Light-Programmable Polyester Networks with Movable Cross-Links for On-Demand Enzymatic Degradation

The design of sustainable materials that integrates mechanical toughness with on-demand degradability remains a central challenge in the development of materials science. Here, we present a photoresponsive polyester capable of light-regulated enzymatic degradation through movable cross-links. The material consists of a poly(ε-caprolactone) backbone and inclusion complexes between photoisomerizable <i>trans</i>-stilbene (<i>t</i>Sti) units and triacetylated γ-cyclodextrin (TAcγCD) units. Upon UV-A (<i>λ</i> = 350 nm) or UV-C (<i>λ</i> = 254 nm) irradiation, stilbene units undergo reversible <i>trans</i>-<i>cis</i> isomerization, repositioning cyclodextrin (CD) rings along the backbone and thereby switching the molecular coverage of enzyme-active ester groups. In the <i>trans</i> state, polyester segments are exposed, accelerating lipase-catalyzed degradation; in the <i>cis</i> state, ester groups are shielded, suppressing degradation. The switching is reversible under alternating UV-A/UV-C irradiation and absent in the linear control lacking movable rings, demonstrating that controllable CD positioning is essential for degradation control. This study introduces a molecular-coverage-based design rule that reconciles toughness and degradability for sustainable, environmentally benign polymers.