A pH-responsive amphiphilic supramolecular graft copolymer constructed by crown ether based molecular recognition

Graft polymers always play a significant role in polymer chemistry as they are preferred materials for a large variety of applications, such as drug/gene delivery systems, hybrid and biomedical materials, soft rubbers, and opto-electronic materials. Compared with traditional graft copolymers, supramolecular graft copolymers whose main chains and side chains are connected by non-covalent forces (e. g. hydrogen bonding, metal-coordination, host-guest interactions, etc.), could be easily obtained in a facile and dynamic manner instead of tedious and time-consuming synthesis. Herein, based on the BMP32C10/paraquat molecular recognition in water, we have successfully prepared an amphiphilic supramolecular graft copolymer by synthesizing poly(styrene-coparaquat) 1 as the hydrophobic main chain and modified poly(ethylene oxide) 2 as the hydrophilic side chains. The self-assembly behaviour of the amphiphilic supramolecular graft copolymer in water was investigated by DLS, TEM and SEM. As confirmed, it could selfassemble into bilayer vesicles in water, which would be destroyed with the treatment of HCl. Therefore, the vesicles were further used in the pH controlled release of water-soluble molecules.