SBIR Phase II: Ultra-softening polymers from engineered thiol-based resins for additive manufacturing

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The broader impact/commercial potential of this Small Business Innovation Research (SBIR) Phase II project is making tough, 3D printed parts that can be directly manufactured through additive processes commercially available. Additive manufacturing has potential to revolutionize the way parts are produced by streamlining product design, production, and validation, which allows for low production costs and accelerated lead times. The penetration of additive technology into industrial processes has been greatly slowed by the current inability to 3D print parts of any stiffness with materials properties on par with traditionally manufactured parts. Particularly, 3D printed materials tend to tear or fracture more readily between successive printed layers. At Adaptive 3D Technologies, we have developed resins that produce tough, robust parts that are tougher than many current 3D printed products in the x, y and z planes by achieving covalent crosslinking across printed layers. These materials and processing techniques will help drive additive manufacturing into large volume, yet customizable, market sectors to increase efficiency and productivity across industries. The printed parts resulting from our printable materials will further U.S. manufacturing by lowering production costs, increasing product performance and reshoring advanced manufacturing. This project is focused on understanding interface chemistry and adhesion phenomena in a special class of low-viscosity, thiol-ene resins to produce a range of mechanically tough materials that are 3D printable via stereolithography (SLA). A significant problem with current SLA approaches is that successive printed layers do not adhere sufficiently together, leading to large reductions in toughness as measured by the stress-strain response in soft, viscoelastic and stiff materials. Our Phase II research explores the tradeoffs between molecular architecture, reactivity, resin viscosity, and key printing parameters to develop improved materials to enable tougher printed parts than industry standards along multiple axes of deformation at similar printing speeds and feature sizes well below 100 microns. We have developed a portfolio of 3D printable materials with room temperature Young's moduli near 2 MPa, 20 MPa, 200 MPa or 2 GPa. Soft and viscoelastic materials have strain capacities well above 100% in all print directions, including when measured perpendicular to print layer interfaces. We expect to further our polymers' thermomechanical properties through the proposed Phase II SBIR effort by incorporating proper additives into our systems to control color, shelf life, aesthetics, mechanical properties and compatibility with various jetting techniques.