Alam Mohammad Mydul, Aramaki Kenji
Graduate School of Environment and Information Sciences, Yokohama National University, Yokohama, Japan.
Langmuir. 2008 Nov 4;24(21):12253-9. doi: 10.1021/la8021547. Epub 2008 Oct 11.
The formation, stability, and rheological behavior of a hexagonal phase based gel-emulsion (O/H1 gel-emulsion) have been studied in water/C12EO8/hydrocarbon oil systems. A partial phase behavior study indicates that the oil nature has no effect on the phase sequences in the ternary phase diagram of water/C12EO8/oil systems but the domain size of the phases or the oil solubilization capacity considerably changes with oil nature. Excess oil is in equilibrium with the hexagonal phase (H1) in the ternary phase diagram in the H1+O region. The O/H1 gel-emulsion was prepared (formation) and kept at 25 degrees C to check stability. It has been found that the formation and stability of the O/H1 gel-emulsion depends on the oil nature. After 2 min observation (formation), the results show that short chain linear hydrocarbon oils (heptane, octane) are more apt to form a O/H1 gel-emulsion compared to long chain linear hydrocarbon oils (tetradecane, hexadecane), though the stability is not good enough in either system, that is, oil separates within 24 h. Nevertheless, the formation and stability of the O/H1 gel-emulsion is appreciably increased in squalane and liquid paraffin. It is surmised that the high transition temperature of the H1+O phase and the presence of a bicontinuous cubic phase (V1) might hamper the formation of a gel-emulsion. It has been pointed out that the solubilization of oil in the H1 phase could be related to emulsion stability. On the other hand, the oil nature has little or no effect on the formation and stability of a cubic phase based gel-emulsion (O/I1 gel-emulsion). From rheological measurements, it has found that the rheogram of the O/H1 gel-emulsion indicates gel-type structure and shows shear thinning behavior similar to the case of the O/I1 gel-emulsion. Rheological data infer that the O/I1 gel-emulsion is more viscous than the O/H1 gel-emulsion at room temperature but the O/H1 gel-emulsion shows consistency at elevated temperature.
在水/C12EO8/烃油体系中研究了基于六方相的凝胶乳液（O/H1凝胶乳液）的形成、稳定性和流变行为。部分相行为研究表明，油的性质对水/C12EO8/油体系三元相图中的相序列没有影响，但相的域尺寸或油的增溶能力会随油的性质而显著变化。在H1+O区域的三元相图中，过量的油与六方相（H1）处于平衡状态。制备（形成）O/H1凝胶乳液并保持在25℃以检查稳定性。已发现O/H1凝胶乳液的形成和稳定性取决于油的性质。观察2分钟（形成后），结果表明，与长链线性烃油（十四烷、十六烷）相比，短链线性烃油（庚烷、辛烷）更易于形成O/H1凝胶乳液，尽管在这两种体系中稳定性都不够好，即油在24小时内会分离。然而，在角鲨烷和液体石蜡中，O/H1凝胶乳液的形成和稳定性明显提高。据推测，H1+O相的高转变温度和双连续立方相（V1）的存在可能会阻碍凝胶乳液的形成。有人指出，油在H1相中的增溶可能与乳液稳定性有关。另一方面，油的性质对基于立方相的凝胶乳液（O/I1凝胶乳液）的形成和稳定性几乎没有影响。通过流变学测量发现，O/H1凝胶乳液的流变曲线表明其具有凝胶型结构，并且表现出与O/I1凝胶乳液类似的剪切变稀行为。流变学数据推断，在室温下O/I1凝胶乳液比O/H1凝胶乳液更粘稠，但O/H1凝胶乳液在升高温度时表现出稠度。
