Therrno-responsive block copolymers poly(ethylene glycol)-block-poly(N-acryloyl-2,2-dimethyl-1,3-oxazolidine), PEG-b-PADMO, based on linear PEG were prepared via a versatile reversible addition-fragmentation chain...Therrno-responsive block copolymers poly(ethylene glycol)-block-poly(N-acryloyl-2,2-dimethyl-1,3-oxazolidine), PEG-b-PADMO, based on linear PEG were prepared via a versatile reversible addition-fragmentation chain transfer (RAFT) polymerization, PEG22 (Mw = 1000) was used as the hydrophilic component, whose dehydration was the main driving force for the phase transition of these copolymers, as demonstrated by the tH-NMR spectra. Their lower critical solution temperatures (LCSTs) could be tuned in the range of 20℃ to 35℃, by adjusting the degree of polymerization (DP) of PADMO between 14-27. Furthermore, a sharp phase transition at ca. 33℃, close to the physiological temperature with minimal hysteresis, was observed for the PEGzz-b-PADMO14 copolymer. Moreover, excellent reversibility and reproducibility were displayed for the same copolymer over 10 cycles of repeated temperature change between 25℃ (below the LCST) and 40℃ (above the LCST).展开更多
文摘Therrno-responsive block copolymers poly(ethylene glycol)-block-poly(N-acryloyl-2,2-dimethyl-1,3-oxazolidine), PEG-b-PADMO, based on linear PEG were prepared via a versatile reversible addition-fragmentation chain transfer (RAFT) polymerization, PEG22 (Mw = 1000) was used as the hydrophilic component, whose dehydration was the main driving force for the phase transition of these copolymers, as demonstrated by the tH-NMR spectra. Their lower critical solution temperatures (LCSTs) could be tuned in the range of 20℃ to 35℃, by adjusting the degree of polymerization (DP) of PADMO between 14-27. Furthermore, a sharp phase transition at ca. 33℃, close to the physiological temperature with minimal hysteresis, was observed for the PEGzz-b-PADMO14 copolymer. Moreover, excellent reversibility and reproducibility were displayed for the same copolymer over 10 cycles of repeated temperature change between 25℃ (below the LCST) and 40℃ (above the LCST).