In-situ interfacial compatibilization via edge-sulfurated few layer graphene during the formation of crosslinked graphene-rubber nanocomposites

Sangeeth Krishnan,Akhil Das,Swaminathan Sivaram,Lakshminarayanan Ragupathy,Krithika Ganesan,Prabha Vadivelu,Maya M.G,Suja Bhargavan

doi:10.1038/s41598-022-08071-w

Abstract

Herein, we report various physico-chemical approaches to probe the nature of the interface between few layers graphene (FLG) and carboxylated nitrile rubber (XNBR) nanocomposites prepared through efficient blending of XNBR latex with an aqueous dispersion of FLG. The extent of physical interaction between FLG and XNBR was investigated using Lorentz–Park and Cunneen–Russell models. The chemical interface between FLG and sulfur crosslinked XNBR was studied using model reactions between sulfur and graphene in presence of zinc 2-mercaptobenzothiazole (ZMBT). We propose that an edge sulfurated FLG is formed, which could chemically bond with XNBR during the vulcanization process. Density Functional Theory (DFT) was employed to unravel the mechanistic insights, which support this hypothesis and suggest a kinetically favorable sulfuration of both XNBR and FLG. The formation of a chemical bond between edge-FLG and XNBR through the proposed intermediacy of sulfurated FLG leads to the observed improvement in mechanical properties of the nanocomposites.

Highlights

We report various physico-chemical approaches to probe the nature of the interface between few layers graphene (FLG) and carboxylated nitrile rubber (XNBR) nanocomposites prepared through efficient blending of XNBR latex with an aqueous dispersion of FLG
The presence of defect-free FLG was confirmed by Transmission Electron Microscopy (TEM), Raman Spectroscopy and X-ray Photoelectron Spectroscopy (XPS)
It is believed that the chemical functionalities present in graphene oxide (GO)/reduced GO (rGO) react with the functionalities on the XNBR leading to a chemical bond between graphene and polymer, creating a strong polymer–graphene interface that leads to the observed improvement in properties

Summary

Introduction

We report various physico-chemical approaches to probe the nature of the interface between few layers graphene (FLG) and carboxylated nitrile rubber (XNBR) nanocomposites prepared through efficient blending of XNBR latex with an aqueous dispersion of FLG. The formation of a chemical bond between edge-FLG and XNBR through the proposed intermediacy of sulfurated FLG leads to the observed improvement in mechanical properties of the nanocomposites. Styrene-butadiene rubber (SBR)-graphene nanocomposite was prepared using modified GO with alkylamines[27], which significantly improved their interfacial interaction through sulfur and the double bond present in the alkylamines or through the use of orthoquinone-thiol c hemistry[28]. Model reactions were performed between FLG, S, ZMBT and ZnO (except XNBR) and the resultant product had been purified and characterized Based on these results and the computational studies using DFT, we propose a novel chemical hypothesis for the interaction between FLG and XNBR

Methods

Results

Conclusion