Mechanism of dye solubilization and de-aggregation by urea. (September 2021)

• Record Type: Journal Article
• Authors: Perry, James M.; Nagai Kanasaki, Yu; Karadakov, Peter B.; Shimizu, Seishi
• Is Part Of: Dyes and pigments. Volume 193(2021)
• Publication Date: 2021-09
• Subjects: Dye -- Urea -- Solubility -- Aggregation -- Statistical thermodynamics -- Water structure; Dyes and dyeing -- Periodicals; Pigments -- Periodicals; 667.2
• DOI: 10.1016/j.dyepig.2021.109530
• Languages: English
• ISSNs: 0143-7208

Abstract

Abstract: Urea is an effective solubilizer for dyes with low aqueous solubility. To establish, at a molecular level, the reason behind the action of urea as an effective solubilizer, we employ a rigorous statistical thermodynamics approach based on the Kirkwood-Buff theory of solutions. We show that (i) contrary to the classical hypothesis on "water structure breaking", the effect of urea on dye hydration makes a minor contribution to solubilization; (ii) the driving force of solubilization is the accumulation of urea around hydrophobic dye molecules. Highlights: Why urea is an effective dye solubilizer was clarified using statistical thermodynamics. The effect of urea on dye hydration makes a minor contribution to solubilization. The accumulation of urea around hydrophobic dye molecules drives solubilization.