Patent ID: 8796359

Claim:
Polymer encapsulated solid particulate material that is 100 microns or less in size, said solid particulate material being encapsulated in a substantially uniform and continuous coating of polymer that has at least in part been formed under the control of a hydrophilic RAFT agent of general formula (4) and thereby has a reaction residue of the agent covalently bound thereto: where each X is independently a polymerised residue of a hydrophilic ethylenically unsaturated monomer selected from acrylic acid, methacrylic acid, hydroxyethyl methacrylate, hydroxypropyl methacrylate, acrylamide, methacrylamide, hydroxyethyl acrylate, N-methylacrylamide, dimethylaminoethyl methacrylate, itaconic acid, p-styrene carboxylic acids, p-styrene sulfonic acids, vinyl sulfonic acid, vinyl phosphonic acid, ethacrylic acid, alpha-chloroacrylic acid, crotonic acid, fumaric acid, citraconic acid, mesaconic acid and maleic acid, 2-(dimethyl amino) ethyl and propyl acrylates and methacrylates, and corresponding 3-(diethylamino) ethyl and propyl acrylates and methacrylates, n is an integer ranging from 1 to 100, R 1 is an organic group optionally substituted with one or more hydrophilic groups and Z is selected from optionally substituted alkoxy, optionally substituted aryloxy, optionally substituted alkyl, optionally substituted aryl, optionally substituted heterocyclyl, optionally substituted arylalkyl, optionally substituted alkylthio, optionally substituted arylalkylthio, dialkoxy- or diaryloxy-phosphinyl [—P(═O)OR 2 2 ], dialkyl- or diaryl-phosphinyl [—P(═O)R 2 2 ], optionally substituted acylamino, optionally substituted acylimino, optionally substituted amino, R 1 —(X) n —S— and a polymer chain, where R 1 , X and n are as defined above and R 2 is selected from the group consisting of optionally substituted C 1 -C 8 alkyl, optionally substituted C 2 -C 8 alkenyl, optionally substituted aryl, optionally substituted heterocyclyl, optionally substituted aralkyl, and optionally substituted alkaryl; wherein Z, X, n and R 1 are selected such that the RAFT agent is not capable of forming micelles in a hydrophilic liquid.