A silylated polymeric binder, which is soluble or swellable in alkali, bears a plurality of at least one of aliphatic and aromatic hydroxyl groups, at least a portion of which are derivatized by units of the formulae I and II:[(A--B.sub.n).sub.m C]--[(D.sub.o E.sub.p)BC].sub.u (I)and[(D.sub.o E.sub.p)BC].sub.v (II)which are side chains of the polymeric binder, whereinA denotes a silanyl group containing at least 2 silicon atoms in total linked to each other, but not more than 3 silicon atoms linked to each other in an unbranched chain of silicon atoms;B denotes a bridging group;C denotes a functional group which has formed a covalent bond with an aromatic, aliphatic, or cycloaliphatic hydroxyl group of the binder, the group D, or the group E;D denotes a grafted monohydric or polyhydric aliphatic alcohol;E denotes a grafted monohydric or polyhydric aromatic alcohol;n denotes 0 or 1;m denotes 1 or 2; ando, p, u and v each denote 0 or 1.Photosensitive mixtures containing this binder are resistant to plasma etching, stable on storage and have a high thermal stability.