Abstract: The invention provides a method of preparing an aqueous dispersion of vesiculated polymer particles, the method comprising: preparing a dispersion of polymerisable particles within a continuous aqueous phase, the polymerisable particles having a structure that is defined by an outer organic phase that comprises one or more ethylenically unsaturated monomers and surrounds an inner aqueous phase, said inner aqueous phase defining a single void within the polymerisable particle, wherein a RAFT agent functions as a stabiliser for the outer organic phase within the continuous aqueous phase, and wherein a RAFT agent functions as a stabiliser for the inner aqueous phase within the outer organic phase; and polymerising the one or more ethylenically unsaturated monomers under the control of a RAFT agent functioning as said stabiliser to form the aqueous dispersion of vesiculated polymer particles.

Abstract: This invention relates to a process for preparing an aqueous dispersion of water insoluble polymer particles comprising: a) preparing by polymerisation an aqueous dispersion of water insoluble particles of a heteropolymer including monomeric units of a reactive amphiphile having a cloud point and monomeric units of a hydrophilic monomer, said polymerisation being conducted in the presence of a stabilising agent and the reactive amphiphile and at a temperature above the cloud point of said amphiphile, and b) cooling said aqueous dispersion to a temperature below the cloud point of the reactive amphiphile such that the viscosity of the aqueous dispersion increases. The invention also relates to aqueous dispersions of water insoluble heteropolymer particles which incorporate units of reactive amphiphile.