Norbornene Dicarboximide: A Green Alternative for Thiol-Norbornene Photopolymers.

Abstract

Carbic anhydride is an underappreciated starting material for 3D-printable, non-hydrogel photopolymers. Compared with other norbornene precursors, carbic anhydride is cheaper and reactive via aminolysis. As a result, the generalized and efficient functionalization with carbic anhydride can increase the utilization of thiol-norbornene photopolymers. Here, we report carbic anhydride's catalyst-free condensation with two commodity polymers: amine-functionalized polypropylene glycol and polydimethylsiloxane. The reaction completes in 1 h, produces water as the only byproduct, and does not require purification. It is therefore affordable, facile, and green. Mixing the product with thiol cross-linkers and the appropriate photoadditives produces photopolymers that are printable via Digital Light Processing. The photopolymers exhibit tunable tensile properties and a functional surface by varying the polymer backbone and thiol stoichiometry. Moreover, the photopolymers are 3D-printed into true-to-scale human aorta models and porous scaffolds with high resolution. The simple yet versatile platform will benefit additive manufacturing of soft materials and beyond.