Design and development of 2D materials based nanocomposites

Singh, Akash

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https://hdl.handle.net/2142/124121 Copy

Description

Title

Design and development of 2D materials based nanocomposites

Author(s)

Singh, Akash

Issue Date

2024-04-12

Director of Research (if dissertation) or Advisor (if thesis)

Li, Yumeng

Doctoral Committee Chair(s)

Li, Yumeng

Committee Member(s)

• Wang, Pingfeng
• Krishnan, Girish
• Cao, Qing

Department of Study

Industrial&Enterprise Sys Eng

Discipline

Systems & Entrepreneurial Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

2D materials, Machine Learning Potentials for Graphene, 2D materials nanocomposites, Templating effects of MoSe2

Abstract

In the forefront of materials science, 2D materials have emerged as a captivating research domain over the past two decades. Among these, graphene stands out as an exceptional 2D material with distinctive mechanical, thermal, and electrical properties, making it a critical component in applications spanning lightweight structural materials, versatile coatings, and flexible electronics. However, the high cost and complexity of experimental investigations have driven the adoption of computational simulations, particularly molecular dynamics (MD), to unveil the underlying microscopic origins of graphene’s unique properties. Yet, such simulations have yielded varying results, owing to the use of diverse empirical interatomic potentials used in these MD simulations. This dissertation aims to create an accurate interatomic potentials for 2D materials like graphene by using an artificial neural network (ANN)-based interatomic potential. These ANN based machine learning interatomic potentials for graphene are trained from the training data developed using first-principle based atomistic simulations. Machine learning potential (MLP) helps us to run high-fidelity Molecular Dynamics (MD) simulations approaching the accuracy of first principle simulations but with a fraction of computational cost. These MLP enables larger-scale simulations and extended timeframes, thereby accelerating the design, development and discovery of novel graphene/graphene based nanomaterials. Also, this dissertation aims to showcase MLP’s capability in estimating critical material properties of graphene, including coefficient of thermal expansion (CTE), lattice parameters, Young’s modulus, yield strength with comparable accuracy of that of experimental and first-principle calculations found from previous literatures. Remarkably, MLP’s capability in capturing dominant mechanisms governing the behaviour of CTE in graphene, including effects of changing lattice parameters and increasing/decreasing out-of-plane rippling with temperature, is a significant highlight of this dissertation. Furthermore, this MLP development method can be extended to other 2D materials, promising to expedite research on novel 2D materials and their unique atomic structures. Moving on to 2D materials-based nanocomposites, in today’s scientific and technological landscape, have assumed a position of significant importance. These hybrid material systems merge organic molecules with inorganic 2D materials, creating a new dimension of functional materials with varied applications i.e. materials for photovoltaics, electronics, nanotribology to aerospace applications. The interfaces between these 2D material and polymers serves as prototype material systems for studying confinement-induced phase transitions in 2D material based nanocomposites. Thorough understanding of dynamic and static behaviour of atoms in these interfaces at small length (nanometers) and time scales (nanoseconds) is critical as it material behaviour at this scale dictates overall material property of the resulting material system. Thus understanding the interfacial behaviour at atomic level will lead in the development of deliberately engineered 2D material and polymer based nanocomposites. But till date, the complexities of experimental testing at these small length and time scales as well as theoretical modeling have hindered a comprehensive understanding of these hetero-interfaces and thereby our ability to use these materials for practical purposes. To address this issues, this dissertation aims to understand the behaviour of 2D material and polymer at these interfaces using molecular dynamics (MD) simulations. By conducting MD simulations we focus on the assembly of polyethylene chains on surface of two dimensional MoSe2 sheet (which serves as a representative material system in this study to analyse the behaviour of 2D material based nanocomposites). All-atom models were created to simulate the dynamic assembly of n-pentacosane chains, which serves as a proxy for polyethylene in this study, on the surface of two dimensional MoSe2 sheet. This study reveals that polyethylene molecules starts crystallizing from 2D MoSe2-polyethylene interface and the crystallization growth front (plane of crystallized polymer chains) moves quickly towards the bulk polyethylene chains starting from the 2D material-polymer interface. At equilibrium, the directional registry of polyethylene chains on the 2D material surface happens through the interplay of free energy of the surface, adhesive interfacial interactions, conformational entropy, and the presence of substrate corrugation. The results suggests the potential of 2D materials, such as MoSe2, as a template for creating 2D material-polymer nanocomposites with specific crystallization orientations creating deliberate anisotropy and thereby resulting in a material system with tunable material properties.

Graduation Semester

2024-05

Type of Resource

Thesis

Copyright and License Information

Copyright 2024 Akash Singh

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