Polysiloxane block copolymers

1. A polysiloxane block copolymer of the formula A[LB(S)Q] m where A is a polysiloxane block, L is a divalent organic radical which links the units A and B, B is a polymer block composed of radically polymerized monomers M, S is a sulfur atom and Q is a monovalent organic radical and m is an integer from 1 to 50.

2. The polysiloxane block copolymer as claimed in claim 1 , wherein A is a branched or unbranched, substituted or unsubstituted polysiloxane radical which is described by formula (I)

where

b is a number from 0 to 10,

a is a number from 1 to 500,

R f are identical or different radicals R 1 or the linking radical L, with the proviso that at least one radical R f is a radical L and at most 50 radicals R f are radicals L, and

R 1 are alkyl radicals having 1 to 18 carbon atoms, where the radicals R 1 may be substituted or unsubstituted.

3. The polysiloxane block copolymer as claimed in claim 1 , wherein L is a branched or unbranched, substituted or unsubstituted hydrocarbon radical having 1 to 60 carbon atoms which has at least one unit —C(O)—.

4. The polysiloxane block copolymer as claimed in claim 1 , wherein B is a poly(meth)acrylate unit with a number-average molecular weight of from 1000 g/mol to 200 000 g/mol.

5. The polysiloxane block copolymer as claimed in claim 1 , wherein Q is an alkyl radical, an alcohol radical or an acid radical, preferably having 1 to 20 carbon atoms.

6. The polysiloxane block copolymer as claimed in claim 1 , wherein the block copolymer has a number-average molecular weight of from 5000 g/mol to 1 000 000 g/mol.

7. The polysiloxane block copolymer as claimed in claim 1 , wherein the block copolymer has less than 5 mass-ppm of terminal halogens.

8. The polysiloxane block copolymer as claimed in claim 2 ,

wherein:

L is a branched or unbranched, substituted or unsubstituted hydrocarbon radical having 1 to 60 carbon atoms which has at least one unit —C(O)—;

B is a poly(meth)acrylate unit with a number-average molecular weight of from 1000 g/mol to 200 000 g/mol;

Q is an alkyl radical, an alcohol radical or an acid radical, preferably having 1 to 20 carbon atoms;

the block copolymer has a number-average molecular weight of from 5000 g/mol to 1 000 000 g/mol; and

the block copolymer has less than 5 mass-ppm of terminal halogens.

9. A method of producing polysiloxane block copolymers as claimed in claim 1 , which comprises the steps

A) reaction of an atom transfer radical initiator, which is a polysiloxane macroinitiator of the formula A[LX] m , which has at least one organically bonded halogen atom X, where A is a polysiloxane block, L is a divalent organic radical and m is an integer from 1 to 50, with radically polymerizable monomers M in the presence of a catalyst having transition metal in a polymerization step and

B) addition of a compound Q-SH, where Q is a monovalent organic radical, to the polymerization mixture of step A).

10. The method as claimed in claim 9 , wherein substituted or unsubstituted (meth)acrylic acid or derivatives thereof are used as radically polymerizable monomers.

11. The method as claimed in claim 9 , wherein thioglycolacetic acid, mercaptopropionic acid, mercaptoethanol, mercaptopropanol, mercaptobutanol, mercaptohexanol, octyl thioglycolate, methyl mercaptan, ethyl mercaptan, butyl mercaptan, dodecyl mercaptan, isooctyl mercaptan or tert-dodecyl mercaptan is used as compound Q-SH.

12. A composition comprising at least one polysiloxane block copolymer as claimed in claim 1 .

13. The composition as claimed in claim 12 , wherein the composition is a cosmetic composition or a personal care composition.

14. A method of treating and/or conditioning hair which comprises administering the composition as claimed in claim 12 to the hair of a person in need thereof.