Ferroelectric liquid crystal compounds having perfluoroether terminal portions

An achiral fluorine-containing liquid crystal compound of the general formula I:

• ##STR45## where M, N, and P are each independently ##STR46## a, b, and c are each independently zero or an integer of from 1 to 3 with the proviso that the sum of a+b+c be at least 2;
• each A and B are non-directionally and independently a covalent bond, ##STR47## each X, Y, and Z are independently --H, --Cl, --F, --Br, --I, --OH, --OCH.sub.3, --CN, or --NO.sub.2 ;
• each 1, m, and n are independently zero or an integer of 1 to 4, D is ##STR48## and q and q' are independently 1 to 20, and R can be straight chain or branched;
• and
• R.sub.f is (C.sub.x F.sub.2x O).sub.z C.sub.y F.sub.2y+1 where x is independently 1 to 10 for each C.sub.x F.sub.2x O group, y is 1 to 10 and z is 1 to 6.