Abstract: The invention relates to novel microgel-containing essentially organic solvent nail varnishes. The microgels are particularly acrylic microgels. The invention also relates to the use of these microgels for modifying the physical properties of an essentially organic solvent nail varnish composition, and/or the properties of the film obtained during the application of said composition.

Abstract: The invention relates to a chain end functionalised polymer of formula: ##STR1## in which: the polymer chain (P) is a hydrophobic chain obtained by radical polymerisation of at least one monomer,R represents a hydrogen atom or a linear or branched hydrocarbon chain having 1 to 8 carbon atoms optionally substituted with at least one group selected from CO.sub.2, NH.sub.2, OH or a phenyl group, itself being optionally substituted,A and B, identical or different, each represent a single bond, a saturated or unsaturated linear or branched hydrocarbon chain having from 1 to 16 carbon atoms, it being possible for it to contain an amide bond or a peptide chain having 2 to 4 amino acids, particularly natural amino acids,the NH.sub.2 and/or COOH groups being free or salified.The invention also relates to the use of the above products as surfactants and more particularly as wetting agents, dispersing agents of solid particles and for preparing microdispersions of polymers, in particular microgels and microlatexes.

Abstract: The invention relates to a functionalised polymer of formula:(P)--S--X--F (1)in which:(P) is a hydrophobic polymer chain obtained by radical polymerisation of at least one monomer,S represents sulphur,X represents:a saturated or unsaturated linear or branched hydrocarbon chain having 1 to 6 carbon atoms and substituted with at least one COOH or NH.sub.2 group in the free or salified forma peptide chain constituted of 2 to 4 amino acids, particularly natural amino acids,F represents a COOH or NH.sub.2 group, in the free or salified form,with the exception of the .omega.-dicarboxylic macromonomers resulting from the radical polymerisation of a monomer in the presence of a chain transfer agent constituted of thiomalic acid.

Abstract: The invention relates to a process for the preparation of a stable microdispersion of particles comprised of acrylic polymers in an organic solvent used as reaction medium in the presence of a stabilizing agent comprised of a block copolymer, characterized in that said acrylic polymer is obtained by radical polymerization of at least one acrylic monomer in the presence of a block copolymer based on polymethyl methacrylate (PMMA) and polytert-butyl acrylate (PtBuA). It also relates to microdispersions which may be obtained by said process as well as to microgels produced from said microdispersions and compositions, particularly cosmetic compositions such as nail varnish.

Abstract: Block copolymers denoted by AB from acrylic or methacrylic acid, the corresponding blocks being denoted by A, and from alkyl acrylate or methacrylate with the alkyl chain being C.sub.1 -C.sub.10, the corresponding blocks being denoted by B. Said copolymer blocks are used as wetting and/or dispersing agents for solid particles in an essentially organic medium consisting of a solvent or a mixture of solvents solubilizing the block B.The invention also concerns solid particle dispersions using the above-defined block copolymers.It also concerns compositions, in particular cosmetic compositions, containing said dispersions.