Non-covalently modified graphene sheets by imidazolium ionic liquids for multifunctional polymer nanocomposites

Abstract

Chemical reduction of graphite oxide (GO) to produce graphene nanosheets often results in irreversible agglomeration and precipitation. Herein, stable well-dispersed graphene sheets in solvents were obtained by simultaneous functionalization and reduction of GO under alkaline conditions, in the presence of sodium borohydride and imidazolium ionic liquids (Imi-ILs) containing two vinyl-benzyl groups. In this case, positively charged imidazolium groups of Imi-ILs underwent ion-exchange with negatively charged GO sheets and were linked to their edges, while Imi-ILs were non-covalently attached onto the large surfaces of graphene through p-p and/or cation-p stacking interactions. The vinyl-benzyl reactive sites were then copolymerized in situ with methyl methacrylate to fabricate graphene/poly(methyl methacrylate) (PMMA) composites. Functionalized graphene sheets were uniformly dispersed in the PMMA matrix and contributed to large increases in storage modulus (+58.3%) and glass transition temperature (+19.2 C) at 2.08 vol.% loading. High electrical conductivity was also achieved at graphene loading levels beyond 1 vol.% (ca. 2.55 Sm À1 ) with a low percolation threshold (0.25 vol.%) for the composites. Hence, a general methodology which facilitates the development of a multifunctional advanced material has been successfully established. This can be extended to other vinyl polymer-based composites containing graphene.

Developing highly conducting and mechanically durable styrene butadiene rubber composites with tailored microstructural properties by a green approach using ionic liquid modified MWCNTs

“…to improve their dispersion in polymer matrix, which will enhance the overall performance of the nanocomposites. [7][8][9][10] Among various nano-llers, CNTs modied by using ionic liquid can be used as potential reinforcing ller in various polymer matrixes which include elastomers, thermoplastics, thermosets and polyamides.…”

Progress in Imidazolium Ionic Liquids Assisted Fabrication of Carbon Nanotube and Graphene Polymer Composites

“…Recently, Han et al [61] have reported that graphene sheets are stably dispersed in an Imi-IL of 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF 6 ) with the help of poly(1-vinyl-3-butylimidazolium chloride) [poly(VbimCl)]. More recently, we have shown that Imi-ILs functionalized graphene sheets are homogenously embedded in the poly(methyl methacrylate) (PMMA) matrix and thus contribute to high electrical conductivity, low percolation threshold and large increases in storage modulus, glass transition temperature (T g ) and thermal stability compared to PMMA [62]. Over the past decade, the Imi-ILs assisted fabrication of polymer composites with CNTs and graphene has triggered an increasing attention [63]; however, a comprehensive review is still absent from the literatures.…”

“…However, bulk graphene sheets from RGO tend to restack as a graphite-like structure and show low dispersion in various solvents and polymers. Recently, we have reported a novel method to fabricate graphene/PMMA composites [62]. Initially, the functionalized graphene sheets were produced by chemical reduction of GO with NaBH 4 in the presence of NaOH and 1,6-bis[3-(vinyl benzyl)imidazolium-1-yl]hexane chloride (VbimBr) (Figure 2a).…”

The effect of varying carboxylic-group content in reduced graphene oxides on the anticorrosive properties of PMMA/reduced graphene oxide composites

“…One active field for PMMA application is the incorporation of nanomaterials. Over the past decade, many reports have been published on the addition of functionalized graphene sheets (FGSs) to PMMA to impart a variety of improved physical properties [13][14][15][16][17][18][19][20][21]. Villar-Rodil et al [16] prepared chemically reduced graphene/ PMMA by free radical solution-polymerization of methyl methacrylate (MMA) in the presence of exfoliated graphene oxide (GO).…”

“…As a result, the glass transition temperature shifted by over 15°C with graphene loadings as low as 0.05 wt%, and the elastic modulus increased by 28% at just 1 wt% loading. Jang et al [18] prepared conductive composites of PS/PMMA blends filled with octadecylamine-functionalized graphene (GE-ODA) and studied the electrical properties. Their results imply that the incorporation of GE-ODA into immiscible polymer blends is an efficient means of improving the electrical properties.…”