A Comparative Study on the Role of Polyvinylpyrrolidone Molecular Weight on the Functionalization of Various Carbon Nanotubes and Their Composites.

Muthuraman Namasivayam,Joseph G Shapter,Mats R Andersson

doi:10.3390/polym13152447

Muthuraman Namasivayam, Joseph G Shapter + Show 1 more

Open Access

https://doi.org/10.3390/polym13152447

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Abstract

Polyvinylidene fluoride (PVDF) nanocomposites filled with polyvinylpyrrolidone (PVP) wrapped carbon nanotubes were prepared via a solution casting technique. The effect of the molecular weight (polymer chain length) of the PVP on the ability to wrap different nanotube structures and its impact towards nanotube dispersibility in the polymer matrix was explored. The study was conducted with PVP of four different molecular weights and nanotubes of three different structures. The composites that exhibit an effective nanotube dispersion lead to a nanotube network that facilitates improved thermal, electrical, and mechanical properties. It was observed that nanotubes of different structures exhibit stable dispersions in the polymer matrix though PVP functionalization of different molecular weights, but the key is achieving an effective nanotube dispersion at low PVP concentrations. This is observed in MWNT and AP-SWNT based composites with PVP of low molecular weight, leading to a thermal conductivity enhancement of 147% and 53%, respectively, while for P3-SWNT based composites, PVP of high molecular weight yields an enhancement of 25% in thermal conductivity compared to the non-functionalized CNT-PVDF composite.

Highlights

The field of polymer nanocomposites had been of interest for the past few decades, and there is an increasing demand for more advanced functional materials
Nanotubes of three different structures were non-covalently functionalized using polyvinylpyrrolidone polymers of different molecular weight towards the preparation of PVP@carbon nanotube (CNT)/Polyvinylidene fluoride (PVDF) composites at a range of PVP concentrations, and the thermal conductivity of each sample was measured
The measurement observed at 0 wt. % is the thermal conductivity of non-functionalized multi-walled nanotube (MWNT) or P3-SWNT or AP-SWNT/PVDF composite

Summary

Introduction

The field of polymer nanocomposites had been of interest for the past few decades, and there is an increasing demand for more advanced functional materials. Carbon nanotubes act as an effective filler, aggregate formation in the polymer matrix due to the high van der Waals interactions between the nanotubes is inevitable. Surface functionalization of nanotubes is the best approach to reduce the interaction between nanotubes while preserving the original morphology and conductivity of the nanotubes. This can provide stable dispersions in organic solvents. Non-covalent functionalization (polymer wrapping) of nanotubes is considered a highly effective way to overcome aggregate formation and achieve a homogeneous dispersion of nanotubes in the polymer matrix without disrupting the intrinsic characteristics of the nanotubes. The physical and mechanical properties of polymer nanocomposites can be influenced by both the molecular weight of the polymer and the structure of the nanotube filler

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