Slightly Cross-Linked Polyrotaxanes Made by Linking [alpha]-Cyclodextrins Entrapped in Polyrotaxanes Using Hexamethylene Diisocyanate

• Published in: Chinese journal of chemistry Vol. 30; no. 10; p. 2453
• Main Authors: Li, Shuo, Wang, Jin, Jiang, Lan, Ye, Lin, Zhang, Aiying, Feng, Zengguo
• Format: Journal Article
• Language: English
• Published: Shanghai Wiley Subscription Services, Inc 01.10.2012
• ISSN: 1001-604X; 1614-7065

In this study polyrotaxane (PR)-based triblock copolymers were first synthesized via the atom transfer radical polymerization (ATRP) of N-isopropylacrylamide initiated with the self-assembly of a distal 2-bromoisobutyryl end-capped Pluronic 17R4 with a varying amount of [alpha]-cyclodextrins ([alpha]-CDs) in the presence of CuCl/PMDETA at 25°C in aqueous solution. The [alpha]-CDs entrapped on the copolymer chain were then linked with hexamethylene diisocyanate to give rise to novel slightly cross-linked polyrotaxanes (SCPRs) in DMF at 45°C. The structures of the PR-based triblock copolymers and SCPRs were characterized by 1H NMR, 13C CP/MAS, GPC and TGA analyses. The number-average molecular weight of the resulting SCPRs was nearly three and five times of their precursor after linking with a low polydispersity index range of 1.08-1.28. The thermo-responsive transition of both PR-based supramolecular polymers in aqueous solution was demonstrated by turbidity measurements and the self-aggregated morphologies were also evidenced by TEM observations. [PUBLICATION ABSTRACT]