Abstract: The present invention describes the use of copolymers with a composition gradient as sole stabilizer in emulsion free-radical polymerization. The copolymers of the invention are prepared via controlled free-radical polymerization and comprise at least one hydrophilic monomer such as acrylic acid and at least one hydrophobic monomer such as styrene.

Abstract: The present invention relates to a process for radical emulsion, miniemulsion or microemulsion polymerization employing at least one water-soluble alkoxyamine. This process makes it possible to prepare multiblock (co)polymers, in particular diblock and triblock (co)polymers.

Abstract: The method of the invention comprises: a) forming a hydrophilic polyurethane prepolymer with isocyanate end groups, by the polyaddition reaction of at least one polyol and at least one diisocyanate in the presence of at least one internal emulsifying agent; b) mixing the polyurethane prepolymer with a photochromic agent; c) adding water or a mixture of water and solvent, under agitation, to the mixture of the polyurethane prepolymer and the photochromic agent, to form an emulsion; and d) adding at least one chain extension agent to the emulsion and performing a chain extension reaction to give the final photochromic polyurethane latex. Application to the production of ophthalmic articles having photochromic properties.

Abstract: The invention concerns the use of at least one diazonium salt bearing an initiator function, for forming an undercoat obtained by grafting a graft derived from said diazonium salt and bearing an initiator function at the surface of a conductive or semiconductive material on said undercoat, and for forming on said undercoat a polymeric layer obtained by polymerization, in particular free radical polymerization, in situ of at least one monomer, initiated from said initiator function.

Abstract: The present invention relates to a process for radical emulsion, miniemulsion or microemulsion polymerization employing at least one water-soluble alkoxyamine. This process makes it possible to prepare multiblock (co)polymers, in particular diblock and triblock (co)polymers.

Abstract: This invention relates to a method for preparing a photochromic latex, photochromic thin films obtained therefrom, and articles coated with such thin films, in particular photochromic ophthalmic lenses.

Abstract: This invention relates to a method for preparing a photochromic latex, photochromic thin films obtained therefrom, and articles coated with such thin films, in particular photochromic ophthalmic lenses.

Abstract: Described are photochromic polyurethane coatings that meet commercially acceptable “cosmetic” standards for optical coatings. Also described are articles having such coatings. The coatings exhibit a Fischer microhardness of from 50 to 150 Newtons per mm and improved photochromic properties, i.e., the formation of darker activated colors and faster rates of photochromic activation and fade when irradiated with ultraviolet light.

Abstract: This invention relates to a method for preparing a photochromic latex, photochromic thin films obtained therefrom, and articles coated with such thin films, in particular photochromic ophthalmic lenses.

Abstract: A process for the emulsion polymerization in the presence of a stable free radical of at least one monomer which can be polymerized by the radical route, which emulsion comprises a liquid aqueous phase and a liquid organic phase, the aqueous phase comprising at least 50% by weight of water and the liquid organic phase comprising more than 50% by weight of monomer(s) to be polymerized. The invention results, by a rapid controlled polymerization process, in a latex of polymer particles, it being possible for the polymer to comprise acrylate and/or methacrylate blocks.