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Integration of Graphene-based Multifunctional Stacked Composites

  • 김승일 (아주대학교 일반대학원)

초록/요약

Two-dimensional (2D) materials serve as reinforcements that enhance the properties of conventional bulk materials. Despite negligible contribution to volume and weight, their atomic-level thickness allows them to significantly improve the properties of matrix. Particularly, semi-infinite single-atomic-layer graphene is an ideal reinforcement capable of simultaneously improving the mechanical, electrical, thermal, and optical properties of the composite. In this dissertation, I will discuss methods for integration of composites with graphene aligned within the matrix and their multifunctional properties. Our approach begins with the synthesis of graphene with various substrates using a chemical vapor deposition (CVD) method. The synthesized large-area graphene with high aspect ratio can be transferred into freestanding films through a support layer. Oxide-based support layers enable the graphene-oxide composites themselves, and the optical properties of graphene- oxide composites were further examined through interfacial engineering. However, integration of composites by the transfer process faces limitations in fabricating large-scale stacked composites. To overcome these limitations, we develop a float- stacking strategy, enabling continuous stacking by rolling suspended films on water. PMMA, used as the polymer matrix, and graphene nanomembranes float at the water-air interface, relying solely on the surface energy of water. Graphene-PMMA nanomembranes are rolled onto cylindrical rollers without friction. During the stacking process, meniscus effects at the interface between the graphene-PMMA surface and water induce continuous web tension on the nanomembrane, effectively suppressing structural defects. This process ensures uniform alignment of graphene within the polymer matrix, with precise control over spacing. The composites fabricated with multifunctional graphene exhibited improved properties, including enhanced mechanical, thermal, electrical, and electromagnetic shielding performance. Lastly, this dissertation explores the extension of graphene-based composites. Copper, known for its high electrical properties, was used as the metal matrix to fabricate graphene-metal composites and engineer their nanostructures for advanced applications. Rolled-up stacking produced cylindrical graphene- copper composites, which, due to their cylindrical geometry, can be transformed into cable through spiral cutting without structural discontinuity.

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목차

Chapter 1. Introduction 1
1-1 General Introduction of 2D materials 1
1-1-1 Brief overview of 2D materials 1
1-1-2 Graphene 5
1-2 Concept of Nanocomposite 7
1-3 Research objective and approach 11
Chapter 2. Literature Survey 13
2-1 Multifunctional of 2D materials 13
2-1-1 General Introduction 13
2-1-2 Mechanical and Thermal properties of 2D materials 15
2-1-3 Electrical properties of 2D materials 17
2-2 Preparation of 2D materials 19
2-2-1 General Introduction 19
2-2-2 Top-down method 21
2-2-3 Bottom-up method 24
2-3 Graphene-based Nanocomposites 26
2-3-1 General Introduction 26
2-3-2 Matrix in Nanocomposite 27
2-3-3 Fabrication method 32
2-3-4 Discontinuous and Continuous Graphene reinforcement 37
Chapter 3. Synthesis and Transfer Process for Large-Scale CVD- Graphene 40
3-1 Introduction 41
3-2 Experimental 45
3-3 Result and Discussion 49
3-3-1 Synthesis of Graphene on Cu and Ge substrate 49
3-3-2 Support layers for Graphene transfer 56
3-3-3 Photodetector based on Graphene Nanocomposite 78
3-4 Conclusion 93
Chapter 4. Multifunctional Graphene-Polymer Nanocomposite 96
4-1 Introduction 97
4-2 Experimental 102
4-3 Result and Discussion 109
4-3-1 Float-stacking strategy 109
4-3-2 Mechanical properties of the Graphene-PMMA laminate (GPL) 117
4-3-3 Reinforcing Mechanism of the aligned Graphene layers in GPL 130
4-3-4 Thermal properties of GPL 141
4-3-5 Electromagnetic interference shielding effectiveness (EMI SE) of the GPL 151
4-4 Conclusion 159
Chapter 5. Graphene-Metal Nanocomposite 161
5-1 Introduction 162
5-2 Experimental 165
5-3 Result and Discussion 168
5-3-1 Fabrication of Graphene-Metal Nanocomposite 168
5-3-2 Nanostructure engineering of Graphene-Metal Nanocomposite 175
5-3-3 Electrical properties in Graphene-Metal Nanocomposite 180
5-4 Conclusion 184
References 186
국문요약 212
List of publications 214

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