Using Host-Guest Chemistry to Tune the Kinetics of Morphological Transitions Undertaken by Block Copolymer Vesicles

Host-guest chemistry is exploited to tune the rate at which block copolymer vesicles undergo morphological transitions. More specifically, a concentrated aqueous dispersion of poly(glycerol monomethacrylate-co-glycidyl methacrylate)-poly(2-hydroxypropyl methacrylate) [P(GMA-co-GlyMA)-PHPMA] diblock copolymer vesicles was prepared via polymerization-induced self-assembly (PISA). The epoxy groups in the GlyMA residues were ring-opened using a primary amine-functionalized β-cyclodextrin (NH₂-β-CD) in order to prepare β-CD-decorated vesicles. Addition of azobenzene-methoxypoly(ethylene glycol) (azo-mPEG) to such vesicles results in specific binding of this water-soluble macromolecular reagent to the β-CD groups on the hydrophilic P(GMA-co-GlyMA) stabilizer chains. Such host-guest chemistry induces a morphological transition from vesicles to worms and/or spheres. Furthermore, the rate of this morphological transition can be tuned by UV/visible-light irradiation and/or guest molecule competition. This novel molecular recognition strategy offers considerable scope for the design of new stimulus-responsive diblock copolymer vesicles for targeted delivery and controlled release of cargoes.