Research On The Relationships Of Structure To Properties Of Alkylphenol Anionic-Nonionic Surfactants With Different Carbon Chains

The properties and behaviors on the oil-water interface of alkylphenol anionic-nonionic surfactants with different carbon chains were studied through molecular dynamics simulation.The simulation were used by Gromacs and Gromos53A6 force field,the main research contents include behaviors on the interface;interface properties;heat resistance and salt tolerance and these properties’ variation trend with different carbon chain.The comparative experients happened at different temperatures,different ions and concentration.For analyzing the interface behaviors,the octylphenol polyoxyethylene ether sulfonate(OPES)were used as an example.Results showed that OPES could weaken tension of the oil-water interface significantly. The interface tension is only 3.85 m N·m-1 at OPES saturation. sulfonic group in OPES is the main hydrophilic group and has good hydrophilcity. The interface tension declines from 9.96 m N·m-1 to 6.43 m N·m-1 when temperature increases from318 K to 373 K, indicating the good high temperature resistance of OPES. OPES maintains stable properties within 1%-5% Na+ concentration, with only 1.46 m N·m-1 increase of the interface tension.To compare the alkylphenol anionic-nonionic surfactants with different carbon chains could find the following results:the oil-water interfacial tension could get minimum value and could get the best interfacial activity,the force between sulfonic group and water will be decrease a bit when the carbon chain increases;surfactants studied by this thesis all could weaken interfacial tension significantly;Every surfactant’interfacial tension declines when temperature increases from 318 K to373K;The interfacial tension only has a bit increase within 1%-5%ions concentration and the sulfonic group does not sensitive to the cation.Therefore,the surfactants could tolerate higher Na+ concentration than Mg2+and the last is Ca2+.