复杂流体的润湿性和表面活性剂封端的纳米诱导的拟通用润湿行为,The Journal of Physical Chemistry B

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复杂流体的润湿性和表面活性剂封端的纳米诱导的拟通用润湿行为
The Journal of Physical Chemistry B ( IF 2.8 ) Pub Date : 2017-06-12 00:00:00 , DOI: 10.1021/acs.jpcb.7b02723
A. R. Harikrishnan ₁ , Purbarun Dhar ₂ , Prabhat K. Agnihotri ₂ , Sateesh Gedupudi ₁ , Sarit Kumar Das _{1,

2}

Affiliation

即使对水性表面活性剂的润湿性进行了大量研究，而对纳米颗粒对胶体的润湿性影响的研究也很少，据作者所知，还没有关于表面活性剂和纳米颗粒改变润湿性的联合作用的报道。。本研究首次报道了表面活性剂和纳米颗粒对复合流体（例如纳米胶体）在不同基质上的润湿性的综合影响的广泛实验和理论研究，范围从亲水性到主要是极性表面能组分（硅晶片）和玻璃）到接近疏水范围，表面能主要是分散成分（铝和铜基材）。进行系统计划的实验，以分离表面活性剂，颗粒以及组合的颗粒和表面活性剂在调节润湿性方面的作用。发现单独的纳米胶体和具有不同表面的表面活性剂封端的纳米胶体相互作用的机理和控制参数完全不同。这篇文章也是第一次，分析了表面性质，表面活性剂和颗粒浓度对接触角以及颗粒和表面活性剂浸渍胶体悬浮液的接触角滞后（CAH）的相互作用。在纳米颗粒悬浮液的情况下，观察到的接触角对于疏水性系统减小，而对于所考虑的亲水性系统则增大。相反，颗粒和表面活性剂的胶体体系结合后，在所有基材上均表现出准独特的润湿行为，即随着颗粒浓度的降低，接触角减小。同样有趣的是，在所有颗粒浓度下，组合的颗粒表面活性剂系统的润湿角远低于在相同表面活性剂浓度下仅表面活性剂情况下的润湿角。基于有效滑移长度的考虑，已经基于粒子，流体和表面活性剂分子的近表面相互作用来解释了这种反直觉的观察。不同表面活性剂和颗粒浓度下胶体悬浮液的CAH分析揭示了对接触线钉扎的深入物理洞察力，并且在接触角和微分能量之间建立了独特的新颖关系，用于扭曲固定无柄液滴的瞬时接触角。根据DLVO（Derjaguin–Landau–Verwey–Overbeek）的原理，在分子尺度上影响的表面能和相互作用参数，对影响润湿性的控制参数进行了详细的理论分析。观察。

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Wettability of Complex Fluids and Surfactant Capped Nanoparticle-Induced Quasi-Universal Wetting Behavior

Even though there are quite large studies on wettability of aqueous surfactants and a few studies on effects of nanoparticles on wettability of colloids, to the best of authors’ knowledge, there is no study reported on the combined effect of surfactant and nanoparticles in altering the wettability. The present study, for the first time, reports an extensive experimental and theoretical study on the combined effect of surfactants and nanoparticles on the wettability of complex fluids such as nanocolloids on different substrates, ranging from hydrophilic with a predominantly polar surface energy component (silicon wafer and glass) to near hydrophobic range with a predominantly dispersive component of surface energy (aluminum and copper substrates). Systematically planned experiments are carried out to segregate the contributing effects of surfactants, particles, and combined particle and surfactants in modulating the wettability. The mechanisms and the governing parameters behind the interactions of nanocolloids alone and of surfactant capped nanocolloids with different surfaces are found to be grossly different. The article, for the first time, also analyzes the interplay of the nature of surfaces, surfactant and particle concentrations on contact angle, and contact angle hysteresis (CAH) of particle and surfactant impregnated colloidal suspensions. In the case of nanoparticle suspensions, the contact angle is observed to decrease for the hydrophobic system and increase for the hydrophilic systems considered. On the contrary, the combined particle and surfactant colloidal system shows a quasi-unique wetting behavior of decreasing contact angle with particle concentration on all substrates. Also interestingly, the combined particle surfactant system at all particle concentrations shows a wetting angle much lower than that of the only-surfactant case at the same surfactant concentration. Such counterintuitive observations have been explained based on the near-surface interactivity of the particle, fluid, and surfactant molecules based on effective slip length considerations. The CAH analyses of colloidal suspensions at varying surfactant and particle concentrations reveal in-depth physical insight into contact line pinning, and a unique novel relationship is established between the contact angle and differential energy for distorting the instantaneous contact angle for a pinned sessile droplet. A detailed theoretical analysis of the governing parameters influencing the wettability has been presented invoking the principles of DLVO (Derjaguin–Landau–Verwey–Overbeek), surface energy and interaction parameters influencing at the molecular scale, and the theoretical framework is found to support the experimental observations.

更新日期：2017-06-13

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