Accelerating polycaprolactone degradation through bottlebrush architecture

Controlling degradation kinetics and pathways in polymeric materials typically relies on altering chemical composition, often coupling degradation behavior to changes in mechanical and thermal properties. Here, we show that molecular architecture provides an alternative route to degradation control without modifying the underlying chemistry. Using bottlebrush polycaprolactone (PCL) elastomers with systematically varied side-chain lengths, we tune crystallinity, melting temperature, and solvent accessibility to regulate degradation kinetics and pathways independently of chemical composition. Compared to rigid, highly crystalline linear PCL analogs, bottlebrush architecture suppresses crystallization, lowers the melting temperature, and accelerates degradation through surface erosion. Incorporation of a controlled fraction of hydrophilic polyethylene glycol (PEG) side chains introduces a complementary mechanism for tuning degradation by enhancing water uptake and inducing a transition from surface to bulk erosion. X-ray scattering and coarse-grained molecular dynamics simulations reveal distinct degradation pathways in pure PCL and PCL-PEG bottlebrushes, arising from limited versus enhanced solvent penetration and the corresponding differences in network fragmentation. At physiological temperature, these materials exist in a melt state and exhibit soft elastic moduli (∼10-100 kPa). Together, these findings establish bottlebrush architecture as a general molecular design strategy for independently regulating degradation kinetics, erosion mode, and mechanical properties in degradable polymer materials.