Vapor Phase Modification for Selective Enrichment of Grafted Styrene/Acrylonitrile onto Carbon Nanotubes Via ATRP

Maryam Azadbakht,Ali Vahidifar,Tizazu H Mekonnen,Mehdi Salami-Kalajahi,Elnaz Esmizadeh

doi:10.3390/pr9030459

Abstract

Nitric acid vapor phase oxidation of multi-walled carbon nanotubes (MWCNTs) was proposed as a promising technique to fabricate poly styrene-co-acrylonitrile (SAN)-grafted-CNTs via atom transfer radical polymerization (ATRP). The in-situ ATRP grafting approach was successfully employed to graft polystyrene (PS), SAN and polyacrylonitrile (PAN), onto the convex surfaces of pristine MWCNTs (PCNT) and acid-functionalized MWCNTs (FCNT). Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H-NMR), and thermogravimetric analysis (TGA) confirmed the effectiveness of the modification via the ATRP grafting approach. The molar composition of acrylonitrile in the synthesized copolymer on the surface of CNTs for an FCNTs was calculated to be about 80% and 67.5% by 1H-NMR and TGA respectively, whereas the value is lower for PCNTs. Morphological studies showed that SAN-grafted FCNTs exhibit rougher surface morphology compared to the SAN-grafted PCNTs. Moreover, the higher diameter of the FCNTs indicated the higher polymer content, which was coated onto CNTs functionalized by vapor-phase oxidation. Therefore, the vapor phase oxidation strategy employed in this study could be utilized as a general method to prepare CNTs which can serve as an ATRP macroinitiator for the fabrication of various polymer grafted CNTs.

Highlights

Carbon nanotubes (CNTs) are categorized among the most impressive recent discoveries in chemistry and materials science [1,2]
The functionalization and surface modification of CNTs are widely accepted and promising measures to improve their dispersion in solvents and enhance their compatibility with polymers by tailoring their structure and surface properties, favoring the fabrication of CNT-based composites [8]
The atom transfer radical polymerization (ATRP) of styrene and acrylonitrile monomers on the surface of CNTs was performed in THF at 90 °C with CuBr as a catalyst and EBiB-multi-walled carbon nanotubes (MWCNTs) as an initiator

Summary

Introduction

Carbon nanotubes (CNTs) are categorized among the most impressive recent discoveries in chemistry and materials science [1,2]. CNTs have raised much enthusiasm during the latest years due to their intrinsic extraordinary electrical and mechanical properties [3]. Transferring their properties into bulk and real-life materials is restricted by their insolubility in most solvents [4,5] and their low dispersibility in polymer matrices [6,7]. CNTs graphitic surface [9,10] Such oxygen-containing groups can help to diversify further tailoring of CNTs and change their performance in a wide range of materials [9,10]

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Conclusion