A conformational analysis of poly(o1efin sulfone) chains emphasizing the role of third-order Markov correlations of bond conformation resulting from electrostatic interactions between adjacent sulfone dipoles on the main chain led us to prepare terpolymers of SO2, hex-1-ene, and cyclohexene and to study their dielectric behavior at low and high frequencies in dilute solution in order to measure the equilibrium dipole momenta that characterize the ordered structures. Chain stiffness, as measured by the magnitude of the low-frequency relaxing dipole moment, develops strongly in the terpolymers as the mole fraction of hex-1-ene sulfone residues nears unity and is interpreted by a model that falls between the random flight model and the wormlike chain model. Stiff polar segments are created by a sequence of gauche main-chain C-C bonds where the dipoles nest together in favorable electrostatic situations. The size and shape of these stiff segments cannot both be determined, but their configuration is probably close to that of a helix, and their mean content in poly(hex-1-ene sulfone) is about 20-25 atactic hex-1-ene residues. At high frequencies a new form of the time-domain system has found the relaxation time of the segmental relaxation discovered in these terpolymers not to be significantly reduced by the inclusion of a small proportion of cyclohexene sulfone residues, yet the poly(cyc1ohexene sulfone) chain itself is kinetically more flexible.
We report results from time domain reflection measurements for complex permittivities of sodium iodide solutions in methanol, formamide, N-methylformamide, dimethylformamide, dimethylacetamide, propylene carbonate, and dimethyl sulfoxide at concentrations in the range 0.02-1 M. Most of these are at 25 "C with results for methanol and propylene carbonate at lower temperatures to -29 "C. The observed relaxation effects in the range from 100 MHz to 8 GHz were all very nearly of Debye form with relaxation time decreasing slightly with concentration for the hydrogen-bonding solvents, but significantly larger at the highest concentrations in the two aprotic solvents. The decreases in static permitivity with concentration are in all cases larger than predicted by the Hubbardansager theory of kinetic depolarization and the differences correlate better with solvent molecule dipole moments than with static solvent permittivity.
IntroductionUntil recently, decreases in static permittivity and changes in relaxation properties of solutions with increasing concentrations of ions have been interpreted in terms of static effects of ion interactions with polar solvent molecules. Models which have been proposed include saturation of a solvent continuum near the ions, irrotational binding of solvent molecules to ions, and polarizable ion spheres in a polar continuum; these have been reviewed by Hastedl and by Lestrade, Badiali, and Cachet.2 In 1977, Hubbard and Onsager3 pointed out another effect as a result of changing electric fields of ions and solvent dipoles moving in applied electric fields, with counterpolarization of both from the finite dielectric relaxation time of the solvent molecules. The HubbardOnsager4v5 (HO) theory of this kinetic depolarization effect for a continuum model predicts a decrease in solution permittivity proportional to the product of solution conductance and dielectric relaxation time 7D. The first experimental results to be compared with the HO theory, by
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