SMALL-ANGLE X-RAY-SCATTERING FROM POLY(VINYL ACETATE) SOLUTIONS AND NETWORKS SWOLLEN IN ACETONE

Small angle X-ray scattering (SAXS) measurements are reported for semidilute poly(vinyl acetate) (PVAc) solutions and gels in good solvent conditions. The results for the solutions are in agreement with the predictions of scaling theory and consistent with the osmotic properties of these solutions obtained from the literature. The correlation length XI-follows a power law behavior in polymer volume fraction-phi, where xi = (2.2 +/- 0.2)phi-0.75 +/- 0.03 angstrom. The gel spectra are compared to those of the solutions, and the second moments describing the static concentration fluctuations are evaluated. A solution-like component is distinguished in the gel signal, the intensity of which is close to that calculated from independent osmotic measurements performed on the same samples. The effective concentration of this component proves to be smaller than the mean concentration of the swollen network.