Mechanically Stable Ultrathin Layered Graphene Nanocomposites Alleviate Residual Interfacial Stresses: Implications for Nanoelectromechanical Systems.

Autor:	Vassaux M; Université de Rennes, CNRS, IPR (Institut de Physique de Rennes), UMR 6251, Rennes 35000, France.; Centre for Computational Science, Department of Chemistry, University College London, London WC1H 0AJ, United Kingdom., Müller WA; Centre for Computational Science, Department of Chemistry, University College London, London WC1H 0AJ, United Kingdom., Suter JL; Centre for Computational Science, Department of Chemistry, University College London, London WC1H 0AJ, United Kingdom., Vijayaraghavan A; Department of Materials and National Graphene Institute, The University of Manchester, Manchester M13 9PL, United Kingdom., Coveney PV; Centre for Computational Science, Department of Chemistry, University College London, London WC1H 0AJ, United Kingdom.; Advanced Research Computing Centre, University College London, London WC1H 0AJ, United Kingdom.; Informatics Institute, University of Amsterdam, Amsterdam 1098 XH, The Netherlands.
Jazyk:	angličtina
Zdroj:	ACS applied nano materials [ACS Appl Nano Mater] 2022 Dec 23; Vol. 5 (12), pp. 17969-17976. Date of Electronic Publication: 2022 Dec 14.
DOI:	10.1021/acsanm.2c03955
Abstrakt:	Advanced nanoelectromechanical systems made from polymer dielectrics deposited onto 2D-nanomaterials such as graphene are increasingly popular as pressure and touch sensors, resonant sensors, and capacitive micromachined ultrasound transducers (CMUTs). However, durability and accuracy of layered nanocomposites depend on the mechanical stability of the interface between polymer and graphene layers. Here we used molecular dynamics computer simulations to investigate the interface between a sheet of graphene and a layer of parylene-C thermoplastic polymer during large numbers of high-frequency (MHz) cycles of bending relevant to the operating regime. We find that important interfacial sliding occurs almost immediately in usage conditions, resulting in more than 2% expansion of the membrane, a detrimental mechanism which requires repeated calibration to maintain CMUTs accuracy. This irreversible mechanism is caused by relaxation of residual internal stresses in the nanocomposite bilayer, leading to the emergence of self-equilibrated tension in the polymer and compression in the graphene. It arises as a result of deposition-polymerization processing conditions. Our findings demonstrate the need for particular care to be exercised in overcoming initial expansion. The selection of appropriate materials chemistry including low electrostatic interactions will also be key to their successful application as durable and reliable devices. Competing Interests: The authors declare no competing financial interest. (© 2022 The Authors. Published by American Chemical Society.)
Databáze:	MEDLINE
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