Optical stereolithography of antifouling zwitterionic hydrogels†
This paper reports the rapid 3D printing of tough (toughness, UT, up to 141.6 kJ m−3), highly solvated (ϕwater ∼ 60 v/o), and antifouling hybrid hydrogels for potential uses in biomedical, smart materials, and sensor applications, using a zwitterionic photochemistry compatible with stereolithography (SLA). A Design of Experiments (DOE) framework was used for systematically investigating the multivariate photochemistry of SLA generally and, specifically, to determine an aqueous SLA system with an additional zwitterionic acrylate, which significantly increases the gelation rate, and the resilience of the resulting hybrid hydrogels relative to an equivalent non-ionic polyacrylamide hydrogel. Specifically, the resulting zwitterionic hybrid hydrogels (Z-gels) can be tuned over a large range of ultimate strains, ca. 0.5 < γult < 5.0, and elastic moduli, ca. 10 < E < 1000 kPa, while also demonstrating a high resilience under cyclic tensile loading. Importantly, unlike traditional chemistry, increasing the elastic modulus of the Z-gels does not necessarily reduce the ultimate strain. Moreover, the Z-gels can be rapidly printed using a desktop commercial SLA 3D printer, with relatively low photoirradiation dosages of visible light (135 to 675 mJ cm−2 per 50–100 μm layer). Compared with the counterpart polyacrylamide hydrogels, the Z-gels have greater antifouling properties and exhibit 58.2% less absorption of bovine serum albumin.