<p>The effect of medium polarity, varied by the addition of ethanol, on counterion condensation processes in aqueous solutions of chitosan aspartate (a weakly charged polyelectrolyte) was studied. It was determined that the dielectric permittivity, specific conductivity, and viscosity index of the polymer system decrease, while the pH increases with increasing ethanol content. This indicates the effects of counterion association with the polycation, leading to the formation of ion pairs and multiplet ionic structures; the addition of EtOH significantly accelerates the associative transformations on macrochains. The influence of the concentration of chitosan aspartate in the system and EtOH in the water-alcohol mixture on the size characteristics and surface charge of the nanoparticles formed during phase segregation of the polymer substance was revealed. A method for spray selective precipitation of a polyelectrolyte solution is proposed with the aim of accelerating the counterion association. It was determined that spherical-, ovoid-, or ellipsoid-shaped nano(micro)particles can be obtained by varying the nature of precipitating liquid (EtOH, BuⁿOH, PrⁱOH, or Me₂CO). The potential benefits of using ionomer nano(micro)particles in biomedical applications and in the field of agrobiotechnology are discussed.</p>