Nonionic Gemini Surfactants With Outstanding Surface Activity and Wetting Properties

Nonionic surfactants with excellent surface tension reduction and wetting properties have great potential in semiconductor development and industrial cleaning applications. In this study, we have synthesized three nonionic gemini surfactants, designated as NGS1 (n = 4), NGS2 (n = 7), and NGS3 (n = 11), with varying lengths of polyoxyethylene chains. The critical micelle concentrations (CMC) of NGS1, NGS2, and NGS3 are determined to be 0.775, 0.852, and 0.889 mmol/L, respectively. Correspondingly, their surface tensions at the CMC (gamma(CMC)) are found to be 30.04, 31.15, and 32.07 mN/m. The low values of gamma(CMC) exhibit more remarkable surface tension reduction capabilities compared to commercial nonionic surfactants (Tween-80 and Brij-35), demonstrating their outstanding surface activity. Moreover, the contact angles of the NGS1, NGS2, and NGS3 solutions undergo substantial reductions, achieving values as low as 53 degrees, 58 degrees, and 62 degrees on polytetrafluoroethylene, respectively, indicating much better wetting properties than Tween-80 (76 degrees) and Brij-35 (83 degrees). Our study gains insight into the relationship between the molecular structures and the surface properties, motivating researchers to develop more advanced surfactants for industrial cleaning and semiconductor development.