Carbon nanotubes (CNTs) have exceptional properties and are mass-producible at the ton scale as aggregated powders, but their difficulty in processing is a significant barrier to widespread use. Even after decades of research, there still isn’t a solvent for CNTs that is massively available, easily removable, and non-damaging. The need for an effective solvent highlights the impact of my discovery that cresols, a group of naturally occurring and mass-produced methylphenols, are unexpectedly effective solvents for CNTs. They can homogenize CNTs up to tens of weight percent, without additional dispersing agents or nanotube functionalization. The outstanding processability comes from cresols’ charge-transfer complexation capability between the phenolic hydroxyl groups and the aromatic surface of CNT, which separates CNTs and stabilize the solution. Since charge-transfer interactions are electrostatic in nature, the complexes are stable against solvents with low dielectric constants. When these solvents dilute dispersion of nanotubes in m-Cresol, the complexes stay stable and keeps m-cresol attracted to nanotubes’ aromatic surface. Affinity of m-cresol to CNT assists the initial disentanglement of nanotube aggregates, and complexed solvent molecules help to keep CNT stable in dispersion. In a good solvent, separated nanotubes become outstretched like dissolved polymer molecules. This nanotube mixture displays viscoelastic properties typical of polymer solutions. With increasing CNT concentrations, nanotube mixtures can continuously transition between dilute dispersions, thick pastes, free-standing gels, and kneadable, playdough-like materials. These four highly processible states are immediately usable for different processing techniques such as Langmuir-Blodgett film assembly, blade coating, air-spray coating, 3D printing, and sculpting. In addition to being a solvent for CNT, m-cresol demonstrates that simple phenols can process various conjugated carbon nanomaterials. This concept was demonstrated by dispersing CNT with the aid of either 3,4-xylenol or vanillin. m-Cresol also disperses Carbon black and graphite, and this shows that various carbon nanomaterials behave similarly in complexing with phenols. These proofs of concepts demonstrate that carbon nanomaterials can be made more accessible by using phenols as processing aids and adapting existing equipment to process these nanomaterials.

Creator

• Chiou, Kevin

DOI

• https://doi.org/10.21985/n2-mpy6-tf63

Subject

• Nanoscience

Language

• en

Alternate Identifier

• etdadmin_upload_742961
• http://dissertations.umi.com/northwestern:15105

Keyword

• Cresol
• Carbon Nanotube

Date created

• 2020-01-01

Resource type

• Dissertation

Rights statement

• In Copyright