Imprinting chiral structure on liquid crystalline elastomers

Networks have been prepared which exhibit a chiral nematic phase without the 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 through the addition of chiral dopant. The dopant was then totally removed and the resultant elastomer continued to show an N* phase. The phase was monitored 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 of a mixture of the polymer and dopant, the imprinted network exhibited a marked reduction in the temperature dependence of the pitch of the N* phase.