The advent of smart or functional 3D printing (3DP) materials (“four-dimensional (4D) materials”) represents one important development toward addressing current limitations in medicine, aerospace, and other fields. Here, we report on how the ring opening copolymerization (ROCOP) of readily available and well-known anhydrides and epoxides may be used to produce a library of polyesters that are capable of being leveraged in thiol-ene photopolymer resins for processing by stereolithography or digital light processing. These polyesters display a 4D behavior (shape memory), can be processed into complex 3D structures readily, and display robust mechanical properties including elastic moduli greater than 600 MPa (with corresponding strains at break of 52.5%). These materials, with their advanced properties and robust mechanical behaviors, represent a significant advancement in the quest for 4D printing materials.

Photopolymers are one of the fastest growing 3D printing material classes, despite the lack of diversity in performance or composition. A simple addition of graphite nanopowder is explored for tailoring aliphatic polycarbonate performance and enhancing advanced material properties, targeting the mechanical performance of the norbornene-containing poly(norbornene trimethyl carbonate) using poly(trimethyl propane allyl ether carbonate) for thermoset formation using thiol-ene photochemistry. A 30 wt% graphite-composite photopolymer ink displays shear thinning behavior suitable for pneumatic direct ink write (DIW) printing, along with enhanced elastic modulus (15-542 MPa) and an increase in ultimate strength (2-22 MPa for the composite ink) without significant variation in the glass transition temperature. The composites are further demonstrated as 4D materials including shape memory, conductivity, and recyclability, with this work serving as a guide for designing DIW inks from photopolymer resins.