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81.
Virgil Percec Anatoliy V. Popov Ernesto Ramirez‐Castillo Oliver Weichold 《Journal of polymer science. Part A, Polymer chemistry》2003,41(21):3283-3299
The first example of living radical polymerization of vinyl chloride carried out in water at 25 °C is reported. This polymerization was initiated by iodoform and catalyzed by nascent Cu0 produced by the disproportionation of CuI in the presence of strongly CuII binding ligands such as tris(2‐aminoethyl)amine or polyethyleneimine. The resulting poly(vinyl chloride) was free of structural defects, had controlled molecular weight and narrow molecular weight distribution, contained two ~CHClI active chain ends, and had a higher syndiotacticity (62%) than the one obtained by conventional free‐radical polymerization at the same temperature (56%). This novel polymerization proceeds, most probably, by a combination of competitive pathways that involves activation by single electron transfer mediated by nascent Cu0 and degenerative chain transfer. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3283–3299, 2003 相似文献
82.
Jianshu Li 《Tetrahedron letters》2005,46(13):2227-2229
The efficient approach for the synthesis of [2,3,6-tri-O-(2-bromo-2-methylpropionyl]-β-cyclodextrin) (21Br-β-CD) is described. The reaction between 2-bromoisobutyric bromide and β-cyclodextrin was performed directly in 1-methyl-2-pyrrolidione solvent, leading to much less complicated procedures and higher yield (up to 89.5%) compared with those reported previously (17% yield). The product is an extremely useful initiator in synthesizing star polymers with well-defined structures using atom transfer radical polymerization for biomedical applications. 相似文献
83.
Nobuhiro Kawatsuki Ryoji Tsutsumi Akie Hiraiwa Hirofumi Takatsuka Takeya Sakai 《Journal of polymer science. Part A, Polymer chemistry》2008,46(14):4712-4718
Thermally enhanced photoinduced in‐plane molecular reorientation in new photo‐cross‐linkable polymer liquid crystalline (PPLC) films comprising 4‐[ω‐(4‐methoxycinnamoyloxy)alkyloxy]biphenyl side groups is explored using linearly polarized ultraviolet (LPUV) light exposure and subsequent annealing. The influence of the alkylene spacer length between the photo‐cross‐linkable group and the biphenyl mesogenic moiety is investigated. The straight‐line characteristics of the photoreactive mesogenic side group and the 4‐methoxycinnamoyl group play important roles in the high photoreactivity and the large thermally enhanced molecular reorientation, where the in‐plane order and the birefringence of the reoriented film are 0.61 and 0.18 are obtained. Finally, cooperative molecular reorientation of dichroic dyes doped in PPLC films is also achieved to fabricate a linear polarizer. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4712–4718, 2008 相似文献
84.
Christian Heller Niklas Pucher Bernhard Seidl Kadiriye Kalinyaprak‐Icten Gerald Ullrich Ladislav Kuna Valentin Satzinger Volker Schmidt Helga C. Lichtenegger Jürgen Stampfl Robert Liska 《Journal of polymer science. Part A, Polymer chemistry》2007,45(15):3280-3291
Intrigued by the good performance of 1,5‐diphenylpenta‐1,4‐diyn‐3‐one ( DPD ) as photoinitiator for radical polymerization we prepared and investigated several donor substituted derivatives. UV‐Vis spectroscopy revealed a gradual red‐shift of λmax and higher extinction in the order of the donor capability. A methoxy‐substituted derivative ( O‐DPD ) exhibited significant photoinitiation activity in photo‐DSC experiments. Steady state photolysis experiments showed decreased decomposition rates with increasing donor capability. A dimethylamino derivative N‐DPD was even photostable under these conditions. Because of to the D‐π‐A‐π‐D system of these compounds two‐photon induced 3D photopolymerization experiments were performed and N‐DPD showed outstanding performance compared to often applied single photon initiators. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3280–3291, 2007 相似文献
85.
S Srinivasa Raghavan 《Pramana》1979,13(2):159-162
The suitability of a soft-core radial wave function in4He calculations is tested by computing the charge form factor of the alpha particle. The free parameter in the radial function
is fixed in a photo-disintegration calculation. The results show that the soft-core function is suitable and the ground state
of4He may be described reasonably well if a suitable potential model is used with it. 相似文献
86.
Chao‐Jian Chen Gong‐Yan Liu Ye‐Ting Shi Cong‐Shan Zhu Shao‐Peng Pang Xiang‐Sheng Liu Jian Ji 《Macromolecular rapid communications》2011,32(14):1077-1081
A novel comb‐like derivative CPEG‐g‐DNQ was prepared by incorporating light responsive 2‐diazo‐1,2‐naphthoquinone (DNQ) groups into the structure of comb‐like poly(ethylene glycol) (CPEG). DLS and TEM results showed that CPEG‐g‐DNQ self‐assembled into spherical micelles with an average size of about 135 nm in water. Upon exposure to light, the micelles could be disrupted because of the conversion of hydrophobic DNQ to hydrophilic 3‐indenecarboylic acid. Additionally, hydrophobic coumarin 102 was successfully loaded into the micelles and photo‐induced ON‐OFF release was demonstrated by fluorescence spectroscopy. MTT assay revealed that the micelles are biocompatible. These photo‐responsive micelles might have great potential for controlled release of hydrophobic drugs.
87.
Jingguo Li Hao Jiang Wenlong Hu Hongyan Xia Gang Zou Qijin Zhang 《Macromolecular rapid communications》2013,34(3):274-279
Herein, we synthesize a coumarin‐substituted diacetylene monomer (CODA) and report the novel photo‐controlled reversible assembly and disassembly behavior of the polymerized CODA (PCODA) vesicles. The photo‐triggered dimerization and cleavage reactions of the coumarin groups within the surface of the adjacent PCODA vesicles can be utilized as the driving force to induce assembly and disassembly of PCODA vesicles. Moreover, the boundary of PCODA vesicles in the aggregates becomes more obscure when the irradiation time exceeds 30 min. Fusion occurs upon close docking of target membranes, driven by sufficient dimerization of the coumarin groups within the surface of PCODA vesicles. 相似文献
88.
Elaheh Rohani Rad Henri Vahabi Krzysztof Formela Mohammad Reza Saeb Sabu Thomas 《先进技术聚合物》2019,30(9):2250-2260
Although significant progress has been made in the design and application of injectable hydrogels for biomedical applications, concurrent control of rheological and mechanical properties of injectable hydrogels has remained as an open challenge to the researchers. In this work, we introduce and put into practice a photo‐curable poloxamer (also known as Pluronic)/graphene oxide (Plu/GO) injectable hydrogel with well‐controlled rheological and mechanical properties. Acrylate group was anchored to hydrogel structure to endow photo‐crosslinking ability through decelerating degradation rate of poloxamer hydrogels after injection. It was found that the modified Plu remains stable in biological media for a long‐term period without significant weight loss. Rheological properties of hydrogels were also carried out as essential prerequisite for an ideal injectability via frequency sweep, flow curve, recovery, and yield stress before and after modification, signifying shear‐thinning behavior of Plu/GO hydrogels with high recoverability. The viscosity of shear‐thinning‐like hydrogels dropped at higher shear stress, which facilitated injection process. Moreover, mechanical behavior of Plu was optimized by manipulating the content of Plu, degree of modification with reactive precursor, curing, and particularly incorporation of GO without deteriorating effects on rheological behavior of Plu. 相似文献
89.
90.
Jae Sang Lee Byung Ho Shin Byoung Yong Yoo Sun‐Young Nam Miji Lee Juhwan Choi Hansoo Park Young Bin Choy Chan Yeong Heo Won‐Gun Koh 《Macromolecular bioscience》2019,19(12)
The surface of poly(dimethylsiloxane) (PDMS) is grafted with poly(acrylic acid) (PAA) layers via surface‐initiated photopolymerization to suppress the capsular contracture resulting from a foreign body reaction. Owing to the nature of photo‐induced polymerization, various PAA micropatterns can be fabricated using photolithography. Hole and stripe micropatterns ≈100‐µm wide and 3‐µm thick are grafted onto the PDMS surface without delamination. The incorporation of PAA micropatterns provides not only chemical cues by hydrophilic PAA microdomains but also topographical cues by hole or stripe micropatterns. In vitro studies reveal that a PAA‐grafted PDMS surface has a lower proliferation of both macrophages (Raw 264.7) and fibroblasts (NIH 3T3) regardless of the pattern presence. However, PDMS with PAA micropatterns, especially stripe micropatterns, minimizes the aggregation of fibroblasts and their subsequent differentiation into myofibroblasts. An in vivo study also shows that PDMS samples with stripe micropatterns polarized macrophages into anti‐inflammatory M2 macrophages and most effectively inhibits capsular contracture, which is demonstrated by investigation of inflammation score, transforming‐growth‐factor‐β expression, number of macrophages, and myofibroblasts as well as the collagen density and capsule thickness. 相似文献