RAFT agent of formula I) I) Z-C(=S)-S-R-S-P where Z is a Z group typical of RAFT polymerization and is selected from a) phenyl, b) phenoxy, c) alkoxy having 1 to 30 carbon atoms, d) alkyl having 1 to 30 carbon atoms, e) S-alkyl having 1 to 30 carbon atoms, where the attachment to the -C(=S)-S-R-S-P radical of the RAFT agent is via the sulfur atom, f) heterocyclic groups, g) alkyl(phenyl)amino having 1 to 30 carbon atoms, where the attachment to the -C(=S)-S-R-S-P radical of the RAFT agent is via the nitrogen atom, h) dialkylamino having 1 to 30 carbon atoms in each alkyl chain, where, in all the groups, the attachment to the -C(=S)-S-R-S-P radical of the RAFT agent is via the nitrogen atom and where the two alkyl groups may be the same or different, and where R is an R group typical of RAFT polymerization and is selected from a) cyanoisopropyl, b) 2-phenylpropan-2-yl, c) cyano(phenyl)methyl, d) 1-ethoxy-2-methyl-1-oxopropan-2-yl, e) 2,4,4-trimethylpentan-2-yl, f) 1-cyanoethyl, g) 1-phenylethyl, h) tert-butyl, i) cyanomethyl, j) benzyl, k) polymethacrylates which, as a result of the synthesis, may have a carbamate group or a dithiocarbamate group, where the attachment to the Z-C(=S)-S- radical of the RAFT agent is via the secondary carbon atom of the first methacrylate unit of the polymethacrylate group, and where C is a carbon atom, and where S is a sulfur atom, and where P is a protecting group selected from the group consisting of S(=O) 2 -R 1 with R 1 = alkyl, benzyl or phenyl and S-C (=S) -N-R 2 R 3 with R 2 and R 3 = alkyl, benzyl or phenyl and C(=O)-R 4 with R 4 = alkyl and N-R 5 R 6 with R 5 = hydrogen atom, alkyl, benzyl or phenyl and R 6 = alkyl, benzyl or phenyl and SiR 7 R 8 R 9 with R 7, R 8 and R 9 = alkyl or benzyl and S(=O) 2 -OM with M = Na, K or H. where Z is a Z group typical of RAFT polymerization and is selected from a) phenyl, b) phenoxy, c) alkoxy having 1 to 30 carbon atoms, d) alkyl having 1 to 30 carbon atoms, e) S-alkyl having 1 to 30 carbon atoms, where the attachment to the -C(=S)-S-R-S-P radical of the RAFT agent is via the sulfur atom, f) heterocyclic groups, g) alkyl(phenyl)amino having 1 to 30 carbon atoms, where the attachment to the -C(=S)-S-R-S-P radical of the RAFT agent is via the nitrogen atom, h) dialkylamino having 1 to 30 carbon atoms in each alkyl chain, where, in all the groups, the attachment to the -C(=S)-S-R-S-P radical of the RAFT agent is via the nitrogen atom and where the two alkyl groups may be the same or different, and where R is an R group typical of RAFT polymerization and is selected from a) cyanoisopropyl, b) 2-phenylpropan-2-yl, c) cyano(phenyl)methyl, d) 1-ethoxy-2-methyl-1-oxopropan-2-yl, e) 2,4,4-trimethylpentan-2-yl, f) 1-cyanoethyl, g) 1-phenylethyl, h) tert-butyl, i) cyanomethyl, j) benzyl, k) polymethacrylates which, as a result of the synthesis, may have a carbamate group or a dithiocarbamate group, where the attachment to the Z-C(=S)-S- radical of the RAFT agent is via the secondary carbon atom of the first methacrylate unit of the polymethacrylate group, and where C is a carbon atom, and where S is a sulfur atom, and where P is a protecting group selected from the group consisting of S(=O) 2 -R 1 with R 1 = alkyl, benzyl or phenyl and S-C (=S) -N-R 2 R 3 with R 2 and R 3 = alkyl, benzyl or phenyl and C(=O)-R 4 with R 4 = alkyl and N-R 5 R 6 with R 5 = hydrogen atom, alkyl, benzyl or phenyl and R 6 = alkyl, benzyl or phenyl and SiR 7 R 8 R 9 with R 7, R 8 and R 9 = alkyl or benzyl and S(=O) 2 -OM with M = Na, K or H.