Abstract
We report on the grafting of poly(methyl methacrylate) (PMMA) onto the surface of high-density functionalized graphene oxides (GO) through controlled radical polymerization (CRP). To increase the density of surface grafting, GO was first diazotized (DGO), followed by esterification with 2-bromoisobutyryl bromide, which resulted in an atom transfer radical polymerization (ATRP) initiator-functionalized DGO-Br. The functionalized DGO-Br was characterized by X-ray photoelectron spectroscopy (XPS), Raman, and XRD patterns. PMMA chains were then grafted onto the DGO-Br surface through a ‘grafting from’ technique using ATRP. Gel permeation chromatography (GPC) results revealed that polymerization of methyl methacrylate (MMA) follows CRP. Thermal studies show that the resulting graphene-PMMA nanocomposites have higher thermal stability and glass transition temperatures (Tg) than those of pristine PMMA.
Highlights
The discovery of two-dimensional (2D) sp2 hybridized graphene sheets by Novoselov [1] in 2004 has received much attention due to their extraordinary electrical, thermal, and mechanical properties [1,2,3,4,5]
We focused on the functionalization of graphene oxides (GO) and highs-density grafting of poly(methyl methacrylate) (PMMA) chains onto its surface through an in situ ‘grafting from’ technique using atom transfer radical polymerization (ATRP)
differential scanning calorimetry (DSC) and Thermogravimetric analysis (TGA) studies show that the graphene-PMMA nanocomposites exhibited higher Tg and higher thermal stability compared to pristine PMMA polymers
Summary
The discovery of two-dimensional (2D) sp hybridized graphene sheets by Novoselov [1] in 2004 has received much attention due to their extraordinary electrical, thermal, and mechanical properties [1,2,3,4,5]. Efforts to enhance the end properties of graphene-polymer nanocomposites using surface polymerization through in situ ‘grafting to’ and ‘grafting from’ techniques have been reported [11,12]. Ramanathan et al reported an extraordinary shift in glass transition temperature (Tg), modulus, ultimate strength, and thermal stability for poly (acrylonitrile) and poly(methyl methacrylate) using very low levels of functionalized graphene sheets [13]. In situ emulsion polymerization of methyl methacrylate (MMA) was carried out by Kuila et al using graphene as a reinforcing filer, which enhanced the storage moduli, Tg, and thermal stability of the resulting nanocomposites [14]
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