Functionalization and Dispersion of Carbon Nanomaterials Using an Environmentally Friendly Ultrasonicated Ozonolysis Process

Eudora S. Y. Yeo; Gary I. Mathys; Narelle Brack; Erik T. Thostenson; Andrew N. Rider

doi:10.3791/55614

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Method Article

Functionalization and Dispersion of Carbon Nanomaterials Using an Environmentally Friendly Ultrasonicated Ozonolysis Process

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DOI:

10.3791/55614

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May 30th, 2017

Eudora S. Y. Yeo¹ , Gary I. Mathys² , Narelle Brack³ , Erik T. Thostenson⁴^,⁵^,⁶ , Andrew N. Rider¹

¹Aerospace Division, Defence Science and Technology Group, ²Maritime Division, Defence Science and Technology Group, ³Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, ⁴Department of Mechanical Engineering, University of Delaware, ⁵Department of Materials Science and Engineering, University of Delaware, ⁶Center for Composite Materials, University of Delaware

Summary

Here, a novel method for the functionalization and stable dispersion of carbon nanomaterials in aqueous environments is described. Ozone is injected directly into an aqueous dispersion of carbon nanomaterial that is continuously recirculated through a high-powered ultrasonic cell.

Abstract

Functionalization of carbon nanomaterials is often a critical step that facilitates their integration into larger material systems and devices. In the as-received form, carbon nanomaterials, such as carbon nanotubes (CNTs) or graphene nanoplatelets (GNPs), may contain large agglomerates. Both agglomerates and impurities will diminish the benefits of the unique electrical and mechanical properties offered when CNTs or GNPs are incorporated into polymers or composite material systems. Whilst a variety of methods exist to functionalize carbon nanomaterials and to create stable dispersions, many the processes use harsh chemicals, organic solvents, or surfactants, which are environmentally unfriendly and may increase the processing burden when isolating the nanomaterials for subsequent use. The current research details the use of an alternative, environmentally friendly technique for functionalizing CNTs and GNPs. It produces stable, aqueous dispersions free of harmful chemicals. Both CNTs and GNPs can be added to water at concentrations up to 5 g/L and can be recirculated through a high-powered ultrasonic cell. The simultaneous injection of ozone into the cell progressively oxidizes the carbon nanomaterials, and the combined ultrasonication breaks down agglomerates and immediately exposes fresh material for functionalization. The prepared dispersions are ideally suited for the deposition of thin films onto solid substrates using electrophoretic deposition (EPD). CNTs and GNPs from the aqueous dispersions can be readily used to coat carbon- and glass-reinforcing fibers using EPD for the preparation of hierarchical composite materials.

Introduction

The use of carbon nanomaterials to modify polymeric and composite systems has seen intensive research interest over the past 20 years. Recent reviews on both the use of carbon nanotubes¹ (CNTs) and graphene nanoplatelets² (GNPs) provide an indication of the breadth of research. The high specific stiffness and strength of CNTs and GNPs, as well as their high intrinsic electrical conductivity, make the materials ideally suited for incorporation into polymeric systems to enhance both the mechanical and electrical performance of the nanocomposite materials. CNTs and GNPs have also been used for the development of hierarchica....