私密直播全婐app免费大渔直播,国产av成人无码免费视频,男女同房做爰全过程高潮,国产精品自产拍在线观看

當前位置:群英聚首 > 論文著作 > 正文
Preparation of Primary Amine-Based Block Copolymer Vesicles by Direct Dissolution in Water and Subsequent Stabilization by Sol-Gel Chemistry
來源:杜建忠教授個人網站 發布日期:2010-03-08
作者:Jianzhong Du* and Steve Armes
關鍵字:polymer vesicles, self-assembly
論文來源:期刊
具體來源:Langmuir 2008, 24, 13710-13716.
發表時間:2008年

A new amphiphilic biocompatible diblock copolymer, poly(ε-caprolactone)-block-poly(2-aminoethyl methacrylate), PCL-b-PAMA, was synthesized in three steps by (i) ring-opening polymerization of ε-caprolactone, (ii) end-group modification by esterification, and (iii) atom transfer radical polymerization (ATRP) of 2-aminoethyl methacrylate hydrochloride (AMA) in its hydrochloride salt form. This copolymer forms block copolymer vesicles with the hydrophobic PCL block forming the vesicle membrane. Unusually, these vesicles are easily prepared by direct dissolution in water without using organic co-solvents, pH adjustment, or even stirring. These vesicles can be stabilized by aqueous sol−gel chemistry using tetramethyl orthosilicate (TMOS) as the silica precursor. It is well-known that cationic polymers can catalyze silica formation, but in this particular case, it seems that the TMOS precursor is solubilized within the hydrophobic PCL membrane. Thus, the neutral membrane actually directs silica formation, rather than the cationic PAMA chains. The final vesicle morphology and the silica content depend on the silicification conditions. Provided that the TMOS/AMA molar ratio does not exceed 10:1, silicification is solely confined within the PCL membrane. At higher ratios, silica nanoparticles (5−12 nm) are also observed on the outer surface of the silicified vesicles. However, these nanoparticles appear to be only weakly adsorbed, since they can be easily removed by dialysis. The mean hydrodynamic diameter of the silicified vesicles varies from 175 to 205 nm with solution pH due to (de)protonation of the externally expressed PAMA chains. Calcination of the silicified vesicles at 800 °C leads to the formation of hollow silica particles. 1H NMR, transmission electron microscopy (TEM), dynamic light scattering (DLS), aqueous electrophoresis, and thermogravimetric analysis (TGA) were employed to characterize the vesicles, both before and after silicification.

http://pubs.acs.org/doi/abs/10.1021/la8025123?prevSearch=%255Bauthor%253A%2Bjianzhong%2Bdu%255D&searchHistoryKey=

Copyright © 2005 Polymer.cn All rights reserved
中國聚合物網 版權所有
經營性網站備案信息

京公網安備11010502032929號

工商備案公示信息

京ICP證050801號

京ICP備12003651號

主站蜘蛛池模板: 武鸣县| 广饶县| 龙井市| 余姚市| 车险| 峨边| 和顺县| 贵定县| 芒康县| 海阳市| 修文县| 大理市| 从化市| 故城县| 铁岭县| 博乐市| 新余市| 苍溪县| 石阡县| 湘潭县| 平武县| 武汉市| 石景山区| 道孚县| 皋兰县| 锦屏县| 安西县| 高清| 天台县| 平果县| 西昌市| 蛟河市| 临城县| 江油市| 富阳市| 灵山县| 岢岚县| 台东市| 宜春市| 陇川县| 鄂尔多斯市|