Using sequentially orthogonal photoreactions to tune mechanical properties of thiol-methacrylate networks

Light curable materials are extensively used in fields such as 3D printing, coatings, and photo-patterning; however, changing their mechanical properties after polymerization is rather difficult. Herein, a dual-wavelength responsive thiol-methacrylate system is introduced. Methacrylate functionalized anthracene moieties that undergo photodimerization upon illumination with 365 nm light are incorporated into a thiol-methacrylate system, which is cured at 450 nm beforehand. Sequentially orthogonal illumination at 365 nm, therefore, results in a pronounced change in mechanical properties. Specifically, a shift from 7.4 to 19.9 MPa in Young’s modulus was achieved through the addition of anthracene crosslinks, making this resin system a promising candidate for multi-material 3D printing.