The dynamic light scattering method was used to investigate the aqueous solutions of Pluronic P123 under different temperature, solvent, and quercetin additives. Significant changes in the average particle size and polydispersity index were revealed depending on the conditions. The effect of temperature on micelle formation of block copolymer in aqueous solution in the range T=15–45°C, the most commonly considered in the use of P123 in sol-gel synthesis of silica, was studied. The formation of micelles of the studied surfactant was greatly influenced by temperature, especially at T=15–20°C. In this temperature range, the size distribution of the scattering intensity has a polymodal character, which indicates the presence of macromolecules, micelles and their aggregates in the system. Further increase in temperature up to 45°C does not result in a significant change in particle size. In aqueous solutions, micelles with a narrow size distribution (minimum polydispersity index) are formed in the temperature ranges 21–25 and 35–40°C. Significant influence of alkanols and polyphenolic substances additives as solubilizers and able to influence the structure of micelles both in their volume and on the surface of polar parts of surfactants was noted. It is shown that in the presence of butanol-1 the stabilization of micelles at temperatures 15–20°C is observed. At T30°C rearrangements of the mesophase structure occur. As the proportion of butanol-1 in the solution increases, its influence is manifested at lower temperatures. It was noted that ethanol has a destructive effect on micelles. Quercetin additives exhibit the opposite micelle stabilizing effect, leading to the formation of a homogeneous surfactant structure. It is shown that by varying the solvent composition, it is possible to control the binding of flavonoid to micelle by changing the solvation. The greatest influence of quercetin on the structure formation of P123 was observed at the solvent composition corresponding to the molar ratio of ethanol and block copolymer n(EtOH):n(P123)=80:1.
