Surface Activity and Defoaming Performance of Dilute Aqueous Solutions Containing a Mixture of Phosphate-Ester...

Phosphate-ester poly(ether trisiloxane) (PATS) surfactants have attracted considerable attention due to their excellent emulsifying ability, wetting performance, antistatic properties, and corrosion- and rust-inhibiting characteristics, which enable their wide application in daily chemicals, pesticides, pharmaceuticals, leather processing, and papermaking. In this study, 1,1,1,3,5,5,5-heptamethyltrisiloxane and allyloxy poly(oxyethylene ether) (APEG-400) were used as raw materials to synthesize the intermediate HPETS under the catalysis of chloroplatinic acid, followed by phosphorylation with phosphoric acid to obtain a PATS. The surface activity, thermodynamic properties, thermal stability, aggregation behavior, wetting ability, and foaming characteristics of the PATS/dodecyltrimethylammonium bromide (DTAB) mixed system were systematically investigated. The results indicate that PATS exhibits excellent surface activity, with a critical micelle concentration (CMC) of 5 g/L and a surface tension at CMC (γCMC) of 17.74 mN/m. Furthermore, thermodynamic analysis and aggregation studies reveal a pronounced synergistic interaction between PATS and DTAB. When the mixing ratio of PATS to DTAB is 1:2, the surface tension at CMC decreases to 15.57 mN/m and the CMC is reduced to 0.417 g/L, accompanied by enhanced wetting performance. In addition, PATS functions as an effective defoaming component, enabling efficient regulation of the foaming behavior of the DTAB system. These findings provide important insights into the interfacial behavior and synergistic mechanisms of trisiloxane-based surfactant mixtures, and highlight their potential applications in papermaking, textile processing, and industrial cleaning.