Comparison of the Linear and Nonlinear Optical Properties of Poly(p-phenylenevinylene)/Sol−Gel Composites Derived from Tetramethoxysilane and Methyltrimethoxysilane

Poly( p -phenylenevinylene) (PPV) has been incorporated into sol−gel matrixes via its soluble precursor polymer, using tetramethoxysilane (TMOS) and methyltrimethoxysilane (MTMS) as the silane monomers. Linear absorption maximum (λ max ) and nonlinear refractive index n 2 of the PPV in the two composite systems were compared and studied. Compared to pristine PPV, a reduction was seen in λ max and | n 2 | of the composite films. This paper addresses chemical and processing effects directed at minimising this matrix-induced reduction in λ max and | n 2 |. Of the parameters studied, the nature of the silane monomer has the greatest influence on the λ max and | n 2 | values of the composites. The reduction of the λ max and | n 2 | values in the composite films was much greater when TMOS was the matrix host. There is a smaller decrease in both | n 2 | and λ max if acid catalysis is used during either the sol synthesis or during the thermal transformation process, but this effect is marginal for TMOS. A differential matrix effect on λ max and | n 2 | is also seen in the temperature required for the conversion to PPV within the respective matrixes.