A comparative study of the high-frequency dielectric properties of poly(α-glutamate) and poly(γ-glutamate) aqueous solutions

The dielectric properties of poly(α-glutamic acid) and poly(γ-glutamic acid) aqueous solutions in the fully ionized state have been investigated in the frequency range from 1 MHz to 1 GHz by means of frequency-domain dielectric spectroscopy measurements. In this frequency range, micro-Brownian dynamics and internal motion of side-chain polar groups give rise to nonexponential relaxation processes resulting in an intermediate dielectric relaxation between that due to the counterion atmosphere polarization and that due to the orientational polarization of the water molecules. In this work, we study the influence of the polymer concentration in the dilute-semidilute regime on the dielectric parameters, i.e., the dielectric increment Δϵ and the relaxation time τ, and discuss their relevance in the light of some scaling pictures recently proposed by Dobrynin, Colby, and Rubinstein to describe the unentangled regime of flexible polyelectrolyte solutions.