温度对表面活性剂双水相及期倒置的影响

以实验室合成的N-十二烷基-N-(2-羟乙基)-N,N-二甲基溴化铵(C₁₂HDAB)和N-十二烷基-N,N-二(2-羟乙基)-N-甲基溴化铵(C₁₂DHAB)分别与十二烷基硫酸钠、溴化钠复配，构筑阴、阳离子表面活性剂复合系统双水相.以阳离子表面活性剂过量的双水相(ATPS-C)为例，着重研究温度对ATPS-C的影响.结果表明，双水相可在一定的温度区域内形成；在给定温度范围内升高温度，双水相区的组成宽度有所增大，相区位置略微移向阳离子/阴离子表面活性剂比例增大的方向；改变温度会使双水相发生相倒置现象，通过紫外 可见吸收光谱测定相倒置温度.

Temperature effects on surfactant aqueous two-phase systems

The cationic surfactants, N-dodecyl-N （2-hydroxyethyl）-N,N-dimethyl ammonium bromide （C12 HDAB） and N dodecygN, N-2-dihydroxyethyl-N-methyl ammonium bromide （C12 DHAB）, have been synthesized by the reactions of N, N-dimethyl-N hydroxyethylamine and N-methyl-N, N-2-dihydroxyethylamine with 1-bromododeeane. They are mixed with sodium dodecyl sulfate （SDS） to form anionic/cationic surfactant aqueous two-phase systems with cationic surfactant in ex- cess （ATPS-C）. The temperature effects on the ATPS-C of G2 HDAB/C12DHAB-SDS-NaBr systems has been investiga ted. It follows that the areas of the ATPS-C regions become a little wider and shift slightly to the cationic surfactant side as temperature increases in a certain tempature range. With temperature increasing, the mixed anionic/cationic surfactant sys- tem usually experiences white emulsion, twc~phase system and ATPS disappearing processes. Especially, the phase inver- sion for specific ATPS C can be observed by adjusting the temperature. The system that contains 0.2 mol ~ I） total surfac- tants with the molar ratio 2.2 of the cationic to anionic surfactant and crystal violet or methyl red as a dye, has been chosen to study the phase inversion phenomenon and the variation of the location of the immiscible phases. It can be observed that the dyed phase locates at the bottom at low temperature while it turns to the top at high temperature. UV-Vis absorption spectroscopy has been employed to determine the temperature region of phase inversion from measurements on the absor banee of the upper phase of ATPS-C at different temperature.