The present invention relates to a polymerizable composition comprising a)
at least one ethylenically unsaturated monomer and b1) at least one
multifunctional triazinyl based 2,2,6,6 tetramethylpiperidine-1-oxyl and a
free radical initiator or b2) at least one multifunctional triazinyl based
2,2,6,6 tetramethylpiperidine-1-oxyl-ether. Further aspects of the present
invention are a process for polymerizing ethylenically unsaturated
monomers, the (co)polymers obtainable by this process and the use of
multifunctional triazinyl based 2,2,6,6 tetramethylpiperidine-1-oxyls in
combination with a free radical initiator, or a multi-functional triazinyl
based 2,2,6,6 tetramethylpiperidine-1-oxyl-ethers for controlled
polymerization. In a particularly preferred embodiment at least one
additional heating step at a temperature from 140 to 280.degree. C. is
applied after polymerization is completed.
