CONFORMATION OF POLY(1,3-DIOXOLANE) IN DILUTE AND SEMIDILUTE AQUEOUS-SOLUTIONS

The conformation of poly(1,3-dioxolane) (PDXL) in aqueous solution was studied by light and neutron scattering, by size-exclusion chromatography coupled with light scattering, and by viscosimetry. In the absence of salt, the solutions contain aggregates which cannot be eliminated either by centrifugation or by filtration. These aggregates result in an excess of scattered intensity, but in an intermediate range of q available in neutron scattering experiments, the behaviors in the dilute and in the semidilute regimes are those expected for a polymer in a rather good solvent. The scaling law for the concentration dependence of the screening length xi was obtained: xi = 2.29c-0.73. In the presence of salt, (0.05 and 0.1 N NaCl), there are no more aggregates although the value of LCST is very close to that in pure water. The variation of the radius of gyration with molecular weight was determined as well as the temperature dependencies of the second virial coefficient and intrinsic viscosity for a given sample.