Recyclable Lignin‐Based Thermadapt Shape Memory Polymers With Near‐Infrared Light Response

ABSTRACT Covalent adaptable networks (CANs) have been designed to address the recycling challenges associated with thermosets, while preserving their mechanical properties. However, producing biobased CANs with intelligent response capabilities remains challenging. We report the preparation of lignin‐polypentadecalactone‐based CANs with a high biomass content (86.2–96.4 wt%). In lignin‐PPDL CANs, acetoacetate‐modified lignin serves dual roles as the hard segment and crosslinker, while the polypentadecalactone (PPDL) soft segment exhibits a semi‐crystalline nature. Crosslinking between the soft PPDL and hard lignin segments is achieved via vinylogous urethane chemistry, resulting in CANs with markedly enhanced mechanical properties and recyclability. When applied to shape memory systems, the semi‐crystalline polymer domains act as reversible molecular switches, while dynamic bond exchange enables topological rearrangement, allowing reconfiguration of the permanent shape, characteristic of thermadapt shape memory polymers. Leveraging the photothermal conversion capability of lignin, we successfully developed near‐infrared (NIR) light‐responsive shape memory CANs. These innovative materials hold promising prospects for applications in intelligent materials, given their unique combination of mechanical strength, shape memory capabilities, and responsiveness to NIR light. Furthermore, the approach of tailoring the new material based on the specific properties of the raw material in this study offers a novel avenue for designing high‐performance multifunctional CANs.