A COMPARATIVE-STUDY OF THE HIGH-FREQUENCY DIELECTRIC-PROPERTIES OF POLY(ALPHA-GLUTAMATE) AND POLY(GAMMA-GLUTAMATE) AQUEOUS-SOLUTIONS

The dielectric properties of poly(alpha-glutamic acid) and poly(gamma- glutamic acid) aqueous solutions inf the fully ionized state have been investigated in the frequency range from 1 MHz to 1 GHz by means of f requency-domain dielectric spectroscopy measurements. In this frequenc y range, micro-Brownian dynamics and internal motion of side-chain pol ar groups give rise to nonexponential relaxation processes resulting i n an intermediate dielectric relaxation between that due to the counte rion atmosphere polarization and that due to the orientational polariz ation of the water molecules. In this work, we study the influence of the polymer concentration in the dilute-semidilute regime on the diele ctric parameters, i.e., the dielectric increment Delta epsilon and the relaxation time tau, 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 soluti ons. (C) 1997 Wiley & Sons, Inc.