Role of Solvent Polarity on Dispersion Quality and Stability of Functionalized Carbon Nanotubes

Dhivakar Rajendran,Rajarajan Ramalingame,Anurag Adiraju,Hanen Nouri,Olfa Kanoun

doi:10.3390/jcs6010026

Dhivakar Rajendran, Rajarajan Ramalingame + Show 3 more

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https://doi.org/10.3390/jcs6010026

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Abstract

Dispersion of carbon nanotubes (CNT) in solvents and/or polymers is essential to reach the full potential of the CNTs in nanocomposite materials. Dispersion of CNTs is especially challenging due to the van-der-Waals attraction forces between the CNTs, which let them tend to re-bundle and/or re-aggregate. This paper presents a brief analysis of the quality and stability of functionalized multiwalled carbon nanotubes (fMWCNT) dispersion on polar solvents. A comparative study of functionalized CNT dispersion in water, methyl, and alcohol-based organic solvents has been carried out and the dispersion has been characterized by UV-VIS spectroscopy, electrochemical characterization such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Visual analysis of the dispersion has been investigated for up to 14 days to assess the dispersion’s stability. Based on the material characterization, it was observed that the degree of affinity fMWCNT with -COOH group highly depends on the polarity of the solvent, where the higher the polarity, the better the interaction of fMWCNT with solvents.

Highlights

Carbon nanotubes (CNTs) are among the most promising nanofillers in the field of nanocomposite sensors due to their high aspect ratio, excellent mechanical properties, good electrical and thermal conductivity, which are essential properties for many applications [1].It was reported that carbon nanotubes (CNT) can enhance the photo-catalysis perfomance of ZnO and TiO2 due to its unique electronic and adsorption properties [2,3,4]
The stronger hydrogen bonding between the functional groups on the functionalized multiwalled carbon nanotubes (fMWCNT) wall and solvent enables the fMWCNT in the exfoliated state
The quality and stability of dispersion have been characterized by evaluating the absorption of UV-light by individual fMWCNT in the dispersion, where high absorbance is better the dispersion quality, and more minor variation in absorbance over a certain time shows the stability of the dispersion

Summary

Introduction

Carbon nanotubes (CNTs) are among the most promising nanofillers in the field of nanocomposite sensors due to their high aspect ratio, excellent mechanical properties, good electrical and thermal conductivity, which are essential properties for many applications [1].It was reported that CNTs can enhance the photo-catalysis perfomance of ZnO and TiO2 due to its unique electronic and adsorption properties [2,3,4]. Many works have been investigating how to achieve the effective dispersion of CNT in solvents and polymers. It remains a very challenging task given the entanglement as well as breakage of CNTs that occurs during processing in addition to the poor interfacial interaction between the CNTs and the dispersing medium [6]. When the surface of a CNT suffers from oxidation, chemical elements are adsorbed, forming functional groups. These functional groups interact with solvents via polar-polar interaction, which results in the formation of hydrogen bonds, so that the CNTs to repel each other, preventing the formation of agglomerates [15].

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