甜菜碱与油酸混合吸附膜的界面扩张流变性质

Interfacial dilational rheological properties of mixed adsorption film formed by betaine and oleic acid

为探究油相中的少量活性物质对吸附膜性质的影响规律,利用滴外形分析方法研究正癸烷中油酸和水相中烷基甜菜碱(XSB)形成的界面混合吸附膜的扩张流变性质,考察了时间、频率、浓度对界面扩张模量和相角的影响规律。结果表明:XSB吸附膜的流变特性主要由其亲水基团决定,膜内重排过程占主导地位,界面吸附膜以弹性为主,动态相角随时间延长逐渐降低;油酸从油相一侧向界面的混合吸附对吸附膜的粘弹特性影响不大,但油酸分子在界面膜内的原位响应导致高浓度时混合吸附膜的强度变弱,界面扩张模量从约60 mN/m降至40 mN/m。

In order to explore the effect of surface-active substance in the oil-phase on the properties of adsorption film,the dilational rheological properties of mixed adsorption films formed by oleic acid in decane and alkylbetaine XSB molecules in aqueous were studied by drop shape analysis method.The influences of time,frequency and concentration on the interfacial dilational modulus and phase angle were investigated.The results show that the rheological nature of XSB adsorption film is determined by hydrophilic groups of betaine and the re-arrangement process in film plays the most important role.As a result,the interfacial adsorption film shows elastic and dynamic phase angle decreases with aging time.The viscoelastic properties vary little when oleic acid molecules adsorb from the oil phase.However,the strength of film becomes weaker at high bulk concentration because of the fast in-situ response of oleic acid molecules in film and the value of interfacial dilational modulus decreases from about 60 mN/m to 40 mN/m.