Stimulus-responsive block copolymer nano-objects and hydrogels via dynamic covalent chemistry

摘要

Herein we demonstrate that dynamic covalent chemistry can be used to induce reversible morphologicaludtransitions in block copolymer nano-objects and hydrogels. Poly(glycerol monomethacrylate)–poly(2-udhydroxypropyl methacrylate) (PGMA–PHPMA) diblock copolymer nano-objects (vesicles or worms) wereudprepared via polymerization-induced self-assembly. Addition of 4-carboxyphenylboronic acid (CPBA)udleads to the formation of phenylboronate ester bonds with the 1,2-diol pendent groups on theudhydrophilic PGMA stabilizer chains; such binding causes a subtle reduction in the packing parameter,udwhich in turn induces either vesicle-to-worm or worm-to-sphere transitions. Moreover, CPBA binding isudpH-dependent, so reversible transitions can be achieved by switching the solution pH, with relatively highudcopolymer concentrations leading to associated (de)gelation. This distinguishes these new physicaludhydrogels from the covalently cross-linked gels prepared using dynamic covalent chemistry reported inudthe literature.