Polyelectrolytes and Polycomplexes for Stabilizing Sandy Grounds

Interaction of the anionic copolymer of acrylic acid and acrylamide with a molar ratio of monomer units of 75 : 25 and poly(N,N′-diallyl-N,N′-dimethylammonium chloride) in aqueous solution is studied. The interaction is accompanied by the formation of a polycomplex stabilized by multiple salt bonds between oppositely charged groups of both polyelectrolytes. A nonstoichiometric polycomplex with a tenfold excess of anionic groups is present in solution in the form of particles with a diameter of about 300 nm; the particles retain their aggregate stability for 30 days. The application of aqueous solutions of individual polymers and the nonstoichiometric polycomplex on the surface of sand with a particle size of 0.15 ± 0.05 mm is associated with the formation of composite polymer-sand coatings. The highest mechanical strength is possessed by coatings with the participation of an anionic copolymer and a polycomplex. For sand and polycomplex coatings, the weight loss during water treatment is 10%, which is lower than that in the case of traditional polyacrylamide soil stabilizer. The polycomplex at a concentration of up to 0.33 wt % does not exhibit toxicity to microorganisms, thereby indicating that the use of a negatively charged polycomplex is promising for obtaining waterproof protective coatings on the surface of sandy soils.