The present disclosure relates to thermoplastic polymeric microspheres comprising a thermoplastic polymer shell surrounding a hollow core, in which the thermoplastic polymer shell comprises a homopolymer or copolymer of a monomer of Formula 1

##STR00001## wherein: each of A1 to A11 are independently selected from H and C1 to C4 alkyl, in which each C1-4 alkyl group can optionally be substituted with one or more substituents selected from halogen, hydroxy and C1-4 alkoxy; X is a linking group selected from —O—, —NR″—, —S—, —OC(O)—, —NR″C(O)—, —SC(O)—, —C(O)O—, —C(O)NR″—, and —C(O)S—; and R″ is H or C1-2 alkyl optionally substituted with one or more substituents selected from halogen and hydroxy.

A composite material according to the present invention includes a solid portion including inorganic particles and a resin. The composite material has a porous structure including a plurality of voids surrounded by the solid portion. In the composite material, a ratio of a smallest heat conductivity of heat conductivities λ.sub.x, λ.sub.y, and λ.sub.z respectively in x-axis, y-axis, and z-axis directions perpendicular to each other to a largest heat conductivity of the heat conductivities λ.sub.x, λ.sub.y, and λ.sub.z is 0.8 or more.

Heat-expandable microspheres including a thermoplastic resin shell and a thermally-vaporizable blowing agent encapsulated therein. The thermoplastic resin is produced by polymerizing a polymerizable component containing (A) a nitrile monomer including acrylonitrile and methacrylonitrile, (B) a carboxyl-group-containing monomer, and (C) a monomer copolymerizable with the nitrile monomer (A) and the carboxyl-group-containing monomer (B). Further, the amount of the acrylonitrile in the nitrile monomer (A) ranges from 0.1 to 9 wt % based on the nitrile monomer (A). Also disclosed are hollow particles manufactured by heating and expanding the heat-expandable microspheres; a composition containing a base compound and at least one particulate material selected from the heat-expandable microspheres and the hollow particles; and a formed product manufactured by molding or applying a coat of the composition.

Heat-expandable microspheres including a thermoplastic resin shell and a thermally-vaporizable blowing agent encapsulated therein. The thermoplastic resin is produced by polymerizing a polymerizable component containing (A) a nitrile monomer including acrylonitrile and methacrylonitrile, (B) a carboxyl-group-containing monomer, and (C) a monomer copolymerizable with the nitrile monomer (A) and the carboxyl-group-containing monomer (B). Further, the amount of the acrylonitrile in the nitrile monomer (A) ranges from 0.1 to 9 wt % based on the nitrile monomer (A). Also disclosed are hollow particles manufactured by heating and expanding the heat-expandable microspheres; a composition containing a base compound and at least one particulate material selected from the heat-expandable microspheres and the hollow particles; and a formed product manufactured by molding or applying a coat of the composition.

A method of forming a particle includes, in a disperse phase within an aqueous suspension, polymerizing a plurality of mer units of a hydrophilic monomer having a hydrophobic protection group, thereby forming a polymeric particle including a plurality of the hydrophobic protection groups. The method further includes converting the polymeric particle to a hydrophilic particle.

A method of forming a particle includes, in a disperse phase within an aqueous suspension, polymerizing a plurality of mer units of a hydrophilic monomer having a hydrophobic protection group, thereby forming a polymeric particle including a plurality of the hydrophobic protection groups. The method further includes converting the polymeric particle to a hydrophilic particle.

An emulsifier-free process for the preparation of water expandable polymer beads, including: a) providing an emulsifier-free starting composition comprising styrene, b) prepolymerizing the starting composition to obtain a prepolymer composition, c) mixing an aqueous blowing agent with the prepolymer composition at an elevated temperature to obtain an inverse emulsion of water droplets in the prepolymer composition, wherein the aqueous blowing agent comprises water and a water soluble initiator dissolved in the water and the water droplets comprise spheres of a styrene polymer, wherein the water soluble initiator partly decomposes due to the elevated temperature leading to the formation of the inverse emulsion of water droplets in the prepolymer composition, d) suspending the inverse emulsion in an aqueous medium to yield an aqueous suspension of suspended droplets and e) polymerizing monomers in the droplets of the suspension obtained by step d) to obtain the water expandable polymer beads.

An emulsifier-free process for the preparation of water expandable polymer beads, including: a) providing an emulsifier-free starting composition comprising styrene, b) prepolymerizing the starting composition to obtain a prepolymer composition, c) mixing an aqueous blowing agent with the prepolymer composition at an elevated temperature to obtain an inverse emulsion of water droplets in the prepolymer composition, wherein the aqueous blowing agent comprises water and a water soluble initiator dissolved in the water and the water droplets comprise spheres of a styrene polymer, wherein the water soluble initiator partly decomposes due to the elevated temperature leading to the formation of the inverse emulsion of water droplets in the prepolymer composition, d) suspending the inverse emulsion in an aqueous medium to yield an aqueous suspension of suspended droplets and e) polymerizing monomers in the droplets of the suspension obtained by step d) to obtain the water expandable polymer beads.

An expandable poly methyl methacrylate particle including a polymer, which is obtained by a process including polymerizing monomers including 100 parts by weight of an acrylic monomer and from 0.05 to 0.15 parts by weight of a polyfunctional monomer. The acrylic monomer includes 90% to 98% by weight of methyl methacrylate and 2% to 10% by weight of an C.sub.2-8 alkyl acrylate, relative to a total weight of the methyl methacrylate and the C.sub.2-8 alkyl acrylate.

This invention relates to monodisperse cross-linked polymer particles, comprising particles with a substantially smooth outer surface and an average diameter of less than 1 μm, wherein the particles are solid or porous, and wherein the coefficient of variation (CV) % of the particles, when measured by CPS disk centrifugation analysis, is less than 15%. These monodisperse cross-linked polymer particles may comprise magnetic material and are useful in various application. This invention also relates to monodisperse polymer particles for use as seed particles in the Ugelstad process.