Tuning the Mechanical and Adhesion Properties of Carbon Nanotubes Using Aligned Cellulose Wrap (Cellulose Nanotube): A Molecular Dynamics Study.

Shishehbor Shishehbor,Pouranian Pouranian

doi:10.3390/nano10010154

Shishehbor Shishehbor, Pouranian Pouranian

Open Access

https://doi.org/10.3390/nano10010154

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Abstract

Improving the adhesion properties of carbon nanotubes (CNTs) at the molecular scale can significantly enhance dispersion of CNT fibers in polymer matrix and unleash the dormant extraordinary mechanical properties of CNTs in CNT-polymer nanocomposites. Inspired by the outstanding adhesion, dispersion, mechanical, and surface functionalization properties of crystalline nanocellulose (CNC), this paper studies the mechanical and adhesion properties of CNT wrapped by aligned cellulose chains around CNT using molecular dynamic simulations. The strength, elastic modulus, and toughness of CNT-cellulose fiber for different cellulose contents are obtained from tensile and compression tests. Additionally, the effect of adding cellulose on the surface energy, interfacial shear modulus, and strength is evaluated. The result shows that even adding a single layer cellulose wrap (≈55% content) significantly decreases the mechanical properties, however, it also dramatically enhances the adhesion energy, interfacial shear strength, and modulus. Adding more cellulose layers, subsequently, deceases and increases mechanical properties and adhesion properties, respectively. In addition, analysis of nanopapers of pristine CNT, pristine CNC, and CNT-wrapped cellulose reveals that CNT-wrapped cellulose nanopapers are strong, stiff, and tough, while for CNT and CNC either strength or toughness is compromised. This research shows that cellulose wraps provide CNT fibers with tunable mechanical properties and adhesion energy that could yield strong and tough materials due to the excellent mechanical properties of CNT and active surface and hydrogen bonding of cellulose.

Highlights

Engineering strong and tough materials has been the demand of many industries, such as automobile and aerospace, in the past decades
Significant stress transfer and improvement in the mechanical properties of carbon nanotubes (CNTs)-polymer nanocomposite were reported by wrapping poly(methyl methacrylate) (PMMA)-around CNT [13]
Due to (1) high mechanical properties and high surface energy of cellulose, (2) positive previous results in the literature on the effect of aligned polymer chains on CNT surface, (3) inspired by the structure of crystalline nanocellulose (CNC), where aligned cellulose chains are packed together through inter- and intra-hydrogen bonding, and (4) theoretical study on the stability and self-assembly of cellulose nanotube; wrapping single walled and multiwalled cellulose nanotube around CNT could result in stable fibers with much better functionality, and tunable mechanical properties that will be evaluated in this paper by molecular dynamics (MD) simulations

Summary

Introduction

Engineering strong and tough materials has been the demand of many industries, such as automobile and aerospace, in the past decades. Due to (1) high mechanical properties and high surface energy of cellulose, (2) positive previous results in the literature on the effect of aligned polymer chains on CNT surface, (3) inspired by the structure of CNC, where aligned cellulose chains are packed together through inter- and intra-hydrogen bonding, and (4) theoretical study on the stability and self-assembly of cellulose nanotube; wrapping single walled and multiwalled cellulose nanotube (aligned cellulose fibers in circular form) around CNT could result in stable fibers with much better functionality, and tunable mechanical properties that will be evaluated in this paper by MD simulations. We surmise that CNT-wrapped cellulose fibers that incorporate high strength and stiffness of CNT with high surface energy of CNC could yield strong, stiff, and tough nanopapers. The aim of this paper is to evaluate (1) the effect of adding aligned cellulose wrap around CNT on the mechanical and adhesion properties of CNT and (2) how these properties affect the strength, stiffness, and toughness of nanomaterials made by CNT-wrapped cellulose (for example, a nanopaper of CNT-wrapped cellulose)

CNC and CNT Wrapped by Cellulose

Findings

Single and Multilayer Cellulose Wrap