Adaptive and intelligent polyurethane shape-memory polymers enabling next-generation biomedical platforms

Polyurethane shape memory polymers (SMPUs) have emerged as a promising class of biomaterials due to their unique ability to recover their original shape upon exposure to external stimuli. Traditionally derived from petroleum-based sources, recent advancements have shifted focus toward utilizing renewable resources to develop sustainable SMPUs for biomedical applications. This review explores the synthesis, properties and applications of bio-based SMPUs, emphasizing their environmental advantages and functional benefits. Renewable sources such as plant-derived polyols, bio-based diisocyanates and chain extenders from lignocellulosic biomass serve as key precursors in synthesizing these polymers. These bio-derived SMPUs exhibit excellent biocompatibility, biodegradability and mechanical adaptability, making them suitable for applications in tissue engineering, drug delivery, wound healing and biomedical implants. Their shape memory properties, governed by thermally, light, or moisture-induced actuation, enable dynamic responses in medical devices and scaffolds. Moreover, the integration of bio-based components enhances sustainability while maintaining desirable characteristics such as elasticity, durability and non-toxicity. By discussing the history, chemistry and stimuli-responsive mechanisms of SMPUs, this review provides a comprehensive overview of their biomedical potential. Ultimately, bio-based SMPUs represent a greener alternative to conventional materials, aligning with global sustainability efforts while advancing biomedical innovation.