Method for preparing a polymer by nitroxyl-controlled polymerization, comprising the following steps: a) providing a mixture capable of radical polymerization, comprising or consisting of i) at least one monomer A1 polymerizable by radical polymerization, or a monomer mixture comprising or consisting of the at least one monomer A1 and at least one further monomer A2 capable of free-radical polymerization and different from the monomer A1, and ii) at least one initiator B selected from the group consisting of an alkoxyamine B1, which initiates the radical polymerization by cleavage into an alkyl and a nitroxyl radical and an initiator B2 comprising at least one radical starter and at least one nitroxyl radical, b) initiation of the radical polymerization and maintenance of the polymerization over a period of time that allows polymerization to a conversion of 10 to 100 %, c) addition of at least one reactive agent C after a conversion of the polymerization of between 10% and 100% in an amount which converts at least some or all of the alkoxyamine end groups of the polymer produced during the nitroxyl-controlled radical polymerization into a non-polymerizable group, and d) addition of at least one additive D to one or more of steps a) to c), which accelerates the nitroxyl-controlled polymerization reaction and/or the conveyance of the alkoxyamine end groups of the polymer into a non-polymerizable group. a) providing a mixture capable of radical polymerization, comprising or consisting of i) at least one monomer A1 polymerizable by radical polymerization, or a monomer mixture comprising or consisting of the at least one monomer A1 and at least one further monomer A2 capable of free-radical polymerization and different from the monomer A1, and ii) at least one initiator B selected from the group consisting of an alkoxyamine B1, which initiates the radical polymerization by cleavage into an alkyl and a nitroxyl radical and an initiator B2 comprising at least one radical starter and at least one nitroxyl radical, i) at least one monomer A1 polymerizable by radical polymerization, or a monomer mixture comprising or consisting of the at least one monomer A1 and at least one further monomer A2 capable of free-radical polymerization and different from the monomer A1, and ii) at least one initiator B selected from the group consisting of an alkoxyamine B1, which initiates the radical polymerization by cleavage into an alkyl and a nitroxyl radical and an initiator B2 comprising at least one radical starter and at least one nitroxyl radical, an alkoxyamine B1, which initiates the radical polymerization by cleavage into an alkyl and a nitroxyl radical and an initiator B2 comprising at least one radical starter and at least one nitroxyl radical, b) initiation of the radical polymerization and maintenance of the polymerization over a period of time that allows polymerization to a conversion of 10 to 100 %, c) addition of at least one reactive agent C after a conversion of the polymerization of between 10% and 100% in an amount which converts at least some or all of the alkoxyamine end groups of the polymer produced during the nitroxyl-controlled radical polymerization into a non-polymerizable group, and d) addition of at least one additive D to one or more of steps a) to c), which accelerates the nitroxyl-controlled polymerization reaction and/or the conveyance of the alkoxyamine end groups of the polymer into a non-polymerizable group.