A polymer compsn., hardening with water, contains a polyetherpolysiloxane-polyurethane of formula (I) R1, R2 = lower alkyl; m = 5-25; R = a gp. (II); X = lower alkylene: Y = (cyclo)aliphatic, aromatic or araliphatic gp.; Z = polyether residue with 5-150 ethylene oxide and/or propylene oxide gps.; and Y may be substd. by further -NH-C(O)-O-Z-R2 gps..
