Facile synthesis of low-polydispersity block copolymer vesicles by azide-zwitterion cycloaddition

Polycaprolactone with azide (PCL-N3) and polyethylene glycol with α,β-unsaturated ester (maPEG) as chain-end functional group were synthesized, respectively. Then, facile synthesis of polycaprolactone-block-polyethylene glycol (PCL-b-PEG) amphiphilic copolymer by azide-zwitterion cycloaddition of PCL-N3 and maPEG, as the first example, was reported. The self-assembly of this amphiphilic copolymer was carried out in deionized water, and then the formation of vesicles was proven by the result of transmission electron microscope (TEM). Grainsize analyzer suggested that the diameter of the vesicles is 305 nm in average and the polydispersity of the vesicles is 0.128. The azide-zwitterion cycloaddition provides a powerful method for the post-functionalization of α,β-unsaturated ester or azide end-functionalized polymers.