Patent ID: 7572869

Claim:
A process for preparing an oligomer, a cooligomer, a polymer or a copolymer (block or random) by free radical polymerization of at least one ethylenically unsaturated monomer or oligomer, which comprises (co)polymerizing the at least one monomer or oligomer in the presence of an initiator compound of formula Ia, IIa or IIIa under reaction conditions capable of effecting scission of the O—C bond to form two free radicals, the radical .X being capable of initiating polymerization, where the compounds of formula Ia, IIa or IIIa are X is CH 3 CH-phenyl; n is 1; Y and Y′ are independently C 1 -C 12 alkyl, C 3 -C 12 alkenyl, phenyl or benzyl; or Y and Y′ together form one of the bivalent groups —C(R 1 )(R 2 )—CH(R 3 )—, —CH(R 1 )—CH 2 —C(R 2 )(R 3 )—, —CH(R 2 )—CH 2 —C(R 1 )(R 3 )— or —CH 2 —C(R 1 )(R 2 )—CH(R 3 )—, wherein R 1 is hydrogen, C 1 -C 12 alkyl, COO—(C 1 -C 12 )alkyl or CH 2 OR 4 ; R 2 and R 3 are independently hydrogen, methyl, ethyl, or COO—(C 1 -C 12 )alkyl; and R 4 is hydrogen, C 1 -C 12 alkyl, benzyl, or a monovalent acyl residue derived from an aliphatic, cycloaliphatic or aromatic monocarboxylic acid having up to 12 carbon atoms, with the proviso that compound A is excluded