The Effects of the Organic Groups Attached at the Silicone Atoms of the Organosilane-Based Gemini Nonionic Surfactants on Their Surface Activities

A novel trisiloxane gemini nonionic surfactant was synthesized by the reaction of 3-(diethoxy(methyl)silyl)propan-1-amine with hexamethyldisiloxane to get 3-(trisiloxane)propan-1-amine, which was further reacted with glutaroyl dichloride to form the surfactant molecule, N ¹,N ⁵-bis(3-(trisiloxane)propyl)glutaramide (3). Some related compounds were also prepared, including N ¹,N ⁵-bis (3-(trimethoxysilyl)propyl) glutaramide (1), and N ¹,N ⁵-bis(3-(diethoxy(methyl)silyl)propyl)glutaramide (2). All prepared compounds were analyzed by IR, ¹H-NMR and ¹³C-NMR to confirm their structures. Their interfacial activities, including surface tension and wetting ability, were measured. These surface activities were compared each other and a discussion was carried out on how the organic groups attached on the silicone atoms affect their surface tension and wetting ability. To explain the superior surface activities of the molecules 3, a hypothesis was proposed about a cyclic hydrophobic core area that could be formed by the two hydrophobic chains and the linker of the gemini molecule due to the dispersion force (Van der Waals force) between the two trisiloxane moieties, which close the hydrophobic cycle inside the molecule.