Briggs Nicholas M, Weston Javen S, Li Brian, Venkataramani Deepika, Aichele Clint P, Harwell Jeffrey H, Crossley Steven P
School of Chemical, Biological and Materials Engineering, University of Oklahoma , Norman, Oklahoma 73019, United States.
School of Chemical Engineering, Oklahoma State University , Stillwater, Oklahoma 74078, United States.
Langmuir. 2015 Dec 8;31(48):13077-84. doi: 10.1021/acs.langmuir.5b03189. Epub 2015 Nov 24.
Carbon nanotubes exhibit very unique properties in biphasic systems. Their interparticle attraction leads to reduced droplet coalescence rates and corresponding improvements in emulsion stability. Here we use covalent and noncovalent techniques to modify the hydrophilicity of multiwalled carbon nanotubes (MWCNTs) and study their resulting behavior at an oil-water interface. By using both paraffin wax/water and dodecane/water systems, the thickness of the layer of MWNTs at the interface and resulting emulsion stability are shown to vary significantly with the approach used to modify the MWNTs. Increased hydrophilicity of the MWNTs shifts the emulsions from water-in-oil to oil-in-water. The stability of the emulsion is found to correlate with the thickness of nanotubes populating the oil-water interface and relative strength of the carbon nanotube network. The addition of a surfactant decreases the thickness of nanotubes at the interface and enhances the overall interfacial area stabilized at the expense of increased droplet coalescence rates. To the best of our knowledge, this is the first time the interfacial thickness of modified carbon nanotubes has been quantified and correlated to emulsion stability.
碳纳米管在双相体系中表现出非常独特的性质。它们的颗粒间吸引力导致液滴聚并速率降低，进而提高了乳液稳定性。在此，我们使用共价和非共价技术来改变多壁碳纳米管（MWCNT）的亲水性，并研究它们在油水界面处的行为。通过使用石蜡/水和十二烷/水体系，结果表明，界面处MWNT层的厚度以及由此产生的乳液稳定性会因用于修饰MWNT的方法不同而有显著差异。MWNT亲水性的增加会使乳液从油包水型转变为水包油型。发现乳液的稳定性与占据油水界面的纳米管厚度以及碳纳米管网络的相对强度相关。表面活性剂的添加会降低界面处纳米管的厚度，并以增加液滴聚并速率为代价提高整体稳定的界面面积。据我们所知，这是首次对修饰碳纳米管的界面厚度进行量化，并将其与乳液稳定性相关联。
