1. Exfoliation and Utilization of at By : Anton and Diana

2. Table of Contents IntroductionBackground Methods Sonication Factors Result Measurement Techniques Thermal Management Research and Future WorkSummary Exfoliation and Utilization of h-BN Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 2

3. 3 Introduction

4. -As, 3D chip architecture increases in complexity there is increase in heat flux -Current polymer encapsulation does not have sufficient K eff Exfoliation and Utilization of h-BN Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 4

5. Introduction Hexagonal boron nitride (h-BN) : Analog to graphene Large band gap of ~ 5.5eV High theoretical thermal conductivity Difficult to exfoliate Exfoliation and Utilization of h-BN Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 5

6. Introduction Exfoliation and Utilization of h-BN Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 6 Exfoliation Specifically Focused On Liquid Phase Sonication

7. 7 Background

8. 8 - Methods -

9. Methods Exfoliation and Utilization of h-BN Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 9 Mechanical Cleavage Ball Milling Chemical Functionalization Liquid Phase Sonication

10. Methods Exfoliation and Utilization of h-BN Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 10 Mechanical Cleavage Ball Milling Chemical Functionalization Liquid Phase Sonication

11. 11 Background - Sonication Factors -

12. Factors SolventsSonication settingsSize of Solutes Exfoliation and Utilization of h-BN Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 12

13. Factors SolventsSonication settingsSize of Solutes Exfoliation and Utilization of h-BN Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 13

14. Factors - Solvents Exfoliation and Utilization of h-BN Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 14 Effective Solvent Low enthalpy of system Low energy for sonication Matching surface energy InexpensiveEco friendly No foreign materials produced

15. Water as solvent -H-BN normally hydrophobic in water -Boron- nitrogen bonds near defect sites make exfoliation easier -Boron edges formed hydroxyl groups under hydrolysis Exfoliation and Utilization of h-BN Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 15

16. Solvent Promoting Chemical Functionalization -Polymer—poly (sodium 4-styrenesulfonate) (PSS) used as a dispersant and functionalization agent -Improved the separation of layers from h-BN structure Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 16 Exfoliation and Utilization of h-BN

17. Isopropyl Alcohol(IPA) solution as solvent -IPA has matching surface energy to h-BN(44- 65 mJ/m^2) -Ammonia water also has matching surface energy of ~ 57 mJ/m^2 -Create solution of IPA: ammonia solution of ~3:2 -Boron atoms temporarily act like lewis acids and are susceptible to attack from amines Exfoliation and Utilization of h-BN Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 17

18. Factors SolventsSonication settingsSize of Solutes Exfoliation and Utilization of h-BN Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 18

19. Sonication Settings Exfoliation and Utilization of h-BN Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 19 Uses sound wave with a preset wavelength to agitate particles in a solution

20. Factors SolventsSonication settingsSize of Solutes Exfoliation and Utilization of h-BN Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 20

21. Size of Solutes Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 21 Sonication Sound Wavelength Sizes of pristine h-BN → Higher Exfoliation yield can be achieved Exfoliation and Utilization of h-BN

22. 22 Background - Result Measurement -

23. Result Management Exfoliation and Utilization of h-BN Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 23 Infrared Thermal Imaging Optical Absorption Raman Spectroscopy X-ray diffraction

24. Infrared Thermal Imaging -Model developed by Georgia Institute of Technology is commonly used -Measures the thermal Resistance & Thermal Conductivity of the sample Exfoliation and Utilization of h-BN Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 24

25. Optical Absorption Band Gap: the bulk h-BN < an isolated h-BNNS Exfoliation ↑ the absorptivity of the dispersion Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 25 Exfoliation and Utilization of h-BN

26. Raman Spectroscopy Helps identify the number of layers of h- BN Mono-layers: slightly upward Bi-layers: downward in peak position Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 26 Exfoliation and Utilization of h-BN

27. X-ray Diffraction (XRD) Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 27 Exfoliation and Utilization of h-BN

28. 28 Background - Thermal Management -

29. Thermal Management -Ceramics only use the vibration of phonons to transfer heat -Issue with using ceramic fillers is you need high filler loading (>50 wt%) -H-BN nanosheets provide a way to increase thermal conductivity substantially Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 29 Exfoliation and Utilization of h-BN

30. Thermal Management Thermal Enhancement factor(TEF) of a h-BN/ epoxy composite was observed using: (k composite - k epoxy )/ k epoxy * 100%, k refers to the thermal conductivity Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 30 Exfoliation and Utilization of h-BN

31. Thermal Management -With increase in filler loading, viscosity increases making it more difficult to process -Coefficient of thermal expansion decreases and glass transition temperature slightly decreases Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 31 Exfoliation and Utilization of h-BN

32. Thermal Management -Theoretical calculations show thermal conductivity should increase as amount of layers decreases -But the experimental data showed this was not the case -Thickness of sheets proved to be more important as when the sheets are thinner they are less thermally conductive Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 32 Exfoliation and Utilization of h-BN

33. 33 Research and Future Work

34. Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 34 Exfoliation and Utilization of h-BN

35. Research and Future Work Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 35 Exfoliation and Utilization of h-BN

36. Research and Future Work Multifunctional Materials | Micro-and-Nanostructuring Laboratory Slide 36 Exfoliation and Utilization of h-BN

37. 37 Summary

38. Questions/Comments? 38 Exfoliation and Utilization of h-BN