Poly(ϵ-caprolactone)-based shape memory polymers for biomedical applications: fundamentals, recent advances, and future perspectives
Poly(ϵ-caprolactone) (PCL)-based shape-memory materials have emerged as a versatile class of smart biomaterials that combine programmable mechanical behavior with biomedical functionality. In addition to biocompatibility, they exhibit adjustable thermal transitions, mechanical flexibility, and precisely controlled degradation characteristics. These materials exhibit reversible shape transformations driven by external stimuli. This facilitates their use in minimally invasive procedures and activation at the specific site within the body. This review presents a comprehensive overview of the physical principles governing shape-memory behavior in PCL systems, emphasizing structure–property relationships that control switching temperature, recovery stress, and long-term stability. Strategies to enhance performance through copolymerization, blending, and nanocomposite design are critically evaluated, alongside recent progress in additive manufacturing and 3D/4D printing that enables patient-specific architectures. Key applications include self-expanding stents, dynamic tissue-engineering scaffolds, microneedle systems, and smart drug-delivery implants, all biomedical uses of PCL-based SMPs. Furthermore, key issues like slow degradation, limited stimuli, mechanical challenges, and sterilization difficulties are identified and critically examined. Future research directions include multi-stimuli responsiveness, personalized implants, and sustainable polymer synthesis. Collectively, these innovations enhance the capabilities of PCL-based shape-memory systems, enabling them to become next-generation medical devices, advance regenerative therapies, and advance drug delivery technologies.