The Wettability of PMMA Surface by Aqueous Solutions of Anionic Gemini Surfactants with Different Hydrophobic Carbon Chain Lengths

This study investigates the synthesis of several new Gemini surfactants with various hydrophobic carbon chain length amide groups (C12, C14, C16, and C18) using triethylenetetramine, maleic anhydride, and internal olefins with different carbon chain lengths as raw materials. The research examined the adsorption mechanism and hydrophilic modification capacity of four different kinds of Gemini surfactants on the polymethyl methacrylate (PMMA) surface. Surface tension and contact angle data for each Gemini surfactant were used to compute the adhesion work and adhesion tension. According to the surface activity parameters, the critical micelle concentration and maximum adsorption amount decrease with the increase in the length of the hydrophobic carbon chain. However, the equilibrium surface tension first decreases and then increases with the increase in the length of the hydrophobic carbon chain. The four surfactants exhibit complex self-aggregation behavior in the solution due to their long hydrophobic chain structure and flexible spacer. The four surfactants are heavily adsorbed on the PMMA surface, forming semicolloidal aggregates, according to the combination of contact angle measurements, adhesion tension, and interfacial tension data. Moreover, compared with literature, the four surfactants synthesized in this study show better hydrophilic modification ability on the PMMA surface.