Photobase Initiated Network Formation for Two-Photon Polymerization

Additive manufacturing of high resolution, responsive soft materials is highly desired for applications including robotics, cellular scaffolds, and responsive metamatierals. Two-photon polymerization (2PP) is a form of direct laser writing whereby a pulsed, femtosecond laser is tightly focused onto three dimensional volume element (voxel) within a droplet of resin to locally initiate polymerization. The pulsed beam is translated over a designated path to polymerize customized, three-dimensional structures with feature lengths well below a micron. We demonstrate that a photobase generator within a mixture of multifunctional thiol and multifunctional acrylate monomers can lead to rapid formation of a molecular network. Spectroscopic analysis establishes how the degree of chemical conversion depends on laser dose. Our results open up new pathways to develop 2PP resins for printing high-resolution microstructures with improved conversion, mechanical properties, and reduced shrinkage.