POLYMERISATION REGULATION

A process for the production of low molecular weight polymers by free radica l polymerisation of one or more monomers in the presence of a chain transfer agent, characterized in that the chain transfer agent comprises one or more compounds of general formula (1), wherein R1 is a hydrogen atom, an alkyl group, or a group capab le of activating the vinylic carbon towards free radical addition; R2 represents an optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, or optionally substituted satured, unsatured or aromatic carbocyclic or heterocyclic ring; and Z represents an oxygen, sul- phur, phosphorus, or nitrogen atom bound to another atom or group of atoms i n order to satisfy its valency.