Additive Manufacturing of Hydrocarbon Elastomers via Simultaneous Chain Extension and Cross-linking of Hydrogenated Polybutadiene

This work describes the first example of a hydrogenated polybutadiene elastomer photopolymer that addresses the process constraints of vat photopolymerization (VP) additive manufacturing. A synthetic method, which involves simultaneous thiol-ene step growth chain extension and acrylate cross-linking, addresses traditional challenges associated with this leading 3D printing platform. This facile, one-pot strategy combines the processing advantages of low molecular weight oligomers with the tunable thermomechanical and mechanical performance of higher molecular weight polymeric networks directly during printing, without requiring a postprocessing step. The addition of photoinitiator to mixtures of liquid polybutadiene oligomer and miscible dithiols enabled selective photocuring under UV exposure to form high-strain, elastic parts in comparison to neat diacrylate systems. Photolithographic printing of these photopolymers enabled the fabrication of three-dimensional, hydrocarbon elastomer objects. Photorheology elucidated curing behavior as a function of composition and UV intensity, while optical imaging and SEM revealed quality and resolution.