Nonlocal dielectric response in dipolar polymers

Abstract

We calculate the nonlocal dielectric susceptibility $\chi ({\bf r}-{\bf r}')$ for a fluid of rods carrying dipoles pointing along their axes. At short distances, of order the rod diameter, we get a value of χ considerably smaller than that of a fluid of individual monomers. At distances comparable to the rod length, χ climbs to a value N times larger than a fluid of monomers, as expected. In between these two limits dipolar rods are predicted to exhibit a form of Debye-Huckel screening. the relevance to internal field calculations and to direct experiments is pointed out. We also calculate the response of dipolar Gaussian chains.