title: Spray-Coated Halloysite-Epoxy Composites: A Means To Create Mechanically Robust, Vertically Aligned Nanotube Composites.
abstract: Halloysite nanotube-filled epoxy composites were fabricated using spray-coating methods. The halloysite nanotubes (HNTs) were aligned by the hydrodynamic flow conditions at the spray nozzle, and the polymer viscosity helped to preserve this preferential orientation in the final coatings on the target substrates. Electron microscopy demonstrated a consistent trend of higher orientation degree in the nanocomposite coatings as viscosity increased. The nanoindentation mechanical performances of these coatings were studied using a Hysitron TriboIndenter device. Composites showed improvements up to ∼50% in modulus and ∼100% in hardness as compared to pure epoxy, and the largest improvements in mechanical performance correlated with higher alignment of HNTs along the plane-normal direction. Achieving this nanotube alignment using a simple spray-coating method suggests potential for large-scale production of multifunctional anisotropic nanocomposite coatings on a variety of rigid and deformable substrates.
authors.affiliation: Department of Materials Science and Engineering, Massachusetts Institute of Technology (MIT) , 77 Mass Avenue, Cambridge, Massachusetts 02139, United States.|Department of Chemical Engineering, Massachusetts Institute of Technology , 77 Mass Avenue, Cambridge, Massachusetts 02139, United States.|Department of Mechanical Engineering, Massachusetts Institute of Technology , 77 Mass Avenue, Cambridge, Massachusetts 02139, United States.
authors.forename: Kenan
authors.initials: K
authors.lastname: Song
authors.affiliation: Department of Materials Science and Engineering, Massachusetts Institute of Technology (MIT) , 77 Mass Avenue, Cambridge, Massachusetts 02139, United States.|Department of Chemical Engineering, Massachusetts Institute of Technology , 77 Mass Avenue, Cambridge, Massachusetts 02139, United States.|Department of Mechanical Engineering, Massachusetts Institute of Technology , 77 Mass Avenue, Cambridge, Massachusetts 02139, United States.
authors.forename: Roberta
authors.initials: R
authors.lastname: Polak
authors.affiliation: Department of Materials Science and Engineering, Massachusetts Institute of Technology (MIT) , 77 Mass Avenue, Cambridge, Massachusetts 02139, United States.|Department of Chemical Engineering, Massachusetts Institute of Technology , 77 Mass Avenue, Cambridge, Massachusetts 02139, United States.|Department of Mechanical Engineering, Massachusetts Institute of Technology , 77 Mass Avenue, Cambridge, Massachusetts 02139, United States.
authors.forename: Dayong
authors.initials: D
authors.lastname: Chen
authors.affiliation: Department of Materials Science and Engineering, Massachusetts Institute of Technology (MIT) , 77 Mass Avenue, Cambridge, Massachusetts 02139, United States.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Rubner
authors.affiliation: Department of Chemical Engineering, Massachusetts Institute of Technology , 77 Mass Avenue, Cambridge, Massachusetts 02139, United States.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Cohen
authors.affiliation: Department of Materials Science and Engineering, Masdar Institute of Science and Technology , Abu Dhabi, United Arab Emirates.
authors.forename: Khalid A
authors.initials: KA
authors.lastname: Askar
keywords: alignment; halloysite; mechanical; orientation factor; thin-film coating