Abstract: Materials of formula (I): [G]g(SiO1/2)x are described where G is R3SiR1R2(O)k; R1, R2, R3 are independently a C1-16 alkyl which may be partly or fully halogenated, H and formula (IA), wherein Y is selected from COO, OCO, O, S, CHOH, CHF, CH2; Q=(CH2)n where one or more non-adjacent methylenes may be replaced by O and n=1=20; Z is O, S, a single covalent bond, COO, OCO; when Y is CH2, then n may also be 0; (a) represents any mesogenic group; provided that at least one of R1, R2, R3, is selected from formula (IA): k=0 or 1; g=4 or 6 or 8 or 10 or 12; 1=3 or 8 provided that: if k=1, 1=3 and x is selected form 6, 8, 10, 12 then g=x; if k=0, 1=8 and g=4 then x=1; and further provided that G may have up to g different structures for any single compound.

Abstract: A material of general formula I: ##STR1## where E=0 indicates a non-cyclic system, and E=1 indicates a cyclic system;G is R.sub.3 SiR.sub.1 R.sub.2 (O).sub.kR.sub.1, R.sub.2, R.sub.3 are independently selected from C.sub.1-16 alkyl which may be partly or fully halogenated, H and formula IA: ##STR2## wherein Y is a propylene group which may be partially halogenated with fluorine or chlorine and Y.sub.1 is independently selected from COO, OCO, O, S, CHOH, CHF, CO or CH.sub.2 ;Q and Q.sub.1 are independently selected from (CH.sub.2).sub.n wherein one or more non-adjacent methylenes may be replaced by O andn=0-20;Z and Z.sub.1 are independently selected from O, S, single covalent bond, COO or OCO; ##STR3## represents a mesogenic group and is given by the general structure II ##STR4## A, B, D are selected from the following rings: ##STR5## the above rings may be substituted with one or more of the following substituents in at least one of the available substitution positions: F, Cl, Br, CH.sub.