Understanding the degradation and mechanical performance of hyperelastic polylactide copolymers through bulk and ultrathin film analysis correlation

Abstract

Appropriate degradation behavior of medical implants is essential, as early degradation of implanted biomaterials can lead to premature loss of mechanical integrity, causing complications such as inflammation and inadequate support during the critical healing period. Therefore, understanding the degradation of newly developed materials for in vivo applications is crucial. Here, we investigated the degradation behavior of blends from Poly[(L-lactide)-co-(ε-caprolactone)] and Poly(D-lactide) (PLLAcoCL/PDLA) in which stereocomplex crystals of the isotactic lactide sequences impart hyperelastic behavior. The PLLAcoCL/PDLA blends were studied through in vitro bulk degradation studies (in printed films and electrospun meshes) and in thin-films using the Langmuir technique. Chemical, thermal, and mechanical properties were assessed at different time-points, highlighting the effects of blends composition and stereocomplexation. The PLLAcoCL/PDLA polymer blend shows promising potential as a covering for expandable cardiovascular implants, offering high ultimate strains (up to >700 %), elasticity, stability, and minimal mass loss during the crucial early healing period (4 weeks). Mechanical data suggest that specific blend ratios, particularly the 95:5 ratio in electrospun meshes, maintained mechanical integrity longer than others (E = 5.7 MPa at week 9), which was reflected in the mass loss of meshes (remaining mass = 67 wt% at week 20). Lower PDLA content accelerated early degradation while enhancing oxidative resistance, whereas higher PDLA content slowed degradation but increased crystallinity. These findings emphasize how blend composition influences degradation rates, mechanical behavior, and stability. Findings highlight the role of composition in tailoring implant degradation and support predictive modeling for cardiovascular applications.