Sustainable 4D printing of bio-based shape memory polymer composites derived from isoborneol–thioctic acid with photothermal actuation

The evolution of 4D printing for adaptive soft robotics is currently hindered by a reliance on petroleum-based feedstocks and the operational constraints of direct thermal actuation. Addressing these critical sustainability and functionality gaps, we engineer a high-performance shape memory polymer (SMP) system derived entirely from renewable resources, specifically isoborneol and thioctic acid. By strategically leveraging the rigid bicyclic skeleton of isoborneol, we successfully overcome the inherent trade-off between mechanical rigidity and flexibility typical of bio-polymers. This unique molecular design yields unprecedented mechanical properties for a fully bio-based material, achieving a tensile strength of 10.6 MPa alongside exceptional shape fixity (99%) and recovery (87%). Unlike many bio-based alternatives, this system is specifically tailored for high-resolution Liquid Crystal Display (LCD) 4D printing, ensuring precise fabrication of complex geometries without compromising material integrity. Moving beyond limited direct heating, we pioneer a bio-based SMP composite reinforced with carbon nanotubes (CNTs). This integration enables efficient, remote actuation via near-infrared (NIR) irradiation. This breakthrough facilitates wireless control capabilities while maintaining the composite's excellent printability and mechanical performance. Collectively, these advancements establish a sustainable, versatile, and wirelessly controllable platform, paving the way for the next generation of intelligent, eco-friendly soft robotic systems.