Excellent dispersion of MWCNTs in PEO polymer achieved through a simple and potentially cost-effective evaporation casting

Abstract

A simple, reliable and potentially cost-effective composite film casting procedure is presented using the evaporation of solvent (water) from a dilute mixture of multiwalled carbon nanotubes (MWCNTs) and polyethylene oxide (PEO) polymer. It is found that the fabrication method develops excellent dispersion of MWCNTs in PEO confirmed by morphology observations, final crystallinity of polymer (amorphous) and a lower percolation threshold (closer to theoretical value) as well as higher electrical conductivity. A film thickness prediction model is derived based upon the fact that final film thickness is mainly dependent upon the dimensions of the casting mold and the loading of the MWCNTs and polymer. This simple model provides important insight that the material loss and the actual density of the base polymer are critical factors making the current casting method truly cost effective and controlling final thickness.

Carbon Nanotube-Based Poly(ethylene oxide) Nanocomposites

“…There are several opposing observations reported in literature on PEO crystallization in the presence of MWNTs. Park et al found that MWNTs hinder PEO crystallization, and above 10 % nanotube loading the SAXS pattern does not show any lamellar reflection from PEO crystals [40]. Similarly, Abraham and coworkers reported $10 % decrease in PEO % crystallinity at $3-4 % MWNTs loading [122].…”

“…This indicates that beyond the percolation threshold, cluster effect is more pronounced than the individual nanoparticles' dispersion state. Park et al observed a percolation threshold between 1.0 and 2.0 vol% for MWNTs in PEO and summarized the percolation threshold for carbon nanotubes-PEO nanocomposites reported by different research groups [40]. Finally, while many of the previous studies have shown that electrical and geometrical percolations are coincident [53,54] or that the value for the electrical percolation threshold is somewhat greater than the corresponding geometrical percolation [55,56], it is anticipated [57] and observed for multiwalled carbon nanotube-polymer composites that the connectivity (i.e., electrical) percolation precedes the rigidity (i.e., geometrical) percolation [58].…”

“…The surfactant molecules de-rope the nanotube bundles and PEO chains complex around lithium ions to develop well-homogenized nanocomposites. Following the same route [33], Park and coworkers dispersed MWNTs in PEO using a costeffective evaporation (using DI water, a good solvent for PEO chains) casting technique which is suitable for large-scale applications [40]. Besides simplicity, this dispersion pathway is technologically important as lithium salts, for their low lattice energy, high coordination number, and crown-ether formation capability, are often used in solid electrolytes which make the PEO chains amorphous and improve room temperature ionic conductivity [12,41].…”

“…Vaisman and coworkers developed a MWNTs dispersion state quantification in PEO using particle size analysis (based on dynamic light scattering (DLS)), while visual characterization was based on optical and electron microscopy [49]. Park and coworkers used field emission scanning electron microscopy (FE-SEM) as well as ex situ small-angle X-ray scattering to characterize MWNTs dispersion state in PEO matrix [40]. It is essential to characterize the dispersion state of nanotubes in polymer matrix quantitatively.…”

A passively harmonically mode‐locked soliton erbium‐doped fiber laser with low pumping threshold using a single‐walled carbon nanotubes

“…It is implemented by mixing the nanotubes with water soluble polymer and the evaporation process is either using low temperature ovens or simply by letting it dry at room temperature . Recently, Park et al demonstrated multiwalled carbon nanotubes—polyethylene oxide (PEO) composite film using evaporation technique that makes use of the low melting temperature of PEO.…”