Sol-gel polymerization and the fabrication of second-order nonlinear optical sol-gel films

econd order nonlinear optical materials were fabricated by sol-gel processing using organic, NLO chromophore containing, organosilanes such as N-((triethoxysilyl)propyl) -2,4-dinitrophenylamine (TDP) and 3-(4-formyl phenoxy)propyltrimethoxy silane (FPT). The organic chromophores survived the sol-gel process and could be incorporated directly into the silica network via silicon-carbon bonds. The morphology of the film depended upon the water/silane ratio, the type of catalyst used, the type of solvent used, and the overall concentration of the sol. The Second Harmonic Generation coefficients, (d;The magnitude of the SHG power generated by the films was found to depend on the type of substrate, the poling temperature and voltage, and the extent of reaction. The thermal stability of the SHG signal was found to depend on the silicate structure. ;The reaction kinetics of the sol-gel process of di-, tri-, and tetrafunctional silanes was also studied. The kinetic study of TEOS and TMOS showed that both esterification and alcohol condensation reactions are important in sol-gel polymerization even though the hydrolysis and water producing condensation reactions dominate the process.;The rate of the hydrolysis reactions of di- or trifunctional organomodified silanes was shown to depend on the catalyst concentration, and was affected by steric hindrance and inductive stabilization of the transition state. The hydrolysis rate was found to decrease in the order DMDEOS...