We also explored the potential of combining different monomers to create a gradient in materials properties through FROMP. Following the work of Dean et al , three monomers with different densities were layered in a glass casting mold of 3 mm thickness, in order of density from highest to lowest (Figure ). Frontal polymerization was initiated in the middle layer, which contained monomer 3b that had a faster front speed and a lower front temperature. Subsequently, the adjacent monomers, featuring slower front speeds and higher front temperatures, began polymerizing from the interfaces with the central layer (Figure , Supplementary Video S8). This FROMP approach rapidly yielded materials with a spatial variation in Tg. The central region, with a Tg of 3 °C , was more flexible than the edges of the sample with a higher Tg and modulus at room temperature (Figure ).