Organic–Inorganic Hybrid Thermal Insulation Materials Prepared via Hydrosilylation of Polysilsesquioxane Having Hydrosilyl Groups and Triallylisocyanurate

In the quest for efficient thermal insulation materials, enhancing the thermal insulation property of polysilsesquioxanes (PSQs) by introducing crosslinkers is a promising strategy. In this study, organic–inorganic hybrid films containing isocyanurate rings in the PSQ network were prepared by the hydrosilylation reaction of hydrodimethylsilylated oligomethylsilsesquioxane (MSQ-SiH) and triallylisocyanurate (TAIC) as a crosslinker in the presence of Karstedt's catalyst. The formation of the MSQ/TAIC hybrid films was confirmed by attenuated total reflection Fourier transform infrared spectroscopy and 13C and 29Si solid-state nuclear magnetic resonance spectroscopy. The obtained MSQ/TAIC hybrid films were colorless, transparent, and stiff, regardless of the amount of TAIC in the PSQ network. The thermal diffusivity of the MSQ/TAIC hybrid films (1.01 × 10–7–1.14 × 10–7 m2/s) was lower than that of an MSQ film (1.44 × 10–7 m2/s) prepared by the oxidative homocoupling reaction of MSQ-SiH and a PSQ/tris(3-triethoxysilylpropyl)isocyanurate (TESIC) film (1.25 × 10–7 m2/s) prepared by the polycondensation reaction of ethoxy- and hydroxy-containing polymethylsilsesquioxane and tris(3-triethoxysilylpropyl)isocyanurate (TESIC). A positron annihilation lifetime analysis indicated that the decrease in thermal diffusivity was due to the nature of the TAIC structure rather than to the formation of intramolecular void spaces. Thermogravimetric measurements revealed that the MSQ/TAIC hybrid films were thermally less stable than the MSQ film but more stable than the PSQ/TESIC film and previously reported TAIC-containing polymer films, which demonstrates that MSQ-SiH is a suitable oligomer for the preparation of hybrid materials with high thermal stability.