Self-assemblies of ?-CDs with pentablock copolymers PMA-PPO-PEO-PPO-PMA and endcapping via atom transfer radical polymerization of 2-methacryloyloxyethyl phosphorylcholine.

ABSTRACT: Pentablock copolymers PMA-PPO-PEO-PPO-PMA synthesized via atom transfer radical polymerization (ATRP) were self-assembled with varying amounts of ?-CDs to prepare poly(pseudorotaxanes) (PPRs). When the concentration of ?-CDs was lower, the central PEO segment served as a shell of the micelles and was preferentially bent to pass through the ?-CD cavity to construct double-chain-stranded tight-fit PPRs characterized by a channel-like crystal structure. With an increase in the amount of ?-CDs added, they began to accommodate the poly(methyl acrylate) (PMA) segments dissociated from the core of the micelles. When more ?-CDs were threaded and slipped over the segments, the ?-CDs were randomly distributed along the pentablock copolymer chain to generate single-chain-stranded loose-fit PPRs and showed no characteristic channel-like crystal structure. All the self-assembly processes of the pentablock copolymers resulted in the formation of hydrogels. After endcapping via in situ ATRP of 2-methacryloyloxyethyl phosphorylcholine (MPC), these single-chain-stranded loose-fit PPRs were transformed into conformational identical polyrotaxanes (PRs). The structures of the PPRs and PRs were characterized by means of (1)H NMR, GPC, (13)C CP/MAS NMR, 2D (1)H NOESY NMR, FTIR, WXRD, TGA and DSC analyses.

SUBMITTER: Lin J 

PROVIDER: S-EPMC4685896 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature