Synthesis of Graphene Nanofluids with Controllable Flake Size Distributions

Summary

A method for synthesizing graphene nanofluids with controllable flake size distributions is presented.

Abstract

A method for synthesizing graphene nanofluids with controllable flake size distributions is presented. Graphene nanoflakes can be obtained by the exfoliation of graphite in the liquid phase, and the exfoliation time is used to control the lower limits of the graphene nanoflake size distributions. Centrifugation is successfully used to control the upper limits of the nanoparticle size distributions. The objective of this work is to combine exfoliation and centrifugation to control the graphene nanoflake size distributions in the resulting suspensions.

Introduction

Traditional methods used to synthesize graphene nanofluids often use sonication to disperse graphene powder¹ in fluids, and sonication has been proven to change the size distribution of graphene nanoparticles². Since the thermal conductivity of graphene depends on the flake length^3,4, the synthesis of graphene nanofluids with controllable flake size distributions is vital to heat-transfer applications. Controlled centrifugation has been successfully applied to liquid exfoliated graphene dispersions to separate suspensions into fractions with different mean flake ....

Protocol

1. Exfoliation of graphite in a liquid phase

1. Preparation of reagents
   1. In a dry clean flat-bottom flask, add 20 g of polyvinyl alcohol (PVA), and then add 1,000 mL of distilled water.
      NOTE: If the suspension was not processed to satisfaction, the step could be repeated to obtain an additional suspension.
   2. Gently swirl the flask until the PVA fully dissolves.
      CAUTION: PVA is harmful to humans; thus, protective gloves and surgical masks should be used.
   3. Add 50 .......

Discussion

We have proposed a methodology for synthesizing graphene nanofluids with controllable flake size distributions. The method combines two procedures: exfoliation and centrifugation. Exfoliation controls the lower size limit of the nanoparticles, and centrifugation controls the upper size limit of the nanoparticles.

Although we employed liquid-phase exfoliation of graphite to produce graphene nanoparticles, the following modifications to the protocol should be considered. Additional exfoliation p.......

Materials

Name	Company	Catalog Number	Comments
Beaker	China Jiangsu Mingtai Education Equipments Co., Ltd.	500 mL
Beaker	China Jiangsu Mingtai Education Equipments Co., Ltd.	5000 mL
Deionized water	Guangzhou Yafei Water Treatment Equipment Co., Ltd.		analytical grade
Electronic balance	Shanghai Puchun Co., Ltd.	JEa10001
Filter membrane	China Tianjin Jinteng Experiment Equipments Co., Ltd.	0.2 micron
Graphite powder	Tianjin Dengke chemical reagent Co., Ltd.		analytical grade
Hand gloves	China Jiangsu Mingtai Education Equipments Co., Ltd.
Laboratory shear mixer	Shanghai Specimen and Model Factory	jrj-300
Long neck flat bottom flask	China Jiangsu Mingtai Education Equipments Co., Ltd.	1000 ml
Nanoparticle analyzer	HORIBA, Ltd.	SZ-100Z
PVA	Shanghai Yingjia Industrial Development Co., Ltd.	1788	analytical grade
Raman spectrophotometer	HORIBA, Ltd.	Horiba LabRam 2
Scanning electron microscope	Zeiss Co., Ltd.	LEO1530VP	SEM
Surgical mask	China Jiangsu Mingtai Education Equipments Co., Ltd.	for one-time use
Thermal Gravimetric Analyzer	German NETZSCH Co., Ltd.	NETZSCH TG 209 F1 Libra	TGA analysis
Transmission electron microscope	Japan Electron Optics Laboratory Co., Ltd.	JEM-1400plus	TEM
UV-Vis spectrophotometer	Agilent Technologies, Inc.+BB2:B18	Varian Cary 60