ИСТИНА

In the presented work specific features of polyelectrolyte behavior and nano structure of the strongly charged sodium polyacrylamido-2-methyl-1-propanesulfonate cryogels were studied. The cryogels were synthesized in frozen water solutions at -150C, the reference gels at 250C. The polyelectrolyte swelling of cryogels is much weaker than that of gels synthesized in solution. The ethanol induced collapse of both gels and cryogels occures stepwise at similar ethanol concentrations. . The elasticity and microporosity structure allows one to squieze a certan part of solvent from the criogel samples. The ability of the cryogels to retain the solvent is almost completely determined by peculiarity of interaction of the solvent with pore walls. In the case of a "good" solvent no mechanical stress can squeeze the greater part of the solvent from the gel. At the same time, in a "poor" solvent upon the collapse the portion of solvent in the squeezed cryogel samples decreases from ca 80-90 to 35 40 %. The small-angle X-ray scattering (SAXS) spectra show maxima corresponding to ordered inhomogeneities of 0.5-3.0 nm scale. The positions of the observed maxima depend on the conditions of the synthesis and on the concentration of the polymer in the gels and cryogels. Increasing the ionic strength of the medium leads to partial disappearance of the maxima which suggests lowering of structural ordering. The observed changes in the SAX data can be explained in the framework of the theory [2-3].