Two-Photon Absorption(TPA) microfabrication with copolymer containing TPA materials and epoxy moieties

Abstract

Three-dimensional microfabrication using two-photon absorption is attracting considerable attention owing to its various applications. Nevertheless, much of the work in two-photon three-dimensional (3-D) microfabrication has been restricted to the development of two-photon absorbing chromophore. And most researchers have not been concerned about the development of photo-crosslinkable resins for two-photon three-dimensional microfabrication. In this study, we suggested the copolymer system containing two-photon absorbing (TPA) materials and photo-crosslinkable moieties. This system has some advantages that are increasing of TPA materials and diversifying of resin monomer. In copolymer, first TPA materials receive energy from two-photon laser at 780nm and then emit fluorescence light. I-line photoacid generators (I-line PAGs) absorb this light and generate protons, which go to epoxy moiety so that cross-linking is occurred. Copolymers bearing triphenylamine derivatives as TPA chromophores and epoxy groups as photocrosslinkable monomers were synthesized. We diversified the TPA chromophores with small cross-section values and large cross-section values and compared these by changing quantities. Eventually, 3-D structures using large amounts of TPA materials with small cross-section values were better than using with large cross-section values. Moreover, we enhanced the shape of structures by replacing PAGs with photobase generators (PBGs) and changing to epoxy groups with aromatic benzene ring. Eventually, we have shown that not only 3-D structures can be manufactured by just increasing amounts of low efficient TPA materials but also resin properties are improved by modifying photo-crosslinkable moieties in the new copolymer system.