title: Multiwalled Carbon Nanotubes at the Interface of Pickering Emulsions.
abstract: 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.
authors.affiliation: School of Chemical, Biological and Materials Engineering, University of Oklahoma , Norman, Oklahoma 73019, United States.
authors.forename: Nicholas M
authors.initials: NM
authors.lastname: Briggs
authors.affiliation: School of Chemical, Biological and Materials Engineering, University of Oklahoma , Norman, Oklahoma 73019, United States.
authors.forename: Javen S
authors.initials: JS
authors.lastname: Weston
authors.affiliation: School of Chemical, Biological and Materials Engineering, University of Oklahoma , Norman, Oklahoma 73019, United States.
authors.forename: Brian
authors.initials: B
authors.lastname: Li
authors.affiliation: School of Chemical Engineering, Oklahoma State University , Stillwater, Oklahoma 74078, United States.
authors.forename: Deepika
authors.initials: D
authors.lastname: Venkataramani
authors.affiliation: School of Chemical Engineering, Oklahoma State University , Stillwater, Oklahoma 74078, United States.
authors.forename: Clint P
authors.initials: CP
authors.lastname: Aichele
authors.affiliation: School of Chemical, Biological and Materials Engineering, University of Oklahoma , Norman, Oklahoma 73019, United States.
authors.forename: Jeffrey H
authors.initials: JH
authors.lastname: Harwell
authors.affiliation: School of Chemical, Biological and Materials Engineering, University of Oklahoma , Norman, Oklahoma 73019, United States.
authors.forename: Steven P
authors.initials: SP
authors.lastname: Crossley
mesh_terms: D000473:Alkanes / Q000737:chemistry; D004655:Emulsions / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D037742:Nanotubes, Carbon / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D000473:Alkanes; D004655:Emulsions; D037742:Nanotubes, Carbon; D013501:Surface-Active Agents; D014867:Water; C007548:n-dodecane