voltammetry (CV). The hemoglobin/gold nanoflowers/multiwalled carbon nanotubes glassy carbon electrode (Hb/AuNFs/CNTs/GCE) either retained the Hb in similar native conformations or promoted direct electron transfer. Moreover, the sensor exhibited remarkable catalytic activity toward H2O2 and trichloroacetic acid (TCA). The linear relationship for the determination is in the range of 1.0–60 μM for H2O2 and 0.06–28 mM for TCA. The detection limits were 0.08 μM and 7.3 μM (S/N = 3), respectively.

Synthesis of N-Phenylaminomethyl POSS and Its Utilization in Polyurethane

Co-reporter:Qiuhong Zhang, Hui He, Kai Xi, Xin Huang, Xuehai Yu, and Xudong Jia

Macromolecules 2011 Volume 44(Issue 3) pp:550-557

Publication Date(Web):January 10, 2011

DOI:10.1021/ma101825j

A new functional N-phenylaminomethyl POSS was synthesized by traditionally controlled hydrolytic condensation in one step reaction. The POSS structure was ascribed to a T10 and T12 derivative mixture as main component by varied characterization methods such as 1H NMR, 13C NMR, 29Si NMR, gel permeation chromatography (GPC) and matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI−TOF MS). Then based on this new POSS reacted with polyether diisocyanate, a series of POSS−PU composites with different POSS concentration was prepared and characterized. The POSS−PU composites showed no macrophase separation up to 52 wt % POSS concentration. The high resolution transmission electron microscopy (HRTEM) images of POSS−PU composites showed a well separated nanostructure of POSS with a typical phase size of 5−10 nm. A critical POSS concentration of 26 wt % was found by DMA, beyond which the POSS−PU showed a permanent network at high temperature. Tg and storage modulus of POSS−PU composites increased with increasing POSS concentration. Young’s modulus largely enhanced with increasing POSS concentration at constant Ttest − Tg. All the enhanced mechanical properties could be ascribed to the synergetic effect of POSS and PU, where POSS played a role as the nanoscale cross-linker in the PU system and formed a network, thus hindering the motion of the PU chain.

Synthesis and biocompatibility of anionic polyurethane nanoparticles coated with adsorbed chitosan

Co-reporter:Dan Xu, Ke Wu, Qiuhong Zhang, Heyi Hu, Kai Xi, Qingming Chen, Xuehai Yu, Jiangning Chen, Xudong Jia

Polymer 2010 Volume 51(Issue 9) pp:1926-1933

Publication Date(Web):20 April 2010

DOI:10.1016/j.polymer.2010.03.008

Through the assembly of polyelectrolyte in aqueous emulsion, we synthesized a series of core–shell ionic complex nanoparticles containing anionic polyurethane (PU) and cationic chitosan (CS). The physicochemical properties of PU–CS ionic complex (PU-c-CS) materials were investigated by IR, XPS, DLS, TEM, AFM, general tensile tests, and surface contact angle measurement. It was found that the sizes of the prepared nanoparticles were in the range from 60 to 220 nm, and the films exhibited good mechanical properties. The cell (HUVECs) culture experiments showed that the PU-c-CS films exhibited very low cytotoxicity and supported cell adhesion and growth. Protein (BSA) adsorption was significantly decreased for the PU-c-CS films. Furthermore, the results of prothrombin time (PT) and activated partial thromboplastin time (APTT) indicated that antithrombogenicity of the materials were effectively improved.

Ultra low dielectric constant polysilsesquioxane films using T8(Me4NO)8 as porogen

Co-reporter:Kai Xi, Hui He, Dan Xu, Renjie Ge, Zhen Meng, Xudong Jia, Xuehai Yu

Thin Solid Films 2010 Volume 518(Issue 17) pp:4768-4772

Publication Date(Web):30 June 2010

DOI:10.1016/j.tsf.2010.01.020

A class of ultra low dielectric constant polymethylsilsesquioxane (PMSQ) films with T8(Me4NO)8 polyhedral oligomeric silsesquioxanes (T8 POSS) as double-effective porogen was studied. Through the Me4NO− groups of T8 POSS attacking the Si–O–Si chains of PMSQ, the POSS will be connected to the PMSQ crosslink system. POSS has the cage structure, which acted as the closed pores (≤ 1.5 nm). On the other hand, the Me4NO− groups served as the sacrificial template. When they decomposed after annealing, the open pores were then left in the films. The introduction of T8 POSS can greatly decrease the dielectric constant of PMSQ, and effectively improve its mechanical strength owing to T8(Me4NO)8 interconnected with PMSQ. These continuous and smooth films were prepared by spin-coating with thickness in the range of 60–200 nm. The dielectric constant of the films could be controlled by adjusting the proportion of porogen. These films showed good mechanical strength and ultra low dielectric constant. In particular, a POSS/PMSQ film with ultra low dielectric constant of 1.6 and modulus of 7 GPa had been prepared on silicon wafer by spin-coating.

Preparation of Highly Monodisperse Hybrid Silica Nanospheres Using a One-Step Emulsion Reaction in Aqueous Solution

Co-reporter:Zhen Meng, Chunyan Xue, Qiuhong Zhang, Xuehai Yu, Kai Xi and Xudong Jia

Langmuir 2009 Volume 25(Issue 14) pp:7879-7883

Publication Date(Web):April 9, 2009

DOI:10.1021/la900458b

Highly monodisperse hybrid spherical silica nanoparticles with diameters ranging from 30 to 200 nm were prepared by a one-step emulsion polymerization in aqueous solution. In contrast with the former method for preparing the hybrid silica materials, our method has three advantages. (1) Through this one-pot route, hybrid silica particles with organic functional groups on the surface are prepared in aqueous solution. (2) The particles are created in a size range of 30−200 nm and highly monodisperse. (3) The size of the particles can be effectively well-defined and precisely controlled depending upon the synthesis conditions such as the concentration of surfactant. Other kinds of organosilane monomers have also been tried in the same way. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS) were performed to elucidate the morphologies of the hybrid silica particles. Thermogravimetric analysis (TGA), 29Si NMR, and 13C NMR were used to gain information about thermal properties and detail structure. This approach may open a new broad avenue for the hybrid material in the field of photocrystal, electronic enveloping.

A novel biosensor based on a gold nanoflowers/hemoglobin/carbon nanotubes modified electrode

Co-reporter:Ying-Chun Gao, Kai Xi, Wei-Na Wang, Xu-Dong Jia and Jun-Jie Zhu

Analytical Methods (2009-Present) 2011 - vol. 3(Issue 10) pp:NaN2391-2391

Publication Date(Web):2011/09/15