SYSTHESIS OF DOUBLE-HYDROPHILIC CORE-SHELL TYPE MULTIARM STAR COPOLYMER POLYETHYLENIMINE-block-POLY（2-HYDROXYETHYL METHACRYLATE）

• Published in: Chinese journal of polymer science Vol. 31; no. 7; pp. 1046 - 1055
• Main Authors: Tang, Qiang, Cheng, Fa, Cui, Jin, Chen, Yu
• Format: Journal Article
• Language: English
• Published: Heidelberg Chinese Chemical Society and Institute of Chemistry, CAS 01.07.2013
• Subjects: Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Condensed Matter Physics; GPC; Industrial Chemistry/Chemical Engineering; Polymer Sciences; 化学; 化学分子式; 高分子化学; Atom transfer radical polymerization; Star polymers; Polyethylenimine; Hyperbranched; Poly(2-hydroxyethyl methacrylate)
• ISSN: 0256-7679; 1439-6203
• DOI: 10.1007/s10118-013-1298-4

Multiarm star block copolymers hyperbranched polyethylenimine-b-poly（2-hydroxyethyl methacrylate） （HPEI-b- PHEMA） with average 28 PHEMA arms have been prepared by atom transfer radical polymerization （ATRP） of HEMA in a mixed solvent of methanol and water using a core-first strategy. The hyperbranched macroinitiator employed was prepared on the basis of well-defined hyperbranched polyethylenimine with Mw/Mn of 1.04 by amidation with 2-bromo-isobutyryl bromide. The polymerization condition was optimized to prepare star copolymers with narrow dispersity, and the variables included the volume ratio of methanol to water, the molar ratio of initiating site to CuC1 and the molar ratio of [CuCl]：[CuBr2]. Under the optimized polymerization condition, the lowest Mw/Mn value of the obtained star copolymers was around 1.3. Kinetic analysis showed that an induction period existed in the polymerization of HEMA. After this induction period, a linear dependence of ln（[M]0/[M]t） on time was observed. The obtained HPEI-b-PHEMA could adsorb hydrophilic molecules. The comparison with the star copolymer with hydrophobic core and hydrophilic PHEMA shell verified that both the hydrophilic core and shell could host the hydrophilic guests, but the amidated HPEI core was more effective than the PHEMA shell.