4D Photopolymers Derived From Ring-Opening Copolymerization of Cyclic Anhydrides and Limonene Oxide

Natural product-derived materials are a growing source of interest for bioderived polymers or materials with improved sustainability profiles, but only recently have such materials truly started to be recognized as potentially viable alternatives to petrochemically derived commodity polymers. The terpene derivative limonene oxide offers a route toward degradable polyester copolymers with the added benefit of other potential functional groups, such as residual alkenes, used here for further exploration of these materials in vat photopolymerization 3D/4D printing modalities. Here, we demonstrate limonene oxide for organobase/thiourea (co)catalyzed ring-opening copolymerization of photopolymer precursors used in free-radical and thiol–ene cross-linking for 4D printing using digital light processing (DLP). The role of different alternating units, derived from four cyclic anhydrides, is explored to determine the relationship with thermomechanical, shape memory, gelation, and gravimetric properties. Ultimately, these bioderived polyester resins result in tunable physical properties with tailorable degradation profiles while maintaining bioderived content ranging from 25% to 65% of the total mass of the resins and thermoset parts. This demonstrates the potential of such an approach for pushing 3D/4D printing toward a greener pathway without sacrificing the physical properties necessary while adding advanced functional behaviors and considerations for end-of-life usage.