POLYMER PARTICLES OF UP TO 100 NANOMETRES DIAMETER COMPRISING CORE OF FREE RADICAL ADDITION POLYMER SURROUNDED BY A SHEATH OF POLYOXYALKYLENE CHAINS, SOME OF WHICH ARE COVALENTLY BOUND TO THE CORE

摘要

Very small (100 nanometres maximum) non-ionically-stabilised core-sheath addition polymer particles, wherein the core is addition polymer and the sheath polyoxyalkylene chains, at least a portion of which chains are bonded to the core, there being present on each core sufficient chains such that the mass ratio of core to sheath is from 98:2 to 60:40. The particles are prepared by polymerisation in aqueous media initiated at under 40oC. In a preferred embodiment, a seed-feed process is used. The dispersions exhibit excellent rheological characteristics and are useful, for example, as film-formers in coating compositions.