Post-fabrication functionalization of 4D printed polycarbonate photopolymer scaffolds

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 thiol-terminated 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.