A One‐Stone‐Two‐Birds Strategy for Photothermal Shape Memory Polyurethane Utilizing Lignin as Monomer and Internal Photothermal Agent

Abstract

Photothermal‐triggering shape memory polyurethane allows for precise and controllable shape transformation under remote light stimulation, making it highly desirable for applications in intelligent devices. This study develops a sustainable and high‐performance lignin‐based polyurethane (LPU) using a one‐stone‐two‐birds strategy, wherein lignin serves as both a synthetic monomer and an internal photothermal agent. The incorporation of lignin significantly improved the mechanical properties of LPU, achieving a tensile strength of 42.1 MPa and an impressive elongation at break of 1558%. Additionally, the LPU exhibited exceptional photothermal heating capabilities due to the inherent intramolecular π–π conjugations and intermolecular π–π stacking effects of lignin, which facilitated the precise and contactless remote photoheating. Furthermore, the rigid structure of lignin and robust hydrogen bonding interactions provided LPU with excellent multi‐cycle shape memory performance, with shape fixation and shape recovery rates exceeding 93% after five cycles. Under near‐infrared irradiation, LPU demonstrated precise non‐contact heating and remote photothermal shape‐control capabilities. This research not only offers a sustainable and high‐value application for lignin but also advances the development of environmentally friendly intelligent shape memory polyurethane materials.