The method of producing silane-modified copolymer

The present invention is substantially free of monomers M, the transition metal salt, the ligand of at least bidentate, atom transfer polymerization initiator, a first polymerization step of reacting by a radical atom transfer polymerization in a mixture containing a reducing agent and monomer M and silyl groups substituted monomer S, was added to the mixture resulting from the first polymerization step, the monomer S which is a silyl group substituted in a mixture resulting from the first polymerization step, radical atom transfer polymerization the method for producing a polymer mixture having a second polymerization step of reacting by. The resulting polymer mixtures are used as binders additives for sealant.