Polylactide (PLA) and poly(DL-lactide-co-glycolide) (PLGA) are two prominent FDA-approved polymers because of their useful biodegradation into largely innocuous substances. Their hydrolytic degradation is slow and offers minimal control over degradation kinetics, especially in the minutes time scale. However, molecular engineering of their structures could allow triggered degradation. We have synthesized, by ring-opening polymerization (ROP), a series of PLGA-based polymers containing pendant nucleophiles protected with photodeavable groups. Upon deprotection, two of the polymers degrade rapidly via intramolecular cyclization into small molecules. Nanoparticles formulated from these polymers undergo rapid structural changes in response to UV light. This work introduces a novel polymeric structure to enable rapid on-demand degradation and expands the library of polymers that degrade by cyclization.