Synthesis and Self-Assembly of o-Nitrobenzyl-Based Amphiphilic Hybrid Polymer with Light and pH Dual Response

In this paper, novel light-responsive polyhedral oligomeric silsesquioxane (POSS) end-capped poly(o-nitrobenzyl methacrylate) (POSS-PNBMA) are synthesized by the combination of atom transfer radical polymerization (ATRP) and click chemistry. After subsequent partial photocleavage of PNBMA yielding poly(methacrylic acid) (PMAA), pH- and light-responsive random copolymer of POSS-P(NBMA-co-MAA) is obtained. The o-nitrobenzyl-based amphiphilic hybrid polymer can self-assemble into spherical micelles in aqueous solution. Hydrophobic POSS and PNBMA segments aggregate into the inner core, and the hydrophilic PMAA chains tend to stretch from the core. The micellar morphology can be tuned by pH changes and UV irradiation. Light irradiation leads to the transformation of P(NBMA-co-MAA) into PMAA and to the reorganization of the assemblies, causing the release of encapsulated guest molecule Nile Red into water. This dual-responsive polymer has a broad potential use in targeted drug delivery.