摘要
研究了全氟辛酸钠与溴化十四烷基三甲铵混合水溶液的表面活性.测定了不同比例混合物水溶液的表面张力-浓度曲线,得出临界胶团浓度(cmc)及临界胶团浓度时的溶液表面张力(γcmc)值.
The surface activity of the mixture of sodium perfluorooctanoate(C7F15CO2Na)and tetradecyltrimethyl ammonium bromide(C14H29N(CH3)3Br)has been investigated.The surface tension(γ)of aqueous solutions of different ratio mixture were measured by drop-volume method.The criticle micelle concentration(cmc)and the surface tension at cmc(γcmc)were read out from theγ-logc curve.By applying Gibbs’adsorption equation and the molecular interaction parameter method,the total adsorption amount(Γt),the composition of adsorbed layer(xFσ)and the composition of micelle were obtained(Tab.1,Fig.1 in Chinese Text).Synergism in surface tension reduction effectiveness and efficiency,and in micelle formation were shown in C7F15CO2Na-C14H29N(CH3)3Br system,as well as in the systems of cationic-anionic surfactants with various CH-chain or with equal length CF-chain and CH-chain.The maximum adsorption amount of this system reaches 7.7×10-10mol·cm-2,more than the capacity of a monolayer,indicating multilayer character.Considering of the similar character of C7F15CO2Na-C8H17N(CH3)3Br system,it is thought that this would be the characteristic of CF-chain and CH-chain surfactants mixed systems.The most peculiar property of this system is that the surface tension reduction effectiveness is not as good as that of C7F15CO2Na-C8H17N(CH3)3Br mixture which showsγcmc minimum value of 15.1mN·m-1,whereas it would be 20.9mN·m-1 in the system investigated in this work,although theγcmc~0 of individual C14H29N(CH3)3Br aqueous solution is 6mN·m-1 lower than that of C8H17N(CH3)3Br.It can be interpreted primitively by widening the application range of Zisman’s viewpoint about the relationship between surface energy and surface composition from solid to liquid.
出处
《化学学报》
SCIE
CAS
1988年第5期413-418,共6页
Acta Chimica Sinica
