Interfacial activity of amino acid-based glycerol ether surfactants and their performance in stabilizing O/W cosmetic emulsions
Interfacial activity of amino acid-based glycerol ether surfactants and their performance in stabilizing O/W cosmetic emulsions
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DOI：
10.1016/j.colsurfa.2014.02.033
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发表时间：
2014-10
期刊：
影响因子：
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通讯作者：
C. Ampatzidis;E-M. A. Varka;T. Karapantsios
中科院分区：
文献类型：
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作者：
C. Ampatzidis;E-M. A. Varka;T. Karapantsios
生物相容性和可生物降解的苯基和酪氨酸甘油醚表面活性剂分子是生态友好型化妆品乳液的良好候选者。这两种分子都有一个疏水性的烷基链，有12个碳原子，但在亲水性的头部有不同的氨基酸：苯丙氨酸（PhGE 12）和酪氨酸（TyrGE 12）。本研究报告了将甘油醚表面活性剂溶解在有机相（橄榄油）和含有非离子聚（氧乙烯）（20）脱水山梨糖醇单油酸酯（商品名吐温80）的水相中的液/液界面的活性。测量指的是a）通过液滴轮廓张力测定法和液滴体积张力测定法的动态表面张力和B）通过振荡液滴轮廓分析的界面粘性粘弹性。结果表明，PhGE 12与TyrGE 12相比，具有更低的界面张力值和更快的界面吸附速度，而两种表面活性剂的界面粘弹性值相当。制备水包油乳液，并通过监测分层指数的时间演变来评估其稳定性。为了解释观察结果，采用乳液的初始液滴尺寸分布和表观体积粘度的测量。结果表明，在相同表面活性剂浓度下，PhGE 12乳剂的稳定性优于TyrGE 12乳剂。这可能归因于PhGE 12乳液中较低的界面张力，其产生的液滴粒径分布更富含中等粒径（约50 μm）和小粒径（约0.5 μm）的液滴，并且其表观粘度更高。另一方面，增加任一种表面活性剂的浓度导致乳液稳定性的显著增加，这与较低的界面张力和较高的表观粘度测量结果一致，但不同意对表面活性剂浓度、液滴尺寸分布和界面粘性粘弹性的不敏感性。
Biocompatible and biodegradable molecules of Phenyl- and Tyrosine-glycerol ether surfactants are good candidates for eco-friendly cosmetic emulsions. Both molecules have a hydrophobic alkyl chain with 12 carbon atoms, but different amino acids in the hydrophilic head: phenylalanine (PhGE12) and tyrosine (TyrGE12). This study reports on the activity of liquid/liquid interfaces with the glycerol ether surfactants being dissolved in the organic phase (olive oil) and the aqueous phase containing the non-ionic poly(oxyethelene) (20) sorbitan monooleate (trade name Tween 80). Measurements refer to a) dynamic surface tension by drop profile tensiometry and drop volume tensiometry and b) interfacial dilatational viscoelasticity by oscillating drop profile analysis. It is shown that PhGE12attains much lower interfacial tension values and exhibits faster interfacial adsorption than TyrGE12whereas interfacial dilatational viscoelasticity values are comparable between the two surfactants. Oil-in-water emulsions are prepared and their stability is assessed by monitoring the time evolution of creaming index. To interpret observations, measurements of the emulsions’ initial droplet size distributions and apparent bulk viscosity are employed. It is found that at similar surfactant concentrations, PhGE12emulsions exhibit better stability than TyrGE12emulsions. This might be attributed to the lower interfacial tension in PhGE12emulsions that yield droplet size distributions richer in intermediate (∼50 μm) and small size (∼0.5 μm) droplets and to their higher apparent viscosities. On the other hand, increasing the concentration of either surfactant leads to a substantial increase of emulsions stability which is in line with the lower interfacial tension and higher apparent viscosity measurements but does not agree with the insensitive versus surfactant concentration droplet size distributions and interfacial dilatational viscoelasticity.