title: Alumina-coated graphene nanosheet and its composite of acrylic rubber.
abstract: A graphene was coated with a thin alumina layer to prepare a novel nanosheet which had high thermal conductivity but low electrical conductivity. The nanosheet with minimal aggregation was prepared effectively by first coating it with aluminum tri-sec-butoxide in anhydrous dimethylformamide, followed by rapid calcination in an inert atmosphere after the hydrolysis of the alkoxide. The morphology observed by scanning electron microscopy and elemental mapping by energy-dispersive X-ray spectrometry showed that the alumina layer coated on the graphene surface was uniform and ultra-thin. Thermogravimetry demonstrated that the uniformly coated alumina protective layer substantially improved the thermal stability of the graphene and that the electrically-insulative alumina layer effectively reduced the electrical conductivity of the graphene. The enhanced polar nature of surface as well as the increased surface roughness due to the coated alumina improved the dispersion of the graphene in the polar acrylic rubber matrix and the interaction at the interface. This led to an effective improvement of the thermal conductivity but marginal increase in electrical conductivity by the filler. Tensile modulus increased drastically to as high as 470% for the composite reinforced with the 5 phr (about 2.5 vol%) loading of the alumina-coated graphene.
authors.affiliation: Department of Chemistry, Energy Harvest-Storage Research Center, University of Ulsan, Ulsan 680-749, Republic of Korea.
authors.forename: Trung Dung
authors.initials: TD
authors.lastname: Dao
authors.affiliation: Department of Chemistry, Energy Harvest-Storage Research Center, University of Ulsan, Ulsan 680-749, Republic of Korea.
authors.forename: Hyung-il
authors.initials: HI
authors.lastname: Lee
authors.affiliation: Department of Chemistry, Energy Harvest-Storage Research Center, University of Ulsan, Ulsan 680-749, Republic of Korea. Electronic address: hmjeong@mail.ulsan.ac.kr.
authors.forename: Han Mo
authors.initials: HM
authors.lastname: Jeong
mesh_terms: D000179:Acrylates / Q000737:chemistry*; D000537:Aluminum Oxide / Q000737:chemistry*; D004553:Electric Conductivity; D006108:Graphite / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D053761:Nanocomposites / Q000737:chemistry* / Q000648:ultrastructure; D013052:Spectrometry, X-Ray Emission; D013499:Surface Properties
chemical_list: D000179:Acrylates; D006108:Graphite; D000537:Aluminum Oxide
keywords: Acrylic rubber; Alumina coating; Composite; Conductivity; Graphene; Hybrid nanosheet