Synthesis and self-assembly of poly(n-isopropylacrylamide)-b-poly (epsilon-benzyloxycarbonyl-l-lysine)-b-poly(ethylene glycol)
文献类型：期刊论文
| 作者 | Zhao Changwen1,2; Zhuang Xiuli1; Chen Xuesi1; Jing Xiabin1 |
| 刊名 | Acta polymerica sinica
 |
| 出版日期 | 2008-11-20 |
| 期号 | 11页码:1096-1101 |
| 关键词 | Poly(n-isopropylacrylamide) Poly(3-benzyloxycarbonyl-l-lysine) Mpeg Temperature sensitivity Micelle Self-assembly |
| ISSN号 | 1000-3304 |
| 通讯作者 | Zhao changwen() |
| 英文摘要 | A novel amphiphilic and thermosensitive triblock copolymer of poly( n-isopropylacrylamide)-b-poly(3-benzyloxycarbonyl-l-lysine)-b-poly(ethylene glycol) (pnipam-b-pzll-b-mpeg) with designed molecular weight and narrow molecular weight distribution was prepared. synthetic procedure included the following steps. (1) amino-terminated pnipam was synthesized via the free radical polymerization of nipam in methanol using 2,2'-azobisiso-butyronitrile (aibn) and 2-aminoethanethiol hydrochloride (aet center dot hcl) as the initiator and chain transfer agent, respectively. its molecular weight was calculated by the h-1-nmr spectra in d2o. (2) the block copolymers, pnipam-b-pzll were synthesized by the ring-opening polymerization (rop) of 3-benzyloxycarbonyl-l-lysine n-carboxyanhydride (z-lys-nca) with pnipam-nh2 as a macroinitiator. their structure was confirmed by the h-1-nmr spectra. the molecular weight and molecular weight distribution of pnipam-b-pzll were characterized by gpc analysis in thf. the relatively narrow polydispersity of the obtained pnipam-b-pzll could be explained by the living character of the rop of ncas initiated by primary amine hydrochlorides which avoided the side reaction called "active monomer" mechanism. generally, the molecular weights could be controlled by the feed molar ratios of monomer to maroinitiator. (3) for preparing the triblock polymers, pnipam-b-pzll-b-mpeg, it was necessary to convert the terminal hydroxyl group of mpeg of different molecular weight (2000 or 5000) into carboxyl group by succinic anhydride. its h-1-nmr spectra showed this was a high efficiency reaction. then the triblock copolymers were obtained by the condensation reaction between carboxyl-capped mpeg and amino-capped pnipam-b-pzll in the presence of dicyclohexylcarbodiimide (dcc) and 4-dimethylaminopyridine (dmap). the h-1-nmr confirmed their structure. based on the integration ratio, their relative amount in the copolymer was calculated. and their m-n (nmr) agreed well with the theoretical number-average molecular weight. gpc analysis in thf revealed a monomodal and symmetric peak which showed the successful synthesis of target copolymers. all the molecular weight distributions (m-n/m-n = 1.11 similar to 1.20) were relative narrow. the triblock copolymer could self-assemble into micelles in aqueous solution with hydrophobic pzll as the core and hydrophilic pnipam and mpeg as the corona. its critical micelle concentration (cmc) was measured by a fluorescence spectra technique using pyrene as a probe. the cmc decreased with the increase of pzll content and increased with the increase of peg content. dynamic light scattering (dls) analyses of triblock copolymer micelles reavealed their size of less than 100nm and narrow size distribution. it is well-known that pnipam homopolymer dissolved in cold and dilute aqueous solution but gets insoluble at ca. 32 degrees c due to its lower critical solution temperature (lcst) phase behavior. when the temperature was above the lcst, the pnipam undergoes a reversible phase transition caused by the coil-to- globule transition and becomes more hydrophobic. so changing temperature will influence the stability of micelles. as anticipated, the micelles aggregated at temperature above lcst when the m-n of mpeg was 2000. that is probably that the mpeg2000 could not prevent the intermicellar hydrophobic interaction. however, no obvious aggregation of micelles was found at temperatures above lcst when the m-n of mpg was 5000 because the hydrophobic interaction between the micelles was prevented by mpeg5000 effectively. |
| WOS关键词 | DIBLOCK COPOLYMER ; BLOCK-COPOLYMERS ; N-CARBOXYANHYDRIDES ; POLYMERIZATION ; TEMPERATURE |
| WOS研究方向 | Polymer Science |
| WOS类目 | Polymer Science |
| 语种 | 英语 |
| WOS记录号 | WOS:000260878600012 |
| 出版者 | SCIENCE CHINA PRESS |
| URI标识 | http://www.irgrid.ac.cn/handle/1471x/2391695 |
| 专题 | 中国科学院大学 |
| 通讯作者 | Zhao Changwen |
| 作者单位 | 1.Chinese Acad Sci, Changchun Inst Appl Chem, State Key Lab Polymer Chem & Phys, Changchun 130022, Peoples R China 2.Chinese Acad Sci, Grad Sch, Beijing 100039, Peoples R China |
| 推荐引用方式 GB/T 7714 | Zhao Changwen,Zhuang Xiuli,Chen Xuesi,et al. Synthesis and self-assembly of poly(n-isopropylacrylamide)-b-poly (epsilon-benzyloxycarbonyl-l-lysine)-b-poly(ethylene glycol)[J]. Acta polymerica sinica,2008(11):1096-1101. |
| APA | Zhao Changwen,Zhuang Xiuli,Chen Xuesi,&Jing Xiabin.(2008).Synthesis and self-assembly of poly(n-isopropylacrylamide)-b-poly (epsilon-benzyloxycarbonyl-l-lysine)-b-poly(ethylene glycol).Acta polymerica sinica(11),1096-1101. |
| MLA | Zhao Changwen,et al."Synthesis and self-assembly of poly(n-isopropylacrylamide)-b-poly (epsilon-benzyloxycarbonyl-l-lysine)-b-poly(ethylene glycol)".Acta polymerica sinica .11(2008):1096-1101. |
入库方式： iSwitch采集
来源：中国科学院大学
浏览0
下载0
收藏0
其他版本
除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。