Year: 2025
Type: article
Abstract: Objectives. The study set out to investigate the state of poly(N,N-diallyl-N,N-dimethylammonium chloride) (polyDADMAC) in aqueous solutions and the exchange reactions of polyelectrolyte anions with anions of inorganic acids, as well as to assess the effect of the acidity, basicity, and nature of НnXm acids on the state of the polymer-colloidal complex (PCC) in aqueous solutions. Methods. Potentiometry, dynamic light scattering, infrared spectroscopy, and nuclear magnetic resonance spectroscopy methods were used. Results. The main factors affecting the state of the polyDADMAC polyelectrolyte in aqueous solutions were determined along with the characteristics of exchange processes involving anions of inorganic acids. The polymer electrolyte polyDADMAC is shown to exist in an aqueous solution in the form of impermeable polymer coils, representing polymer solvent-separated ion pairs. The Cl− anion of the polyelectrolyte is exchanged for the OH− ion of water or the Xn− anions of inorganic acids to form PCCs with polymer chain links and various counteranions. The exchange of the anions takes place mainly on the surface of the polymer coil, which limits the degree of substitution of anions and depends on the strength, nature, and basicity of the НnXm acids. A relationship was found between the degree of substitution of the Xn− anions of the polymer coil and the strength of the resulting PCC with the enthalpy of solvation of inorganic acids НnXm. Conclusions. The polymer electrolyte polyDADMAC exists in an aqueous solution in the form of impermeable polymer coils, which are represented by polymer solvent-separated ion pairs. The exchange of the Cl− anion of the polyelectrolyte for the OH− ion of water or the Xn− anions of inorganic acids results in the formation of PCCs with polymer chain links and various counteranions. The exchange of the anions, which takes place on the surface of the polymer coil, mainly involves the OH− anion of the polyelectrolyte. A relationship was identified between the state of polymer coils of polyDADMAC, the degree of substitution of anions with different pKa , and the degree of acid solvation. The degree of substitution of the Xn– anions of acids, which decreases with a decrease in the strength of the НnXm acid and the charge of the resulting anion in the series HClO4 > HCl > HNO3 > HBF4 > HSO4 −, H2PO4 −, is characterized by a significant change in the size of the coil of the slow mode of motion of the PCC polyelectrolyte. Here, the increased diffusion coefficient from 3.0·10−13 to 1.3·10−10 cm2/s corresponds to a decrease in the degree of association of the links of the polymer coil of PCC in the same series. The degree of substitution of the Xn– anions of the polymer coil and the strength of the forming PCC decrease symbatically with a decrease in the degree of solvation of inorganic acids in water.
Source: Fine Chemical Technologies
Authors: Yaroslava N. Golubeva, Alexander V. Krylov, Tatyana A. Chebotareva
Institution: MIREA - Russian Technological University
Language: English
Subfield: Physical and Theoretical Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W4413920759