S. G. Starodoubtsev

Swelling and collapse of the gel composites based on neutral and slightly charged poly(acrylamide) gels containing Na-montmorillonite

Abstract Clay-polymer hydrogel composites were prepared on the basis of neutral and slightly charged cationic and anionic poly(acrylamide) gels containing different amounts of the clay mineral Na-montmorillonite. The swelling and collapse in water–acetone media and the mechanical behavior of such gels were studied. It is shown that the clay incorporated into neutral poly(acrylamide) gel hardly influences its degree of swelling in water. On the other hand, for the anionic and especially for the cationic gels, the swelling in the presence of clay decreases. The elastic modulus of gels with incorporated clay is higher, while the amplitude of the acetone-induced collapse is lower than for the corresponding pure gel systems.

Poly(acrylamide) gels with embedded magnetite nanoparticles

Magnetic gels are a new class of soft polymer materials with their properties controlled by magnetic fields. A method was developed for the preparation of magnetite nanoparticles in a matrix of poly(acrylamide) gel. Synthesis of the magnetic spinel iron oxide Fe3O4 in a matrix of poly(acrylamide) gel was performed via coprecipitation of Fe(II) and Fe(III) in alkaline medium. The effects of the cross-link density, the concentration of polymer and salt in the swollen network during preparation on the composition, structure and properties of the magnetic gels were studied by electronography, TEM and small-angle X-ray scattering (SAXS). The crystalline lattice of the particles was determined as magnetite. The average size of the particles, d, calculated from the half-width of the diffraction peaks, is of the order of 10 nm. The obtained data demonstrate a marked difference in size distribution of magnetic particles in gels of different structure.