Miktoarm star polymers with poly(N-isopropylacrylamide) or poly(oligo(ethylene glycol) methacrylate) as building blocks: synthesis and comparison of thermally-responsive behaviors

作者：Mu, Cheng-guang; Fan, Xiao-dong^*; Tian, Wei; Bai, Yang; Zhou, Xiang

来源：Polymer Chemistry, 2012, 3(5): 1137-1149.

DOI：10.1039/c2py20029e

• BETA-CYCLODEXTRIN CORES
• DIBLOCK COPOLYMERS
• 2-(2-METHOXYETHOXY)ETHYL METHACRYLATE
• AGGREGATION BEHAVIOR
• CLICK REACTIONS
• COMBINATION
• POLYSTYRENE
• MICELLES
• BRUSHES
• POLYMERIZATION

We synthesized two thermally-responsive miktoarm star polymers in which poly(N-isopropylacrylamide) (PNIPAM) or poly(oligo(ethylene glycol) methacrylate) (POEGMA) served as the thermosensitive building blocks. Firstly, linear methoxypolyethylene glycol (PEG) with beta-cyclodextrin (beta-CD) bearing about six chlorines as a terminal (PEG-CD-Cl-x, x approximate to 6) was synthesized. Then, the thermally-responsive miktoarm star polymer, PEG-CD-PNIPAM(x) or PEG-CD-POEGMA(x), was achieved by atom transfer radical polymerization using N-isopropylacrylamide or oligo(ethylene glycol) methacrylate as the monomer and PEG-CD-Cl-x as the macroinitiator. The obtained miktoarm star polymers were comprised of a beta-CD core, a PEG arm and about six PNIPAM or POEGMA arms. Furthermore, the thermally-responsive behaviors of the miktoarm star polymers were investigated by a combination of UV-vis spectroscopy, DLS, TEM, H-1 NMR, fluorescence spectroscopy and DCS. Above the LCST of the polymers in aqueous solution, PEG-CD-PNIPAM(x) can self-assemble into nano-structures with PNIPAM as the core and PEG as the corona, whereas PEG-CD-POEGMA(x) self-assembled into nano-architectures possessing hydrophilic surfaces which were constructed by the hydrated oligo(ethylene glycol) side chains of the POEGMA arms. The hydrophobic moiety of the nano-architectures was formed by the methacrylate backbone and the dehydrated oligo(ethylene glycol) side chains of POEGMA. Furthermore, it was found that the thermally-induced dehydration of PEG-CD-PNIPAM(x) is completely different from that of PEG-CD-POEGMA(x). For the former, the dehydration occurs abruptly and intensively near the LCST of PEG-CD-PNIPAM(x), whereas the dehydration for the latter is gradual and continuous throughout the whole temperature rise. The architecture of the nano-assemblies formed by PEG-CD-PNIPAM(x) or PEG-CD-POEGMA(x) was affected by the thermally-induced dehydration of the polymers.

• 出版日期2012
• 单位西北工业大学