Enhancing the properties of polymer nanocomposites by inducing a stable dispersion of carbon nanotubes through polymer wrapping

Author: Muthuraman Namasivayam

Namasivayam, Muthuraman, 2020 Enhancing the properties of polymer nanocomposites by inducing a stable dispersion of carbon nanotubes through polymer wrapping, Flinders University, College of Science and Engineering

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Polymer matrices have some interesting advantages to offer such as being light weight, cost effective and many more. Introducing a conductive filler like carbon nanotubes (CNTs) can enhance the properties of the polymer composite for various industrial applications. Although, carbon nanotubes act as an effective filler, aggregate formation in 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 and can provide stable dispersions in organic solvents. Covalent functionalization has proven effective in terms of stability but the chances of causing damage to the CNTs and altering their intrinsic properties are high. Non-covalent functionalization of nanotubes is an excellent way to overcome aggregate formation and achieve a homogeneous dispersion of nanotubes in the polymer matrix without disrupting the intrinsic characteristics of the nanotubes. In this work, analysis of the physical properties of a non-covalently functionalized carbon nanotube/PVDF composites was undertaken. The amount of CNTs and Polyvinylidene fluoride polymer was essentially kept constant, with only the concentration of the functionalization polymer varied.

The first component of this work concentrated on analysis of the effect of the molecular weight of water-soluble polymer (Polyvinylpyrrolidone - PVP) for non-covalent functionalization of carbon nanotubes. A study with four different molecular weights of PVP was conducted. This study discusses the change in polymer wrapping behaviour of different molecular weight with respect to the aspect ratio of nanotubes, amount of nanotubes and structure of nanotubes. The second aspect concentrated on the effect of the structure of the wrapping polymer (Polyvinylpyrrolidone - PVP versus Poly(4-vinylpyridine) – P4VP) on non-covalent functionalization. A comparative study based on polymers of two different structures but of similar molecular weight was conducted. This study discusses the relation between the polymer wrapping pattern of two different polymer structures and the structure of nanotubes. A final study on non-covalently functionalized cationic polymer (Polyethyleneimine- PEI) in the CNT/PVDF composite was conducted with two different molecular weights of PEI. This is a confirmation study to ascertain the polymer wrapping behaviour of two different molecular weights and its relationship with the structure of nanotube.

Keywords: Polymer nanocomposite, Non-covalent functionalization, Polymer wrapping, Polyvinylpyrrolidone, Poly(4-vinylpyridine), Polyethyleneimine, MWNT, P3-SWNT, AP-SWNT.

Subject: Nanotechnology thesis

Thesis type: Doctor of Philosophy
Completed: 2020
School: College of Science and Engineering
Supervisor: Joe Shapter