Polymerizable fatty acid surfactant: Encapsulation of organic pigments for excellent colloidal stability in aqueous solution and water-repellent property

Organic pigments are indispensable in various applications due to their vibrant colors and durability, yet their low polarity often hinders their dispersion in an aqueous solution, leading to large aggregation and sedimentation. To address these limitations, dispersants and encapsulation techniques have been explored. In this study, nanoscale encapsulated pigments were synthesized using a novel polymerizable surfactant, sodium 11-methacrylamidoundecanoic acid (NaMAAUA), along with hydrophobic monomer of styrene or butyl methacrylate. NaMAAUA contains a pendant group of amphiphilic fatty acid, and acts as a dispersant and emulsifier, forming a copolymer shell around the pigments. The apolar tail in NaMAAUA provides hydrophobic interaction with pigments, and the polar carboxyl headgroup exposes in the water phase and enables the formation of strong hydrogen bonds with cellulose. Therefore, the resulting encapsulated pigment exhibits excellent dispersion stability, water-repellent property, washing fastness and UV resistance when applied to paper and cotton fabric, expanding the practical utility of organic pigments in an environmentally conscious manner. Characterization via various analytical techniques validates the efficacy of this approach, paving the way for enhanced pigment applications.