Research On The Relationships Of Structure To Properties Of New Cardanol Betaine-type Surfactant

Molecular dynamics simulations of a new sulfobetaine-type zwitterionic surfactant wereperformed at the decane/water interface, the influence of surfactant structure to the interfacialproperties were investigated, including the adsorption behavior, the interfacial tension, theinterfacial thickness, also to temperature sensitivity and salinity resistance.A new method was used to generate forcefield parameters for new surfactant under theresearch of The ATB and Repository （ATB）. Firstly, the molecular geometry structure wasoptimized and the charges were obtained using quantum chemistry software. Then the wholemolecule was split into several fragments and the forcefield parameters of these fragmentswere generated using ATB. The parameters of the whole molecule were generated bymerging the parameters of the fragments. The method was proved to be reasonable.The results show that the surfactant molecules can adsorb at the decane/water interfaceclosely and reduce the interfacial tension significantly between decane and water. Theminimum interfacial tension could reach up to1.6mN·m^-1 when the number of surfactantswas up to134, which corresponds to the critical micelle concentration from the experiment.The hydrophilic property of surfactant was based on hydroxyl groups and the two ionicgroups, however, the surfactant will not become invalid with the increase of the temperaturefrom300K to373K, and instead their interfacial properties were improved because of thehigh temperature.The surfactant was also insensitive to univalent or divalent cations at highconcentrations, this may due to the inner salt structure formed by quaternary amine group andsulfonic group.