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.

Stereoselective aliphatic polyesters were synthesized through the ring opening copolymerization of cyclic anhydrides and epoxides using a tin catalyst to yield Mn ~ 10-13 kDa macromolecules (Đ < 1.6). Isomerization...

Photopolymerization has been widely used to create cross-linked photoset materials that have found wide applicability, including in 3D printing. Among the many chemistries available for these processes, thiol-ene "click" chemistry provides a rapid and efficient route to produce such materials but also leaves residual alkene groups that may be further exploited for postpolymerization functionalization. In the case of aliphatic polycarbonates, these residual functional groups are demonstrated to be suitable for controlling the thermosolvation response by modifying hydrophobicity, enhancing radiodensity and biostability through incorporation of alkylthiol chains (i.e., hexadecanethiol) or halogenation using molecular iodine, and reducing biofouling using thiolterminated poly(ethylene glycol). To further enhance the potential for postfabrication modification, we further demonstrate the concept with off-stoichiometric stereolithographic 3D printing (OSS3DP), where we can selectively leave more than 30% additional alkenes on the scaffold surface for postpolymerization functionalization in a process that could have clinical utility across a range of medical devices and therapeutics.

There is an ever-growing push toward sustainability and green manufacturing in a wide array of industries, especially 3D printing, which is now recognized as a viable manufacturing method. The number of studies focusing on leveraging additive manufacturing of natural products continues to grow, with key areas of interest including exciting chemistries or modifications of natural products toward 3D printable materials, advancements in prototypes or products by changing feedstocks to green or bioderived alternatives, and the introduction of added functionalities or properties. This includes concepts such as processing natural or bioderived polymers into filament for extrusion-based 3D printing, the design of photopolymer resins and inks for vat photopolymerizations, jet printing, or direct ink writing processes, and the use of powders for selective laser sintering. The strategies employed to achieve materials suitable for 3D printing, the physical properties of the materials, and the resultant applications including strengths and limitations, will be explored in this review. Overall, the advancements in the field are leading to future opportunities in biomaterials and medical devices, electronics and batteries, and environmental remediation and water purification.

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.