文献名： Self-crosslinking assemblies with tunable nanostructures from photoresponsive polypeptoid-based block copolymers

作者： Jirui Wei,  Jing Sun,  Xu Yang,  Sifan Ji,  Yuhan Wei  and  Zhibo Li

Key Laboratory of Biobased Polymer Materials, Shandong Provincial Education Department, School of Polymer Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, China

摘要：Photoresponsive polymers have been receiving tremendous attention for many applications. Here, we report a new family of photoresponsive polypeptoid-based diblock copolymers PEG-b-poly(N-(S-(o-nitrobenzyl)-thioethyl) glycine) (PEG-b-PNSN) by ring-opening polymerization (ROP). The polymerization is well-controlled and a series of copolymers have been obtained with narrow polydispersity. We demonstrate that the cleavage degree of the o-nitrobenzyl (NB) group can reach 73% with the irradiation time increasing up to 6 hours. To the best of our knowledge, this is the first example of photoresponsive polypeptoids prepared by ROP. Depending on the chain length of PNSN, the PEG-b-PNSN diblock copolymers can self-assemble into various morphologies, including spheres, short cylinders and vesicles. More importantly, the thiol groups generated by UV-irradiation can be spontaneously oxidized into disulfide bonds, which behave as cross-linkers to stabilize the nanostructures with constant morphologies. Furthermore, this oxidation process is reversible in the presence of the reductive reagent glutathione (GSH), resulting in reversible self-crosslinking assemblies. The obtained photoresponsive polypeptoid copolymers are ideal candidates for smart polymeric materials in applications of nanomedicine and nanotechnology.