Dehydrocoupling reaction catalyzed by palladium was used to synthesize aromatic-substituted poly(carbosiloxane)s having potentiality to be used as thermo-resistant insulating materials. Well-defined transmission holographic gratings with high diffraction efficiency were fabricated by the introduction of siloxane components: 1) to mesogenic compounds, 2) to bifunctional epoxides as cationically polymerizable monomers, which polymerize slower than radically polymerizable multi-functional acrylate.