UV-Mediated Facile Fabrication of a Robust, Fully\nRenewable and Controllably Biodegradable Poly(lactic acid)-Based Covalent\nAdaptable Network

A robust\nand fully biobased covalent adaptable network (CAN) that\nallows recyclability, biocompatibility, and controlled biodegradability\nis reported. The CAN was fabricated through a simple photo-cross-linking\nmethod, wherein low-molecular-weight poly(lactic acid) (∼3\nkDa) was modified with end 1,2-dithiolane rings through a one-step\nSteglich esterification reaction with thioctic acid (TA). These incorporated\n1,2-dithiolane rings undergo photoinduced ring-opening polymerization,\nthus enabling the cross-linking of poly(lactic acid) with abundant\ndynamic disulfide bonds. The resultant CAN demonstrates excellent\ntransparency, effective UV-blocking capabilities below 320 nm, robust\ntensile strength (∼39 MPa), and superior dimensional stability\nat 80 °C, alongside attractive biocompatibility. Moreover, owing\nto the dynamic exchange and redox-responsiveness of disulfide bonds,\nthe material can be recycled by hot-pressing and a reduction–oxidation\nprocess while also being capable of controllably biodegrading at the\nend of its lifecycle. Furthermore, it exhibits reconfigurable shape\nmemory properties with fast recovery. This study elucidates a straightforward\napproach to fabricating multifunctional and sustainable polymer materials\nwith potential applications in diverse fields such as packaging, coating,\nand biomedicine.