Macromolecules, Vol.27, No.25, 7410-7414, 1994
Dielectric Normal-Mode Relaxation of Poly(Lactone)S in Solution
We studied the dielectric normal mode relaxation in dilute and semidilute solutions of poly(epsilon-caprolactone) (PCL) and poly(delta-valerolactone) (PVL) in benzene using narrow distribution samples prepared with an initiator of a lanthanoid complex. The effect of long nonpolar groups separating the polar ester groups on the dielectric behavior was investigated by comparing the present results with those for cis-polyisoprene (PI) solutions reported previously. In dilute solutions, the longest relaxation time tau for both PCL and PVL increased in proportion to M(1.63+/-0.03) . Th, double-logarithmic plots of tau vs [eta]eta(s)M/RT for the dilute solutions as well as those of PI fell on the same universal straight Line irrespective of the solvent quality. Here [eta] and eta(s) are the intrinsic viscosity and the solvent viscosity, respectively. The, dielectric loss factor epsilon" vs frequency f curves for the dilute PCL and PVL solutions agreed with the Zimm theory. In the semidilute solutions, log tau increased linearly with respect to C as predicted by the Muthukumar-Freed theory. The epsilon" curve broadened with C as observed previously for PI semidilute solutions. The dynamical behavior is independent of the local structure. The dielectric relaxation strength Delta epsilon, which is proportional to the mean square end-to-end distance (r(2)), increased with M in dilute solution but decreased with C above the overlap concentration.
Keywords:SEMIDILUTE POLYBUTADIENE SOLUTIONS;PROBE POLYISOPRENE CHAIN;TO-END DISTANCE;DILUTE-SOLUTIONS;CIS-POLYISOPRENE;POLY(2;6-DICHLORO-1;4-PHENYLENE OXIDE);CONCENTRATION-DEPENDENCE;MOLECULAR-WEIGHT;POLYMERS;TIMES