A pH-Responsive Foam Formulated with PAA/Gemini 12-2-12 Complexes

CLAUDIA DOMINGUEZ; HERNAN RITACCO; FERNÁNDEZ LEYES, MARCOS D.; HERNÁN MARTINELLI; SERGIO MOYA

Colloids and Interfaces

MDPI

Lugar: Basel; Año: 2021 vol. 5

In the search for responsive complexes with potential applications in the formulation ofsmart dispersed systems such as foams, we hypothesized that a pH-responsive system could beformulated with polyacrylic acid (PAA) mixed with a cationic surfactant, Gemini 12-2-12 (G12). Westudied PAA-G12 complexes at liquid?air interfaces by equilibrium and dynamic surface tension,surface rheology, and X-ray reflectometry (XRR).We found that complexes adsorb at the interfacessynergistically, lowering the equilibrium surface tension at surfactant concentrations well below thecritical micelle concentration (cmc) of the surfactant. We studied the stability of foams formulatedwith the complexes as a function of pH. The foams respond reversibly to pH changes: at pH 3.5,they are very stable; at pH > 6, the complexes do not form foams at all. The data presented heredemonstrate that foam formation and its pH responsiveness are due to interfacial dynamics.