Abstract: The present invention concerns chiral doping agents allowing a modification to be induced in the spiral pitch of a cholesteric liquid crystal, said doping agents including a biactivated chiral unit at least one of whose functions allows a chemical link to be established with an isomerisable group, for example by radiation, said group possibly having a polymerisable or co-polymerisable end chain. These new chiral doping agents find application in particular in a color display.

Abstract: The present invention concerns chiral doping agents allowing a modification to be induced in the spiral pitch of a cholesteric liquid crystal, said doping agents including a biactivated chiral unit at least one of whose functions allows a chemical link to be established with an isomerisable group, for example by radiation, said group possibly having a polymerisable or co-polymerisable end chain.

Abstract: A liquid crystal composition comprising a low molecular weight liquid crystal in the interior of which a cross-linking network is formed by polymerization of a prepolymer of formula I: ##STR1## X being a non-mesogenic bivalent radical, the free bonds of which form an angle smaller than 180.degree.;B.sub.1 and B.sub.2 being rigid cyclic groups which would confer liquid crystal properties to the prepolymer if X was such that=180.degree..R.sub.1 and R.sub.2 being the same or different, each representing an optionally substituted alkyl, alkoxy, arylalkyl or aralalkoxy chain;A.sub.1 and A.sub.2 being the same or different, each representing a reactive polymerizable function. Display cells comprising the liquid crystal composition having a low commutation voltage.