Controlled one-pot synthesis of pH-sensitive self-assembled diblock copolymers and their aggregation behavior

被引:37
作者
Mao, BW
Gan, LH
Gan, YY
Tam, KC
Tan, OK
机构
[1] Nanyang Technol Univ, Natl Inst Educ, Singapore 637616, Singapore
[2] Nanyang Technol Univ, Sch Mech & Aerosp Engn, Singapore MIT Alliance, Singapore, Singapore
[3] Nanyang Technol Univ, Sch Elect & Elect Engn, Singapore, Singapore
关键词
one-pot ATRP; zwitterionic diblock copolymers; kinetics;
D O I
10.1016/j.polymer.2005.08.048
中图分类号
O63 [高分子化学(高聚物)];
学科分类号
070305 ; 080501 ; 081704 ;
摘要
Diblock copolymers of t-butyl methacrylate (tBMA) and 2-(diethyl ami no)ethyl methacrylate (DEAEMA) were successfully synthesized by one-pot strategy via the atom transfer radical polymerization (ATRP). Kinetic results clearly demonstrated the controlled/'living' character of the polymerization. The zwitterionic block copolymers of poly(methacrylic acid-b-DEAEMA), obtained by hydrolysis of poly(tBMA-b-DEAEMA), showed pH-dependent reverse micellization behavior. Micellar aggregates formed from poly(MAA(30)-b-DEAEMA(71)), poly(MAA(68)-b-DEAEMA(55)) and poly(MAA(64)-b-DEAEMA(44)) had fairly low polydispersity index at both solutions of low pH of 2 and high pH of 12. Micelles formed at pH 2 were larger (R-h similar to 40-61 nm) with looser core due to hydration of the MAA. In the presence of simple electrolyte (0.3 mol dm(-3) NaCl solution), the size of the micelles reduced by almost half while the aggregation number was little changed. This is attributed to the draining of the hydrated micellar core due to osmotic pressure. On the other hand, DEAEMA-core micelles formed at pH 12 were compact and much smaller (R-h similar to 14-22 nm). Addition of NaCl had only a small effect. The micellar size reduced only slightly due to the electrostatic screening effect and the aggregation number was almost unchanged. (c) 2005 Elsevier Ltd. All rights reserved.
引用
收藏
页码:10045 / 10055
页数:11
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