Giant dielectric response and hairpins in polymeric nematics

Abstract

We show that, in contrast to normal polymers, a backbone nematic polymer, with dipoles along the chain axis, yields a dielectric susceptibility increased by a factor of the order of the degree of polymerization. We find (i) a purely exponential variation of susceptibility with temperature, partly reflecting the activiation of hairpin defects of chain conformations and (ii) nonlocality in the response, unlike isotropic polymers. The unusual form of these results suggests (macroscopic) dielectric experiments for finally observing hairpins and studying zero-field chain statistics.