Imprinting chiral structure on liquid crystalline elastomers

Networks have been prepared which exhibit a chiral nematic phase without th e presence of a net overall local chirality. These materials were formed by cross-linking a nematic achiral side chain polymer in a N* phase induced t hrough the addition of chiral dopant. The dopant was then totally removed a nd the resultant elastomer continued to show an N* phase. The phase was mon itored by selective reflection and circular dichroism and was recovered on cooling from the isotropic phase, The pitch of the N* helix was observed to have decreased to 70% of its initial value. In contrast to the behaviour o f a mixture of the polymer and dopant, the imprinted network exhibited a ma rked reduction in the temperature dependence of the pitch of the N* phase.