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Covalently stabilized temperature and pH responsive four-layer nanoparticles fabricated from surface 'clickable' shell cross-linked micelles

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Soft Matter 2009年第7期5卷 1530-1538页

作者： Jiang, Xiaoze Zhang, Guoying Narain, Ravin Liu, Shiyong Department of Polymer Science and Engineering Hefei National Laboratory for Physical Sciences at the Microscale University of Science and Technology of China Hefei Anhui 230026 China Department of Chemistry and Biochemistry Biomolecular Sciences Program Laurentian University 935 Ramsey Lake Rd Sudbury ON P3E 2C6 Canada

Alkynyl-terminated double hydrophilic ABC triblock copolymer, poly(oligo(ethylene glycol) monomethyl ether methacrylate)-b-poly(2- (dimethylamino) ethyl methacrylate)-b-poly(2-(diethylamino) ethyl methacrylate) (alkynyl-POEGMA-b-PDMA-b-PDEA), was synthesized via atom transfer radical polymerization (ATRP) by sequential monomer addition using propargyl 2-bromoisobutyrate (PgBiB) as the initiator. The obtained triblock copolymer dissolves molecularly in acidic media and self-assembles into alkynyl surface-functionalized three-layer "onion-like" micelles consisting of a PDEA core, a PDMA inner shell, and a POEGMA corona at alkaline pH. Selective cross-linking of the PDMA inner shell with 2-bis(2-iodoethoxy)ethane (BIEE) results in structurally stable and surface 'clickable' shell cross-linked (SCL) micelles with pH-responsive PDEA cores. This new kind of SCL micelles could be further surface functionalized or conjugated with other azido- terminated polymer chains, functional groups, or biomolecules via Click chemistry. Four layer nanoparticles (SCL-PNIPAM) which have pH-responsive PDEA cores and temperature responsive PNIPAM outer coronas were fabricated from surface 'clickable' shell cross-linked (SCL) micelles and azide-terminated poly(N-isopropylacrylamide) (PNIPAM-N3) using Click chemistry. These novel four layer nanoparticles might act as suitable nano-sized drug delivery vehicles for the encapsulation and release of hydrophobic drugs as a function of either temperature or pH of the environment. © The Royal Society of Chemistry 2009.

关键词： Nanoparticles

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Effect of poly(γ-glutamic acid) on the gelation of Pluronic F127

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polymers for Advanced Technologies 2009年第8期20卷 703-705页

作者： Lee, Yen-Hsien Yang, Ming-Chien Program of Biomedical Engineering National Taiwan University of Science and Technology Taipei 106 Taiwan Department of Polymer Engineering National Taiwan University of Science and Technology Taipei 106 Taiwan

The gelation of Pluronic F127 aqueous solution was investigated in the presence of sodium poly(γ-glutamate) (PGA). The gelation temperature was determined based on the tube inversion technique. The gelation temperature increased greatly when the ratio of PGA to F127 was 0.2, and then decreased at higher ratios. The enthalpy of gelation (ΔHgel) was calculated based on the model of Eldridge and Ferry. A splitting in the model was observed when the PGA/F127 ratio was 0.2 which yielded both a maximum and a minimum of ΔHgel. These results indicate that PGA can significantly affect the gelation of F127. Copyright © 2008 John Wiley & Sons, Ltd.

关键词： Enthalpy

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Encapsulation of clay platelets inside latex particles

Encapsulation of clay platelets inside latex particles

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作者： Voorn, D.J. Ming, W. Van Herk, A.M. Laboratories of Polymer Chemistry Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven Netherlands Laboratories of Materials and Interface Chemistry Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven Netherlands P.O. Box 902 5600 AX Eindhoven Netherlands Nanostructured Polymers Research Center Materials Science Program University of New Hampshire Durham NH 03824 United States

ISBN: (纸本)9780841274488

We present our recent attempts in encapsulating clay platelets inside latex particles by emulsion polymerization. Face modification of clay platelets by cationic exchange has been shown to be insufficient for clay encapsulation, leading to armored latex particles. Successful encapsulation of covalently edge-modified clay platelets was achieved via surfactant-free, starved-feed emulsion polymerization. With cryo-TEM and SEM we showed that small Laponite platelets were encapsulated inside spherical latex particles, whereas larger montmorillonite platelets were encapsulated inside dumbbell- like or snowman-like non-spherical latex particles. Covalent bonding of polymerizable groups to the clay platelets proves to be essential for the successful clay encapsulation. © 2009 American Chemical Society.

关键词： Emulsion polymerization

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Environmental effect on the fluorescence lifetime and quantum yield of single extended luminescent conjugated polymers

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Journal of Physical Chemistry C 2009年第43期113卷 18681-18688页

作者： Rassamesard, Areefen Huang, Yi-Fang Lee, Hsu-Yang Lim, Tsong-Shin Li, Ming Chung White, Jonathon David Hodak, Jose Hector Osotchan, Tanakorn Peng, K.Y. Chen, S.A. Hsu, Jui-Hung Hayashi, Michitoshi Fann, Wunshain Institute of Atomic and Molecular Sciences Academia Sinica P.O. Box 23-166 Taipei 106 Taiwan Department of Physics Faculty of Science Mahidol University Rama 6 Rd. Bangkok 10400 Thailand Department of Physics Tunghai University Taichung 407 Taiwan Department of Chemistry National Tsing Hua University Hsinchu 30013 Taiwan Molecular Science and Technology Program Taiwan International Graduate Program Academia Sinica Taipei 115 Taiwan Center for Condensed Matter Sciences National Taiwan University Taipei 106 Taiwan Department of Photonics Engineering Yuan Ze University Taoyuan Taiwan ThEP Center Commission of Higher Education 328 Si Ayuthaya Rd Bangkok 10400 Thailand Department of Chemical Engineering National Tsing Hua University Hsinchu 300 Taiwan Department of Materials and Optoelectronic Science National Sun Yat-sen University Kaohsiung Taiwan Institute of Polymer Science and Engineering National Taiwan University Taipei 106 Taiwan Department of Physics National Taiwan University Taipei 106 Taiwan

To investigate the local environment's effect on the lifetime and quantum yield of extended polymer chains in the absence of intra-and interchain aggregation, short, rodlike polymers of poly(2,5-di-n-octyloxy-1,4- phenylenevinylene) (DO-PPV) were dissolved in chloroform and then embedded in a polystyrene matrix. The fluorescence lifetime was found to increase by 45% in moving from the solution to the matrix form. By using the absorption and emission spectra of the chloroform solution to estimate the radiative and nonradiative rate constants for the polymer in solution, along with calculations based on an exciton model, the corresponding decay rate constants for the polymer embedded in the matrix were obtained. The close agreement between the calculated and experimental values of fluorescent lifetime in the matrix proved the applicability of the exciton model used. On the basis of the model, the average quantum yield of isolated polymers in the matrix was calculated to be a factor of 2 higher than in solutionsan effect arising from a 59% decrease in the nonradiative rate constant and, to a smaller extent, from a 20% increase in the radiative decay rate due to the different dielectric constants of the environments. These results suggest that by extending and isolating single luminescent polymers, high quantum yield devices are possible. © 2009 American Chemical Society.

关键词： Rate constants

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Model compound vulcanization studied by XANES

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Journal of Physics: Conference Series 2009年第1期190卷

作者： W Taweepreda R Nu-Mard W Pattanasiriwisawa P Songsiriritthigul Membrane Science and Technology Research Center Polymer Science Program Faculty of Science Prince of Songkla University Hat-Yai Songkhla 90112 Thailand NANOTEC Center of Excellence at Prince of Songkla University Hat-Yai Songkhla 90112 Thailand Synchrotron Light Research Institute 111 University Avenue Muang Nakhon Ratchasima 30000 Thailand School of Physics Suranaree University of Technology Muang Nakhon Ratchasima 30000 Thailand

Squalene has been used as a model compound for the investigation of sulphur crosslink in the vulcanization process. The effects of the accelerator on the crosslink were deduced from the sulfur K-edge absorption spectra. The majority of the crosslinks for the squalene vulcanized with ZDEC or TMTD is likely disulfidic, while that vulcanized with CBS or MBTS is monosulfidic.

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Erratum to “X-ray and Molecular Modelling Studies on 4-[N-Alkylamino]azobenzene Dyes” [ Dyes Pigments 82 (2009), 299–306]

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Dyes and Pigments 2009年第2期83卷 267-267页

作者： Liang He Ahmed El-Shafei Harold S. Freeman Paul Boyle State Key Laboratory of Fine Chemicals Dalian University of Technology Dalian 116012 PR China Fiber and Polymer Science Program North Carolina State University Raleigh NC 27695-8301 USA Department of Chemistry North Carolina State University Raleigh NC 27695-8204 USA

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Self-replenishing low surface-energy polyurethane films

Self-replenishing low surface-energy polyurethane films

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235th ACS National Meeting, Spring 2008

作者： Dikic, T. Ming, W. Thune, P.C. Tian, M. Van, Benthem, R.A.T.M. De, With, G. Laboratory of Materials and Interface Chemistry Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven Netherlands Schuit Institute of Catalysis Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven Netherlands NT-MDT Europe BV 5674 CC Nuenen Netherlands P.O. Box 902 5600 AX Eindhoven Netherlands Nanostructured Polymer Research Center Materials Science Program University of New Hampshire Durham NH 03824 United States

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Unusual alignment of liquid crystals on rubbed films of polyimides with fluorenyl side groups

Unusual alignment of liquid crystals on rubbed films of poly...

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2007 NSTI Nanotechnology Conference and Trade Show - NSTI Nanotech 2007

作者： Hahm, Suk Gyu Lee, Taek Joon Kim, Dongmin Chang, Taihyun Jung, Jin Chul Zin, Wang-Cheol Ree, Moonhor BK21 Program Polymer Research Institute Pohang University of Science and Technology Pohang 790-784 Korea Republic of

ISBN: (纸本)1420061828

We synthesized two polyimides (PIs), poly(4,4′-(9,9-fluorenyl) diphenylene cyclobutanyltetracarboximide) and poly(4,4′-(9,9-fluorenyl) diphenylene pyromellitimide), and investigated in detail the surface morphology, molecular orientation, and nematic liquid crystal alignments of rubbed PI films. This study found that both the PIs are promising alignment layer materials for the fabrication of advanced LC display devices.

关键词： polymer films

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Synchrotron X-ray scattering studies of star-shape polymers

Synchrotron X-ray scattering studies of star-shape polymers

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2007 NSTI Nanotechnology Conference and Trade Show - NSTI Nanotech 2007

作者： Jin, S. Higashihara, T. Jin, K.S. Yoon, J. Heo, K. Kim, J. Kim, K.-W. Hirao, A. Ree, M. BK21 Program Polymer Research Institute Pohang University of Science and Technology Pohang 790-784 Korea Republic of Polymeric and Organic Materials Department Graduate School of Science and Engineering Tokyo Institute of Technology Tokyo 152-8552 Japan

Shapes and structures of star-polystyrenes bearing 6 to 57-arms were in detail investigated in good and theta solvents by small-angle X-ray scattering with synchrotron radiation sources.

ISBN: (纸本)1420063766

Shapes and structures of star-polystyrenes bearing 6 to 57-arms were in detail investigated in good and theta solvents by small-angle X-ray scattering with synchrotron radiation sources.

关键词： Polystyrenes

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A synchrotron X-ray scattering study on the structure of pepsin in solution

A synchrotron X-ray scattering study on the structure of pep...

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2007 NSTI Nanotechnology Conference and Trade Show - NSTI Nanotech 2007

作者： Jin, K.S. Jin, S. Yoon, J. Heo, K. Kim, J. Kim, H. Ree, M. BK21 Program Polymer Research Institute Pohang University of Science and Technology Pohang 790-784 Korea Republic of Department of Microbiology Dongguk University College of Medicine Gyeongju 780-714 Korea Republic of

ISBN: (纸本)1420061828

Solution small angle X-ray scattering (SAXS) is an effective technique for measuring structure and structural difference of protein under various environments, quantitatively. Structural characteristics of various conformational states of porcine pepsin were studied in terms of size and shape under several pH conditions by solution SAXS. Under nearly physiologically enzymatic active conditions, the reconstructed models exhibit a more extended C-terminal domain, when compare to the crystal structure. The structural differences between solution and crystal structure of pepsin can be accounted for the inherent conformations of the flexible subdomain in the C-terminal domain in solution under carefully controlled specific pH conditions. Furthermore, this flexibility may provide a clue that lead to the solution of enzymatic inactivity of pepsin under mild acidic conditions. The structural evidences presented may have important implication in establishing relationship between the structure of porcine pepsin and its enzymatic function.

关键词： Enzymes

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