Hypothesis

The properties of conventional surfactants (c-surfactants) are generally accepted to be amphipathicity-dominated, but extended surfactants (e-surfactants) are additionally polypropylene oxide (PPO)-dependent; this additional property makes us wonder how an intramolecular PPO spacer would be “extended” at various interfaces and what is responsible for the excellent all-round properties of e-surfactants.

Experiments

A series of novel sodium medium alkyl chain PPO-b-PEO sulfates (2-ethylhexyl polypropylene oxide-block-polyethylene oxide sulfates, C₈P_pE_eS) were designed, synthesized and structurally identified. Tensiometry was applied to estimate the surfactant shape at the air/water surface. Surface tension, interfacial tension, emulsifying power, electrolyte tolerance, adsorption onto oil sands and thermal hydrolysis stability were measured to evaluate the effect of the PPO coil on the interfacial and micellar properties of the e-surfactants.

Findings

On the basis of obtaining greater values for e-surfactants than c-surfactants for both surface area (a_m) per surfactant molecule and the corresponding shape factor (S), we were surprised to find that e-surfactants form a rugby ball shape not only at the air/water surface but also at the oil/water interface; this result is potentially explained by the PPO spacer coiling and collapsing to produce dense packing at the monolayer adsorption, which is rationally borrowed by other interfaces. Many positive or negative correlations were observed between the interfacial/micellar properties of C₈P_pE_eS and a_m values, which seems that the surfactant shape dominants the properties of the e-surfactants. In fact, the properties of C₈P_pE_eS are dominated by the dynamic amphipathicity and assisted by the rugby ball shape of the molecules because of both being driven by the dynamic biphasic affinity of the PPO coil in response to the external environment; these findings provide soft interfacial materials specially adapted for surfactant flooding.

中文翻译：

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什么决定了扩展表面活性剂的界面特性：两亲性或表面活性剂形状？

假设

常规的表面活性剂（c-表面活性剂）的性能通常被认为是两亲性主导的，但是扩展的表面活性剂（e-表面活性剂）还依赖于聚环氧丙烷（PPO）。这种附加的特性使我们想知道分子内PPO间隔基将如何在各种界面上“延伸”，以及电子表面活性剂具有出色的全方位性能的原因是什么。

实验

设计，合成和结构鉴定了一系列新颖的钠中等烷基链PPO- b -PEO硫酸盐（2-乙基己基聚环氧丙烷-嵌段-聚环氧乙烷硫酸盐，C ₈ P _p E _e S）。应用张力测定法估算空气/水表面的表面活性剂形状。测量表面张力，界面张力，乳化能力，电解质耐受性，在油砂上的吸附和热水解稳定性，以评估PPO卷材对电子表面活性剂的界面和胶束性能的影响。

发现

基于每个表面活性剂分子的表面积（a _m）和相对应的形状因子（S），电子表面活性剂均比c表面活性剂获得更大的价值，我们惊讶地发现电子表面活性剂形成的橄榄球形状不像橄榄球一样不仅在空气/水表面，而且在油/水界面；该结果可能是由于PPO垫片在单层吸附过程中盘绕和折叠以产生致密堆积而可能解释的，而其他界面则是合理借用的。C的界面/胶束特性之间观察到许多正或负相关₈ P _p Ë _Ë S和一_米值，似乎表面活性剂的形状占主导地位的电子表面活性剂。实际上，C ₈ P _p E _e S的特性主要受动态两亲性的影响，并受橄榄球的球形影响，因为这两种特性均受PPO线圈对外部环境的动态双相亲和力的驱动。这些发现提供了特别适用于表面活性剂驱油的软界面材料。