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Kuo C.-P.,Roosevelt Road | Chuang C.-N.,Institute of Polymer Science and Engineering | Chang C.-L.,Roosevelt Road | Leung M.-K.,Roosevelt Road | And 3 more authors.
Journal of Materials Chemistry C | Year: 2013

We report the study of the fluorescence switching properties of the conjugated copolymers containing triphenylamine, fluorene, benzo[2,1,3] thiadiazole, and cyclic urea moieties. The copolymers show excellent thermal stability and good solubility in polar organic solvents. While the electrofluorescent device (EFD) of P1 emits yellow light under UV excitation, fluorescence intensity is switched off upon electrochemical oxidation. In addition, the fluorescent behavior of the EFD of P1 can be reversibly switched between the non-fluorescent (oxidized) state and the fluorescent (neutral) state with a superb contrast ratio (If/If0) of 21.4. Furthermore, a white-light electrochemical fluorescence switching device is achieved by blending of P1 (yellow) with P2 (blue). Since the fluorescent conjugated polymers of P1 and P2 have their emission simultaneously quenched under the low working potential, the EFD could show a white-dark state of fluorescence with a high contrast ratio (If/If0) of 14.6. © 2013 The Royal Society of Chemistry.


Jian J.,Tsinghua University | Li Z.-J.,Tsinghua University | Ye H.-M.,Institute of Polymer Science and Engineering | Yuan M.-Q.,Institute of Forensic science | Chen G.-Q.,Tsinghua University
Bioresource Technology | Year: 2010

Polyhydroxyalkanoate synthase gene phaCah in Aeromonas hydrophila strain 4AK4 was deleted and its function was replaced by phaC1ps cloned from Pseudomonas stutzeri strain 1317 which favors 3-hydroxyhexanoate (3HHx) and longer chain length monomers. Genes fadD and fadL encoding Escherichia coli acyl-CoA synthase and Pseudomonas putida KT2442 fatty acid transport protein, respectively, were introduced into the recombinant with new phaC1ps. Accumulation of a series of novel medium-chain-length polyhydroxyalkanoates (mcl-PHA) consisting of 80-94 mol% 3HHx were observed. The recombinant accumulated 54% poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) in cell dry weight consisting of 94.5 mol% 3HHx or 51% poly(3-hydroxybutyrate-co-3-hydroxyhexanoate-co-3-hydroxyoctanoate) consisting of 82 mol% 3HHx and 16 mol% of 3HO during a two-step cultivation process under nitrogen limitation when grown on sodium hexanoate or sodium octanoate. The two polyesters containing high percentage of 3HHx are physically characterized. They could be used as biodegradable pressure sensitive adhesives, coatings, polymer binding agents in organic-solvent-free paints or a source for chiral R-3-hydroxyhexanoate. © 2010 Elsevier Ltd. All rights reserved.


Lee Y.-H.,Institute of Polymer Science and Engineering | Chang C.-J.,Institute of Polymer Science and Engineering | Kao C.-J.,Institute of Polymer Science and Engineering | Dai C.-A.,National TaiwanUniversity
Langmuir | Year: 2010

In this study, we synthesized organic/inorganic hybrid materials containing cadmium sulfide (CdS) nanoparticles using a novel amphiphilic conducting block copolymer as a synergistic structure-directing template and an efficient exciton quencher of the hybrid. The amphiphilic rod-coil block copolymer of polyphenylene-b-poly(2-vinyl pyridine) (PPH-PVP) was first prepared from its coil-coil precursor block copolymer of poly(1,3-cyclohexadiene)-b-poly(2-vinyl pyridine) (PCHD-PVP) by using sequential anionic polymerization followed by the aromatization reaction of converting the PCHD block to form conducting PPH. The synthesized PCHD-PVP block copolymers self-assembled into different bulk nanostructures of lamellae, cylinders, and spheres at a volume fraction similar to that of many coil-coil block copolymer systems. However, an enhanced chain-stiffness-induced morphological transformation was observed after the aromatization reaction. This is evidenced by the TEM observation in which both spherical and cylindrical structured PCHD-PVPs transform into lamellar structured PPH-PVPs after aromatization. In addition to the bulk-phase transformation, the rigid-rod characteristic of the conducting PPH block also affects the self-assembling property of the block copolymers in their solution state. CdS nanoparticles were synthesized in situ in a selective solvent of THF using PCHD-PVP and PPH-PVP micelles as nanoreactors. The PPH-PVP/Cd ion in THF exhibits a new ringlike structure of uniform size (̃50 nm) with PPH in the inner rim and complexed PVP/Cd ions in the outer rim as a result of the effects of strong intermolecular forces between PPH segments and the solvophobic interaction. CdS nanoclusters were subsequently synthesized in situ from the PPH-PVP/Cd2+ ring structure, forming a nanohybrid with intimate contact between the PPH domain and CdS nanoparticles. In particular, we found that there is an efficient energy/electron transfer between the conducting PPH domain and CdS nanoparticles in the hybrid, resulting in an enhanced PL quenching effect. The novel nanohybrid shows the potential to be used for optoelectronic applications. © 2010 American Chemical Society.


Yang C.,Institute of Polymer Science and Engineering | Liu P.,Institute of Polymer Science and Engineering
Synthetic Metals | Year: 2010

Polypyrrole/conductive mica (PPy/CM) composites were prepared by coating polypyrrole (PPy) onto the surfaces of the conductive mica (CM) via the in situ chemical oxidative polymerization method. The encapsulating morphologies were revealed with the scanning electron microscopy (SEM) technique. The PPy/CM composites were characterized with Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The composites possess high electrical conductivity at room temperature, the weak temperature dependence of the conductivity. Based on the cyclic voltammetry and the charge/discharge behavior of the PPy/CM composites, it was found that the composites performed typical electrochemical supercapacitor behavior. © 2010 Elsevier B.V. All rights reserved.


Liu P.,Institute of Polymer Science and Engineering | Mu B.,Institute of Polymer Science and Engineering | Du P.,Institute of Polymer Science and Engineering | Hong Z.,Institute of Polymer Science and Engineering
IET Nanobiotechnology | Year: 2013

The crosslinked polystyrene nanocapsules with controllable crosslinking degree have been prepared by the ultraviolet (UV)-induced photocrosslinking of the polystyrene grafted silica nanoparticles (SN-PS), which was obtained by the surface-initiated atom transfer radical polymerisation of styrene from the modified silica nanoparticle templates, after the silica templates were etched with hydrofluoric acid. The effect of the UV-irradiating time on the inner diameter of the nanocapsules, and the degree of crosslinking and the thickness of the shells was investigated. The dynamic light scattering results showed that the degree of crosslinking of the obtained nanocapsules increased with the prolongation of the UV-irradiation time, therefore the inner diameter of the nanocapsules increased. However, the percentage of grafting of the crosslinked polymer shells decreased with increasing the UV-irradiation time because of the photodecomposition of the polystyrene grafted during the UV-irradiated crosslinking process, according to the thermogravimetric analysis. © The Institution of Engineering and Technology 2013.


Liu G.,Institute of Polymer Science and Engineering | Liu P.,Institute of Polymer Science and Engineering
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2010

The preparation conditions of the monodispersed crosslinked polystyrene nanoparticles decorated with surface carboxyl groups via soapless emulsion polymerization with oleic acid (OA) as emulsifying comonomer (surfmer) and divinyl benzene (DVB) as crosslinker were optimized in the present work. The effects of the amounts of surfmer, crosslinker and initiator added, polymerization time on the particle sizes of the nanoparticles were investigated by the dynamic laser light scattering (DLS) analysis. Monodispersed functional crosslinked polystyrene nanoparticles with the particle size near 250 nm were obtained for the optimum polymerization condition. © 2009 Elsevier B.V. All rights reserved.


Zhang L.,Institute of Polymer Science and Engineering | Liu P.,Institute of Polymer Science and Engineering
Materials Letters | Year: 2010

γ-Fe 2O 3 nanoparticles were used as the reactive templates for the fabrication of the hollow polyaniline nanoparticles via the chemical oxidative polymerization of aniline in the presence of hydrochloric acid. The particle size of the doped hollow polyaniline nanoparticles in the emeraldine form was determined by the reactive template. It was found that the reacting temperature played an important role in the formation of the hollow nanoparticles because of the low redox potential of Fe(III) ion. However, the kind of the protonic acids used had no influence on the fabrication of the hollow nanostructure. The formation mechanism of the hollow polyaniline nanoparticles was also proposed. © 2011 Elsevier Ltd. All rights reserved.


Lin C.-Y.,Institute of Polymer Science and Engineering | Hsu S.-h.,National Taiwan UniversityTaipei Taiwan
Journal of Biomedical Materials Research - Part B Applied Biomaterials | Year: 2014

Two different compositions of water-based biodegradable polyurethane (PU) in the form of homogeneous nanoparticles (NPs) were synthesized using biodegradable polyesters as the soft segment. The first PU (PU01) was based on poly(ε-caprolactone) (PCL) diol and the second PU (PU02) was based on 40% PCL diol and 60% polyethylene butylene adipate diol. The PU NP dispersions with different solid contents were sprayed into liquid nitrogen and resuspended in water to generate elastic microspheres (50-60 μm) with different nanoporosities. In vitro degradation analysis revealed that microspheres of PU02 (i.e., PU02 MS) degraded faster than those of PU01 (PU01 MS). Methylene blue was encapsulated during microsphere formation and the release was investigated. Microspheres made from a lower content (10%) of PU02 dispersion (i.e., PU02 MS_10) showed a greater burst release of methylene blue in 6 h, whereas those made from a higher content (30%) of PU01 dispersion (i.e., PU01 MS_30) revealed a prolonged release with a significantly lower burst release. Biocompatibility evaluation using L929 fibroblasts demonstrated that cells were attached and proliferated on microspheres after 24 h. On the other hand, microspheres may further self-assemble into films and scaffolds. Surface modification of microspheres by chitosan may modify the self-assembly behavior of microspheres. Microspheres could be stacked to form scaffolds with different macroporosities. Fibroblasts were successfully seeded and grown in the microsphere-stacked scaffolds. We concluded that the biodegradable and elastic microspheres may be facilely produced from a green and sustainable process with potential applications in drug release and three-dimensional cell culture. © 2014 Wiley Periodicals, Inc.


Yang C.,Institute of Polymer Science and Engineering | Liu P.,Institute of Polymer Science and Engineering | Guo J.,Institute of Polymer Science and Engineering | Wang Y.,Northwest Normal University
Synthetic Metals | Year: 2010

Conductive polypyrrole (PPy) was chemically grafted from the self-assembled monolayer (SAM) coated on expanded vermiculite (VMT), resulting in PPy/VMT nanocomposites after VMT particles were surface modified. X-ray diffraction (XRD) analysis confirmed that the main peaks of PPy/VMT nanocomposites are similar to the SAM-VMT particles, which reveal that the crystal structure of SAM-VMT is well maintained after the coating process under polymerization conditions and exhibit semi-crystalline behavior. Thermogravimetric analysis shows that the thermal stability of PPy/VMT nanocomposites was enhanced and these can be attributed to the retardation effect of amine-functionalized VMT as barriers for the degradation of PPy. The morphology of PPy/VMT nanocomposites showed the sheet structure and encapsulated morphology. The composites possess high electrical conductivity at room temperature, weakly temperature dependence of the conductivity. © 2009 Elsevier B.V. All rights reserved.


Yang C.,Institute of Polymer Science and Engineering | Liu P.,Institute of Polymer Science and Engineering
Synthetic Metals | Year: 2010

The castor oil sulfate (COS), produced by the sulfonation of the castor oil (one of the most promising renewable sources), was used as both the surfactant and the dopant in the chemical oxidative polymerization of pyrrole. The resulting castor oil sulfate doped polypyrrole nanospheres (PPy/COS) were characterized with FTIR, UV-vis, TGA, zeta potentials and TEM techniques. It was found that their diameter decreased and their dispersing stabilities in water increased with the increasing of feeding ratio of COS. The PPy/COS nanospheres possess high electrical conductivity at room temperature and the weak temperature dependence of the conductivity. © 2009 Elsevier B.V. All rights reserved.

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