Abstract: Powdery silica composite particles obtained by a surface treatment step of adding acid or alkali to a reactant solution comprising: core silica particles of 5 to 200 nm in average particle size; alkoxysilane; a phosphonium salt ionic liquid represented by general formula (1); wherein R1, R2, and R3 respectively represent a linear or branched alkyl group having 1 to 5 carbon atoms, R4 represents a linear or branched alkyl group having 1 to 5 carbon atoms, n represents an integer of 1 to 8, and X represents an anionic group; and a reaction solvent such that the alkoxysilane is hydrolyzed, thereby surface-treating the core silica particles.

Abstract: It is intended to provide highly dispersible, powdery silica composite particles comprising a phosphonium salt ionic liquid immobilized in the surface and comprising the ionic liquid at a high content. It is also intended to provide an industrially advantageous process for producing the powdery silica composite particles at high yields. The present invention provides powdery silica composite particles obtained by a surface treatment step of adding acid or alkali to a reactant solution comprising: core silica particles of 5 to 200 nm in average particle size; alkoxysilane; a phosphonium salt ionic liquid represented by the following general formula (1); and a reaction solvent such that the alkoxysilane is hydrolyzed, thereby surface-treating the core silica particles.

Abstract: A material enabling uniformly dispersing an ionic liquid or a phosphonium salt in various solvents or resin materials is provided. The material is powdery particles of a three-dimensionally crosslinked clathrate obtained by a process including a first-order polymerization step in which a fluoroalkanoyl peroxide compound, a monofunctional monomer, and a polyfunctional monomer having an olefinic double bond and an isocyanate group are reacted to one another to obtain a fluoroalkyl-containing cooligomer and a crosslinking step including the substeps of mixing the fluoroalkyl-containing cooligomer and an ionic liquid or a phosphonium salt and causing the cooligomer to react with itself at the isocyanate groups thereof in the presence of the ionic liquid or the phosphonium salt to obtain powdery three-dimensionally crosslinked clathrate particles.