Abstract: The invention is concerned with linear and cyclic polymers or oligomers having a photoreactive ethene group. The polymers are of the formula ##STR1## wherein M.sub.a, M.sub.b, M.sub.c are monomer units for homo- or copolymers;x, y, z are mole fractions of the copolymers, whereby in each case 0<x.ltoreq.1; 0.ltoreq.y.ltoreq.1 and 0.ltoreq.z<1;S.sub.a, S.sub.b are spacer units;Z.sub.a, Z.sub.b are molecule units which can undergo photochemical isomerization/dimerization;n is a magnitude of 4-100 000 andm is 0 or 1,The compounds are used as an orientating layer for liquid crystals.