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Small-angle neutron scattering has been used to ascertain the configuration of a random thermotropic terpolyester at three temperatures between the glass transition and the melting point on four fractions of different molecular weight. Specimens were prepared by casting films from solutions and subsequent annealing at selected temperatures for 1 h. All samples have a small amount of crystallinity, but at the lowest annealing temperature, 448 K, the molecules have a random-coil configuration. At the two higher annealing temperatures, 493 and 523 K, the molecules become increasingly stiff. This is observed as an increase in the persistence length from 9 Á at 448 K to ca. 44 A at 523 K. The variation of the ratio (s2)w/Mw with Afw for the two higher temperatures displayed the characteristics of a Kratky-Porod wormlike chain. Persistence lengths and shift factors were obtained from an extrapolation procedure based on an approximation for the dependence of the radius of gyration of a wormlike chain on the contour length and persistence length. The value of the persistence length obtained at 523 K is in good agreement with a value obtained from scanning tunneling microscopy elsewhere. These data suggest that the transformation to the nematic mesophase at temperatures above the melting point is aided by stiffening of the molecule at lower temperatures.

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Interpenetrating networks have been prepared using poly(dimethylsiloxane) as the host network and polymethacrylic acid as the guest network, i.e. polymerised and crosslinked in the presence of the siloxane network. These networks were swollen to equilibrium in dilute aqueous potassium chloride solutions and used as membranes to separate a solution of potassium chloride from pure water. The concentration of potassium chloride either side of each membrane was monitored as a function of time by conductivity measurements. From these data, the diffusion coefficient of potassium chloride in the membranes was calculated as a function of polymethacrylic acid content for temperatures of 303, 318 and 333K. Values of the diffusion coefficient were between 3 x 10−7cm2s−1 and 19 x 10−5 cm2 s−1. The activation energy of the diffusive process decreased linearly with the increase in water content of the networks.