Abstract: Process for producing SiOC-bonded, linear polydialkylsiloxane-polyoxyalkylene block copolymers comprising repeating (AB) units comprising the reaction of a linear, ?,?-(SiH)-functional polydialkylsiloxane (a) with a linear ?,?-(OH)-functional polyoxyalkylene (b) using one or more compounds of elements of main group III and/or the 3rd transition group as catalyst (c), optionally in the presence of a solvent (d), wherein the two reactants (a) and (b) preferably in equimolar amounts and with controlled hydrogen evolution are reacted to quantitative SiH conversion.

Abstract: A process for preparing polyether-siloxane block copolymers by hydrosilylation of alpha,omega-modified hydrosiloxanes with alpha,omega-modified di(meth)allyl polyethers in the presence of a hydrosilylation catalyst, wherein the reaction is performed in a solvent mixture comprising aromatic solvents, polyethers and alkoxylated alcohol, is described.