Inverse Cross‐Link‐Density/Activation‐Energy Coupling in Poly(lactic acid) Dual‐Dynamic Networks for Creep‐Resistant Reprocessability and Reconfigurable Multi‐Shape Memory Toward Adaptive Medical Devices
Zhaoyang Wang, Xiuping Liu, Xingjian LiABSTRACT
Developing degradable poly(lactic acid) (PLA) covalent adaptable networks that simultaneously integrate mechanical robustness, creep resistance, reprocessability, and tunable multi‐shape memory remains a major challenge, particularly when low‐molecular‐weight PLA is used as the sustainable precursor. Here, we report a poly(lactic acid) dual‐dynamic network with inverse cross‐link‐density/activation‐energy coupling constructed through a facile one‐pot reaction of commercially available PLA diols, hexamethylene diisocyanate trimer, and 2,2′‐diaminodiphenyl disulfide (DADS). The network architecture couples a densely cross‐linked disulfide‐containing dynamic network with low activation energy (E a ) and a loosely cross‐linked PLA‐rich dynamic network with high E a . The dense low‐E a network provides mechanical reinforcement, low‐temperature stability, and rapid thermally activated rearrangement, whereas the loose high‐E a network contributes extensibility, creep resistance, elastic energy storage, and high‐temperature processability. By regulating PLA molecular weight and DADS/PLA ratio, the dual‐dynamic networks show tunable glass transition, degradation rate, and rearrangement kinetics. Such unique hierarchical dual‐dynamic network architecture with inverse cross‐link‐density/activation energy coupling endows the material with prominent stiff‐toughness, reprocessability, creep resistance, and reconfigurable multi‐shape memory capability. Moreover, adaptive medical fixation and photothermal‐assisted therapeutic prototypes demonstrate the potential of these reconfigurable shape memory PLA networks with cytocompatibility for sustainable biomedical devices.