Patent ID: 7253232

Claim:
A composition comprising A) a thermoplastic polymer and B1) a triblock-copolymer of the formula B-C-B; or B2) a graft copolymer wherein a polymer block B is grafted onto a polymer C to form a comb copolymer of idealized formula C-B(n) wherein n is greater than 2; wherein the polymer block B is compatible to the thermoplastic polymer A); and the polymer block C is a polysiloxane which has a glass transition temperature of at least 20° K. below the glass transition temperature of the thermoplastic polymer A); and the average molecular weight M w of the triblock-copolymer B1) or grafted comb copolymer B2) is below 50 000, and wherein the triblock copolymer or the graft copolymer is prepared via controlled free radical polymerization comprising the steps a) reacting a polysiloxane, in the presence of a functional alkoxyamine of formula (I) under hydrosylilation conditions and b) reacting the resulting alkoxyamine modified polysiloxane with an ethylenically unsaturated monomer at a temperature between 60 and 160° C., wherein X represents a group having at least one carbon atom and is such that the free radical is capable of initiating polymerization of ethylenically unsaturated monomers, n is a number from 0-18; R and R′ are independently tertiary bound C 4 -C 28 alkyl groups which are unsubstituted or substitituted by one or more electron withdrawing groups or by phenyl; or R and R′ together form a 5 or 6 membered heterocyclic ring which is substituted at least by 4 C 1 -C 4 alkyl groups and which may be interrupted by a further nitrogen or oxygen atom.