Porous Materials Based on Poly(methylvinylsiloxane) Cross-Linked with 1,3,5,7-Tetramethylcyclotetrasiloxane in High Internal Phase Emulsion as Precursors to Si-C-O and Si-C-O/Pd Ceramics

Abstract

Polysiloxane networks were prepared by hydrosilylation of poly(methylvinylsiloxane) (V3 polymer) with 1,3,5,7-tetramethylcyclotetrasiloxane (D4H) at various Si-Vinyl: Si-H groups molar ratios in water-in-oil high internal phase emulsion (HIPE). Curing the emulsions followed by removal of water led to foamed cross-linked polysiloxane systems differing in the cross-linking degrees, as well as residual Si-H and Si-Vinyl group concentrations. Treatment of thus obtained materials in Pd(OAc)2 solution in tetrahydrofuran resulted in the formation of porous palladium/polymer nanocomposites with different Pd contents (1.09–1.70 wt %). Conducted investigations showed that pyrolysis of the studied materials at 1000 °C in argon atmosphere leads to porous Si-C-O and Si-C-O/Pd ceramics containing amorphous carbon and graphitic phases. Thermogravimetric (TG) analysis of the starting cross-linked polymer materials and those containing Pd nanoparticles revealed that the presence of palladium deteriorates thermal stability and decreases ceramic yields of preceramic networks. The extent of this effect depends on polymer cross-linking density in the system.

The Preparation of a novel moisture-curing silicone conformal coating

“…Traditional techniques used for the synthesis of α, ω-dihydroxy polydimethylsiloxanes include hydrolytic condensation reactions of chlorosilanes [17], ring-opening polymerization of cyclosiloxanes [18,19], and the sol-gel method utilizing alkoxysilanes [20]. This study introduces a novel approach for the synthesis of high molecular weight hydroxyl-terminated polysiloxane (PDMS-OH) utilizing low molecular weight hydroxyl silicone oil as a precursor.…”