Investigation of PDMS gels and solutions by small angle scattering

Measurements of swollen end-linked PDMS gels by means of small angle X-ray and neutron scattering are reported. Hexane and octane were used as solvents. The usual excess scattering associated with frozen-in elastic constraints is observed in the small Q region of the spectra. Contrast variation shows the gels to be chemically homogeneous. In the extended Q range explored, the observed structure factor of the gels is satisfactorily described by a two-term expression, the first of which is of Ornstein-Zernike (lorentzian) form, as in polymer solutions, the second being a squared lorentzian. While the scattering amplitudes associated with these two components decrease in a similar way when the gel is deswollen, the respective correlation lengths are distinct, and exhibit different behaviour. Copyright (C) 1996 Elsevier Science Ltd.