Stabilizers for polymer foams based on recycling of polydimethylsiloxane

A process for producing polyether polydimethylsiloxanes, comprising:

• (a) submitting a cyclic-polydimethylsiloxane-containing composition, comprising at least one cyclic polydimethylsiloxane to an equilibration reaction with at least one poly(methylhydrogen)siloxane in the presence of at least one equilibration catalyst to form a poly(methylhydrogen)-polydimethylsiloxane copolymer;
• and
• (b) submitting the poly(methylhydrogen)-polydimethylsiloxane copolymer obtained in (a) to a hydrosilylation reaction with at least one polyether, comprising at least one carbon-carbon double bond reactive to Si—H bonds to obtain a polyether polydimethylsiloxane;
• wherein the at least one cyclic polydimethylsiloxane is at least partially derived from at least one linear or branched polydimethylsiloxane or copolymer thereof,
• wherein the cyclic-polydimethylsiloxane-containing composition comprises at most 300 ppm water as measured according to DIN 51777:2020-04, based on the total weight of the cyclic-polydimethylsiloxane-containing composition, and
• wherein the at least one linear or branched polydimethylsiloxane or copolymer thereof is contained in a poly dimethylsiloxane-containing composition and wherein the polydimethylsiloxane-containing composition
• comprises at least 500% by weight of the at least one linear or branched polydimethylsiloxane or copolymer thereof, based on the total weight of the polydimethylsiloxane-containing composition;
• and/or
• has a silicon content of from 19% to 38% by weight, based on the total weight of the polydimethylsiloxane-containing composition;
• and/or
• comprises less than 50% by weight based on the total weight of the polydimethylsiloxane-containing composition.