Fabrication of Crosslinked Poly(L-lactic acid) with Enhanced Shape Memory Performance via γ-Ray Irradiation.

In this work, an innovative approach has been established to overcome the intrinsic limitations of poly(L-lactic acid) (PLLA)-based shape memory polymers (SMPs) by introducing γ-ray-induced crosslinking in miscible PLLA/triallyl isocyanurate (TAIC) blends. The crosslinking density can be precisely adjusted by the TAlC content and absorbed irradiation dose, enabling the fabrication of PLLA SMPS with outstanding shape memory properties. In crosslinked PLLA SMPs, the crosslinking point can significantly suppress the cold crystallization and prevent the irreversible chain slippage during deformation in the shape memory process, resulting in not only a high shape recovery ratio (99.5% at 10 wt% TAIC) but also a good cycle stability (maintaining 97.9% after three cycles). Moreover, the crosslinking points as well as the PLLA crystals endow PLLA with triple-shape memory performance, in which both the glass transition temperature and melting temperature serve as switch conditions. Remarkably, even under extreme deformation conditions (strain up to 800%), the crosslinked PLLA SMPs maintain a recovery ratio as high as 99.3%. Our results offer a novel strategy for fabricating high-performance PLLA SMPs with exceptional shape recovery capabilities.