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 o...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.展开更多
基金financially supported by the National Natural Scientific Foundation of China (Nos. 20934005 and 21274136)
文摘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.
