title: Synthesis of soybean oil-based polymeric surfactants in supercritical carbon dioxide and investigation of their surface properties.
abstract: This paper reports the preparation of polymeric surfactants (HPSO) via a two-step synthetic procedure: polymerization of soybean oil (PSO) in supercritical carbon dioxide followed by hydrolysis of PSO (HPSO) with a base. HPSO was characterized and identified by using a combination of FTIR, (1)H NMR, (13)C NMR, and GPC methods. The effects of HPSO polysoaps on the surface tension of water and interfacial tension of water-hexadecane were investigated as a function of concentration of HPSO and counterion chemistry. HPSO polysoaps were effective at lowering the surface tension of water and the interfacial tension of water-hexadecane. They displayed minimum values of surface tension in the range of 20.5-39.6 dyn/cm at a concentration range of 3.2-32 μM and minimum values of interfacial tension in the range of 15.6-31.44 dyn/cm. The minimum surface and interfacial tension values were highly dependent on the nature of the counterion and increased in the order K(+) < Na(+) < TEA(+). These results suggested that a very low concentration of surfactant can be used to reduce the surface tension of water and interfacial tension of water-hexadecane. Water-hexadecane interfacial energy was also calculated from measured surface tension data using Antonoff, harmonic mean (HM), and geometric mean (GM) methods. Measured values agreed well with those calculated using the HM and GM. The HM method predicted slightly higher values than the GM method, but the Antonoff method did not agree with measured values.
authors.affiliation: Bio-Oils Research Unit, National Center for Agricultural Utilization Research, Agricultural Research Service, U.S. Department of Agriculture , 1815 North University Street, Peoria, Illinois 61604, United States. kevin.liu@ars.usda.gov
authors.forename: Zengshe
authors.initials: Z
authors.lastname: Liu
authors.forename: Girma
authors.initials: G
authors.lastname: Biresaw
mesh_terms: D002245:Carbon Dioxide; D009682:Magnetic Resonance Spectroscopy; D058105:Polymerization; D013024:Soybean Oil / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D013500:Surface Tension; D013501:Surface-Active Agents / Q000138:chemical synthesis* / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D013501:Surface-Active Agents; D014867:Water; D002245:Carbon Dioxide; D013024:Soybean Oil