Synthesis, characterization and surface properties of novel polyether based siloxane surfactants

A series of poly(ethylene glycol) based trisiloxane or tetrasiloxane surfactants have been synthesized via thiol-ene reaction and confirmed by H-1 NMR, C-13 NMR, Si-29 NMR, and FT-IR. The effect of the trimethylsiloxy groups and length of the ethylene glycol (EO) chain on the physicochemical properties, surface tension (gamma), critical micelle concentration (CMC), surface tension at the CMC (gamma(cmc)), adsorption efficiency (pC(20)), surface pressure at the CMC (pi(CMC)), maximum surface excess (Gamma(max)), single siloxane surfactant molecule at the air/water interface (A(min)), and the standard free energy of adsorption (), of these polyether based siloxane surfactants was investigated by surface tension, DLS, and TEM measurement. It indicated that all investigated polyether based siloxane surfactants can reduce the surface tension of water to approximately 21-24 mN center dot m(-1) and the surface activities of silicone surfactants were enhanced with increasing the branched trimethylsiloxy groups and length of the EO chain.