Process for the preparation of graft copolymers by Reversible Addition Fragmentation Chain Transfer (RAFT) and Ring Opening Polymerisation (ROP)

A combined RAFT/ROP process for the preparation of a graft co-polymer having a backbone built-up from repeating units derived by polymerization of free-radically polymerizable monomers comprising vinylic monomers, and polyester side chains grafted to said backbone derived by ring-opening polymerisation of cyclic ester compounds; said process comprising reacting a mixture of (a) one or more vinylic monomers, optionally in combination with other monomers susceptible to free-radical polymerization, wherein at least one of said vinylic monomers comprises a (free) hydroxyl group; (b) a thiocarbonylthio compound as chain transfer agent; (c) one or more cyclic esters, which is/are susceptible to a ring-opening polymerization; and (d) a compound effective for initiating the ring-opening polymerization of the one or more cyclic esters; and reacting said mixture in an inert solvent at a temperature of more than 90°C under exclusion of oxygen to form the graft copolymer.