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Design of Surfactant Tails for Effective Surface Tension Reduction and Micellization in Water and/or Supercritical CO2
Langmuir ( IF 3.7 ) Pub Date : 2020-11-23 , DOI: 10.1021/acs.langmuir.0c02835 Christopher Hill 1 , Yasushi Umetsu 2 , Kazuki Fujita 2 , Takumi Endo 2 , Kodai Sato 2 , Atsushi Yoshizawa 2 , Sarah E. Rogers 3 , Julian Eastoe 1 , Masanobu Sagisaka 2
Langmuir ( IF 3.7 ) Pub Date : 2020-11-23 , DOI: 10.1021/acs.langmuir.0c02835 Christopher Hill 1 , Yasushi Umetsu 2 , Kazuki Fujita 2 , Takumi Endo 2 , Kodai Sato 2 , Atsushi Yoshizawa 2 , Sarah E. Rogers 3 , Julian Eastoe 1 , Masanobu Sagisaka 2
Affiliation
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The interfacial properties and water-in-CO2 (W/CO2) microemulsion (μE) formation with double- and novel triple-tail surfactants bearing trimethylsilyl (TMS) groups in the tails are investigated. Comparisons of these properties are made with those for analogous hydrocarbon (HC) and fluorocarbon (FC) tail surfactants. Surface tension measurements allowed for critical micelle concentrations (CMC) and surface tensions at the CMC (γCMC) to be determined, resulting in the following trend in surface activity FC > TMS > HC. Addition of a third surfactant tail gave rise to increased surface activity, and very low γCMC values were recorded for the double/triple-tail TMS and HC surfactants. Comparing effective tail group densities (ρlayer) of the respective surfactants allowed for an understanding of how γCMC is affected by both the number of surfactant tails and the chemistry of the tails. These results highlight the important role of tail group chemical structure on ρlayer for double-tail surfactants. For triple-tail surfactants, however, the degree to which ρlayer is affected by tail group architecture is harder to discern due to formation of highly dense layers. Stable W/CO2 μEs were formed by both the double- and the triple-tail TMS surfactants. High-pressure small-angle neutron scattering (HP-SANS) has been used to characterize the nanostructures of W/CO2 μEs formed by the double- and triple-tail surfactants, and at constant pressure and temperature, the aqueous cores of the microemulsions were found to swell with increasing water-to-surfactant ratio (W0). A maximum W0 value of 25 was recorded for the triple-tail TMS surfactant, which is very rare for nonfluorinated surfactants. These data therefore highlight important parameters required to design fluorine-free environmentally responsible surfactants for stabilizing W/CO2 μEs.
中文翻译：
在水和/或超临界CO 2中有效降低表面张力和胶束化的表面活性剂尾巴的设计
研究了在尾部带有三甲基甲硅烷基（TMS）基团的双和新型三尾表面活性剂的界面性质和CO 2包水（W / CO 2）微乳液（μE）的形成。将这些性能与类似烃（HC）和碳氟化合物（FC）尾部表面活性剂进行比较。表面张力测量允许确定临界胶束浓度（CMC）和CMC处的表面张力（γCMC），导致表面活性FC> TMS> HC出现以下趋势。添加第三条表面活性剂尾部会增加表面活性，并且记录到双/三尾TMS和HC表面活性剂的γCMC值非常低。比较有效尾组密度（ρ各种表面活性剂的层）允许理解γCMC如何受到表面活性剂尾部数目和尾部化学性质的影响。这些结果突出了尾部化学结构对双尾表面活性剂在ρ层的重要作用。但是，对于三尾表面活性剂，由于形成了高密度层，因此很难确定ρ层受尾基结构的影响程度。稳定的W / CO 2 μEs是由双链和三尾TMS表面活性剂二者形成。高压小角中子散射（HP-SANS）已用于表征W / CO 2的纳米结构由双尾和三尾表面活性剂形成的μEs，在恒定压力和温度下，发现微乳液的水核随着水与表面活性剂比率（W 0）的增加而溶胀。三尾TMS表面活性剂的最大W 0值为25，这对于非氟化表面活性剂非常罕见。因此，这些数据突出需要重要的参数来设计无氟环境负责的表面活性剂用于稳定W / CO 2 μEs。
更新日期：2020-12-08
中文翻译：
在水和/或超临界CO 2中有效降低表面张力和胶束化的表面活性剂尾巴的设计
研究了在尾部带有三甲基甲硅烷基（TMS）基团的双和新型三尾表面活性剂的界面性质和CO 2包水（W / CO 2）微乳液（μE）的形成。将这些性能与类似烃（HC）和碳氟化合物（FC）尾部表面活性剂进行比较。表面张力测量允许确定临界胶束浓度（CMC）和CMC处的表面张力（γCMC），导致表面活性FC> TMS> HC出现以下趋势。添加第三条表面活性剂尾部会增加表面活性，并且记录到双/三尾TMS和HC表面活性剂的γCMC值非常低。比较有效尾组密度（ρ各种表面活性剂的层）允许理解γCMC如何受到表面活性剂尾部数目和尾部化学性质的影响。这些结果突出了尾部化学结构对双尾表面活性剂在ρ层的重要作用。但是，对于三尾表面活性剂，由于形成了高密度层，因此很难确定ρ层受尾基结构的影响程度。稳定的W / CO 2 μEs是由双链和三尾TMS表面活性剂二者形成。高压小角中子散射（HP-SANS）已用于表征W / CO 2的纳米结构由双尾和三尾表面活性剂形成的μEs，在恒定压力和温度下，发现微乳液的水核随着水与表面活性剂比率（W 0）的增加而溶胀。三尾TMS表面活性剂的最大W 0值为25，这对于非氟化表面活性剂非常罕见。因此，这些数据突出需要重要的参数来设计无氟环境负责的表面活性剂用于稳定W / CO 2 μEs。
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