Legge, E J; Paton, K R; Wywijas, M; McMahon, G; Pemberton, R; Kumar, N; Aranga Raju, A P; Dawson, C P; Strudwick, A J; Bradley, J W; Stolojan, V; Silva, S R P; Hodge, S A; Brennan, B; Pollard, A J (2020) Determining the Level and Location of Functional Groups on Few-Layer Graphene and Their Effect on the Mechanical Properties of Nanocomposites. ACS Applied Materials & Interfaces, 12 (11). pp. 13481-13493. ISSN 1944-8244

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Abstract

Graphene is a highly desirable material for a variety of applications, such as nanocomposites, and can be functionalized to alter the ultimate product properties, such as tensile strength. However, often the material properties of the functionalized graphene and the location of any chemical species, attached via different functionalization processes, are not known. Thus, it is not necessarily understood why improvements in product performance are achieved, which hinders the rate of product development. Here, a commercially-available powder containing few-layer graphene (FLG) flakes is characterized before and after plasma or chemical functionalization with either amine or oxide groups. A range of measurement techniques including tip-enhanced Raman spectroscopy (TERS), time of flight secondary ion mass spectrometry (ToF-SIMS) and NanoSIMS were used to examine the physical and chemical changes in the FLG material at both the micro- and nanoscale. These are the first reported TERS measurements on commercially-available graphene, which show the location of the defects (edge vs. basal plane functionalization) and variations in the level of functionalization due to different processing. Nanoscale TERS images of the Raman D-peak intensity reveal variations within sub-micron size flakes and changes due to the different functionalization processes and species. Graphene-polyurethane composites were then produced and the dispersion of the graphitic material in the matrix was visualized using ToF-SIMS. Finally, mechanical testing of the composites demonstrated that the final product performance was enhanced but differed depending on the original material properties of the unfunctionalized and functionalized material.

Item Type:	Article
Keywords:	graphene, commercial, functionalization, composites, characterization, defects, tip-enhanced Raman spectroscopy.
Subjects:	Nanoscience > Surface and Nanoanalysis
Divisions:	Chemical & Biological Sciences
Identification number/DOI:	10.1021/acsami.9b22144
Last Modified:	06 Jul 2020 13:45
URI:	http://eprintspublications.npl.co.uk/id/eprint/8782

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