Polythiourethanes for Advanced Applications

Photopolymer systems, such as those based on acrylate or thiol-ene chemistries, see widespread use due to the utility and convenience in the ability to rapidly cure the resin via light exposure. These materials are used in fields such as lithography, medicine, adhesives, and printing. However, these materials have drawbacks that limit their expansion into certain areas. Both acrylic and thiol-ene photopolymers tend to have poor mechanical strength and inadequate thermal performance for use in additive manufacturing and softening bioelectronics. Thiol-isocyanate resins have potential to demonstrate the mechanical and thermal properties needed in these fields, but an effective photo-curing system has been elusive. This work presents the design, synthesis, and effectiveness of quaternary ammonium salts as photo-catalysts for thiol-isocyanate resins. Photopolymer resins are designed which increase the toughness of photopolymer 3D printing systems by an order of magnitude, and the heat deflection temperature by over two times. This brings performance in-line with commonly used engineering polymers. Resins are also designed which exhibit improved softening and durability as substrates for bioelectronics devices. Functional intracortical probes are shown to minimize micromotion induced stresses and successfully record neuronal activity. Further applications in fused filament fabrication and dielectric elastomer actuators are explored and validated, showing that thiol-isocyanate photopolymer resins might have wide-ranging use in multiple industries.