Method for forming and 3d printing double network hydrogels using temperature-controlled projection stereolithography

Abstract

An apparatus and method for shaping double-network hydrogels into customized 3D structures. A one-pot prepolymer formulation containing photo-cross-linkable acrylamide and thermoreversible sol-gel κ-carrageenan with a suitable crosslinker, and photo-initiator/absorbers was used. The formulation was polymerized using a TOPS system with heating stage to photo-polymerize the primary acrylamide network into a 3D structure above the sol-gel transition of κ-carrageenan (80° C.). Cooling down then generates the secondary physical κ-carrageenan network to realize tough double-network hydrogel structures. Printed 3D structures had superior lateral (37 μm) and vertical (180 μm) resolutions and 3D design freedoms (internal voids) that exhibit ultimate stress and strain of 200 kPa and 2400% respectively under tension, and simultaneously exhibit high compression stress of 15 MPa with a strain of 95%, both with high recovery rates. The apparatus and method can be employed with other double-network hydrogels to make multifunctional soft devices for a range of applications.