Two-photon photoinitiated polymerization

The three-dimensional (3-D) spatial resolution of the two-photon absorption (2PA) process is being harnessed for 3-D microstructure fabrication and microlithography. In addition to the inherent spatial resolution of the two-photon excitation process, two-photon absorption can occur in certain materials at wavelengths well beyond that which monomers, polymers, and most organic substances absorb (one-photon), affording a greater depth of pcnetration and, in principle, creating little or no damage to the host. The near-IR two-photon induced free radical polymerization of (meth)acrylate monomers and the near-IR two-photon induced cationic polymerization of epoxide monomers using commercially available photoinitiator systems is described. We report the two-photon induced polymerization of a thiol-ene resin system utilizing near-IR radiation and a commercially available photoinitiator, isopropylthioxanthone (ITX). Polymerization depths of over 2 cm were achieved, demonstrating a new paradigm for deep curing of adhesives