Preparation of Light-Responsive Aliphatic Polycarbonate via Versatile Polycondensation for Controlled Degradation

Starting from (2,2,5-trimethyl-1,3-dioxan-5-yl)methanamine with light-responsive 4,5-dimethoxy-2-nitrobenzyl protecting groups, a variety of light-responsive copolycarbonates (LrPCs) are synthesized by a general two-step polycondensation using lithium acetylacetonate (LiAcac) as catalyst. UV/Vis, H-1 nuclear magnetic resonance (NMR), and size exclusion chromatography (SEC) confirm the rapid decomposition of these polymers in response to irradiation with UV light. Stable and monodisperse nanoparticles with hydrodynamic diameters of 100 nm, formulated from 25% LrPC and 75% poly(lactic-co-glycolic acid) (PLGA), undergo rapid disruption upon triggering with UV light, while standard PLGA nanoparticles remain stable. Moreover, differing from the ring-opening polymerization (ROP) of trimethylene carbonate-based monomers, direct polycondensation of 1,3-propanediol-based monomers with pendent functional groups and other diols will enable the introduction of various properties into the polycarbonate backbone, and expand the family of biodegradable synthetic polymers for potential biomedical applications.