Vesicle-templated pH-responsive polymeric nanocapsules

We report the synthesis of pH responsive polymeric nanocapsules by templating unilamellar vesicles of dimethyldioctadecylammonium bromide (DODAB) using a RAFT-based templating approach. A short-chain living anionic copolymer containing randomly distributed acrylic acid and butyl acrylate units was first synthesized by RAFT in solution using dibenzyl trithiocarbonate (DBTTC) as the RAFT agent. The anionic copolymer chains were subsequently adsorbed onto the surface of cationic DODAB vesicles and were further chain extended to form a thick polymeric shell by feeding a monomer mixture comprising methyl methacrylate (MMA) and tertiary butyl acrylate (t-BA) in combination with the divinyl crosslinker ethylene glycol dimethacrylate (EGDMA) under starved feed conditions. CryoTEM characterization demonstrated successful formation of a thick crosslinked polymeric shell around the vesicles. Subsequent acid hydrolysis of the tertiary butyl ester groups of the crosslinked polymeric shell resulted in the formation of pH-responsive nanocapsules.