The. Thermosensitivity Parents Synthesis And Characterization Of Water Polypeptide Block Polymer

In this paper, a series of well-defined, thermoresponsive double hydrophilic peptide copolymers which consist of thermoresponsive poly(N-isopropylacrylamide) (PNIPAAm) and poly(L-glutamate) (PLGA) were synthesized by using Reversible Addition-Fragmentation chain Transfer radical polymerization (RAFT) and Ring Opening Polymerization (ROP) of the N-carboxyanhydride of γ-benzyl-L-glutamate via methods of the macroinitiators and macro chain transfer agents.A new type of trithiocarbonates RA-2 with amide protected in its leaving group as the RAFT agent was synthesized and two methods were applied. 1) Macroinitiators route. The thiocarbonate terminated PNIPAAm was synthesized by RAFT process controlled by RA-2, and the polymer was treated with trifluoroacetic acid to remove the protecting group of the amide, and the resulting macroinitiator PN-NH₂ was used to initiated the polymerization of N-carboxyanhydride of γ-benzyl-L-glutamate (NCA of Glu) to get the amphiphilic copolymer PN-b-PBLG. The double hydrophilic copolymer PN-b-PLGA was synthesized after the removal of the benzyl group from the PBLG block by the HBr/Glacial acetic acid. 2) Macro chain, transfer agents route. RA-2 was firstly treated with trifluoroacetic acid to remove the protecting group of amide, and this new initiator RA-3 was used to initiate the polymerization of NCA of Glu to prepare the peptide with thiocarbonate end capped as the macro chain transfer agents (Macro-CTA). The PBLG-b-PN was synthesized by the polymerization of N-isopropylacrylamide in RAFT process controlled by this Macro-CTA. The PLGA-b-PN can be synthesized in the same way mentioned above. It was found that the macroinitiator route was the better choice from the GPC results of the copolymer.The thermoresponsivity (Lower Critical Solution Temperature, LCST), CMC (Critical Micellar Concentration), and its self-assembly in water were...