Design and fabrication of a 3D stereolithography-printable hydrophilic silicone-based elastic composite biomimetic hydrogel

Additive manufacturing (AM) of silicone-based elastomer mimetic biomaterial is a daunting challenge due to the lack of miscibility of silicones to hydrogel precursors. Hydrogels have been widely investigated as a 3D printable material in diverse biomedical fields due to their hierarchical structure, resemblance to human tissues, and exceptional bioactivity. However, conventional hydrogels exhibit deficiencies in mechanical robustness, sluggish actuation kinetics, and instability in the shape-morphing behaviour. Hence, the incorporation of silicone into hydrogel remains attractive for the generation of strong elastic biomaterial. Yet, the conventionally high viscosity of silicone-based ink further restricts its fabrication with stereolithography (SLA) printing. Herein, we present a new class of hydrophilic silicone-based elastic composite hydrogel material with low pre-gel viscosity and rapid curing properties based on polar functionalized silicone and acrylamide for the fabrication of biomimetic structures with SLA printing. The printed material shows high transparency, silicone-dependent water uptake behaviour, and zero deviating printability on micron scale. Furthermore, the compression moduli of the printed materials lie in the range of 0.28 ± 0.04 MPa to 0.72 ± 0.05 MPa, which highly resembles the superficial and deep zones of articular cartilage. Moreover, the shear withstanding behaviour is prominent against the rheological test followed by the low damping properties implying its highly elastic nature. The oscillatory compression cycle confirms its non-deforming nature and almost zero permanent sets. To the best of our knowledge, this material could be ideal for the SLA printing of biomimetic structures.