The graft copolymers of Polyacrylamide (PAA) to Dextran (M w ¼ 20000 and M w ¼ 70000) have been synthesised by ceric-ion-reduced redox initiation method. Molecular characteristic of graft copolymers were determined from light scattering, SEC, and viscometry data. It was established that the increase of molecular weight of Dextran component up to 3.5 times do not influence essentially organization at molecular level of these copolymers in aqueous solution. Thet D-g-PAA copolymers capable of binding the heavy metal ions.

Dextran-graft-polyacrylamide copolymers with different backbone lengths and graft numbers have been tested as flocculation aids in model kaolin suspensions. According to the sedimentation rate and the final sediment volume the graft copolymers proved to be rather similar to the linear acrylamide homopolymer having similar molecular weight. According to the supernatant liquid clarity the copolymers are more effective flocculants than the linear polyacrylamide. The supernatant clarity is inversely related to the length of backbone between the grafts. Apparently, conformation of grafted chain is somewhat more expanded in the cases where the grafts are closely disposed. Due to an expanded macromolecular conformation the functional groups of these copolymers are more capable of capturing solid particles than those of linear acrylamide polymers.

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Dextran-graft-Polyacrylamide copolymers (D-g-PAA) with a polysaccharide backbone having different molecular weights (Mw = 20 000 and Mw = 70 000) and with various number of PAA-grafts per one Dextran macromolecule have been synthesized. Light scattering and viscometry investigations have shown that the internal structure of D-g-PAA copolymers depends upon the distance between PAA-grafts. Compactness of D20-g-PAA copolymers is lower in comparison with D70-g-PAA samples due to different conformations of PAA grafted chains: a “mushroom” conformation for D70-g-PAA and a “worm-like” one for D20-g-PAA samples.

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