CLICK CYCLIZATION OF LINEAR TRIBLOCK COPOLYMERS AT BLOCK JUNCTIONS UNDER HIGH CONCENTRATION DUE TO E

• 作 者: Jing Tao Bang-kun Jin Li-ying Li Chen He 何卫东
• 机 构: CAS Key Laboratory of Soft Matter Chemistry,Department of Polymer Science and Engineering,University
• 出 处: Chinese Journal of Polymer Science
• 发表日期: 2013年07期
• 关键词: PNIPAM azide click blocks glycol shaped polymerization chains linearly cyclizati

Linear triblock copolymers of poly(N-isopropylacrylamide) (PNIPAM) and poly(ethylene glycol) (PEG) with two azide groups at both block junctions (PNIPAM-N3-PEG-N3-PNIPAM) are click reacted with dipropargyl oxalylate under high polymer concentration (250 g/L). Benefiting from rapid feature of alkyne-azide click reaction and spatial shielding of PNIPAM end blocks, PEG center block of PNIPAM-N3-PEG-N3-PNIPAM remains separated although PNIPAM end blocks keep in contact under this high concentration. Therefore, PNIPAM-N3-PEG-N3-PNIPAM undergoes self-cyclization at block junctions to form tadpole-shaped architecture while N3-PEG-N3 without PNIPAM end blocks inter-connects linearly. The influence of block lengths of PEG and PNIPAM on the unusual cyclization under high polymer concentration is studied.

Linear triblock copolymers of poly (N-isopropylacrylamide) (PNIPAM) and poly (ethylene glycol) (PEG) with two azide groups at both block junctions (PNIPAM-N3-PEG-N3- PNIPAM) are click reacted with dipropargyl oxalylate under high polymer concentration (250 g / L). Benefiting from rapid feature of alkyne-azide click reaction and spatial shielding of PNIPAM end blocks, PEG center block of PNIPAM-N3-PEG-N3- PNIPAM-N3-PEG-N3-PNIPAM undergoes self-cyclization at block junctions to form tadpole-shaped architecture while N3-PEG-N3 without PNIPAM end blocks inter-connects linearly. The influence of block lengths of PEG and PNIPAM on the unusual cyclization under high polymer concentration is studied.