Ultrasound-induced exfoliation of graphene in 1,4-butanediol diglycidyl ether monomer: a promising free-solvent route to epoxy-based nanocomposites

We present a novel synthetic approach to produce epoxy-graphene nanocomposites by in situ polymerization, without the need of adding/removing external solvents to improve graphene dispersion. It is based on the use of 1,4-butanediol diglycidyl ether (BDE), an epoxy monomer able to efficiently produce and disperse graphene via ultrasound-induced liquid exfoliation of graphite. Suitable values of Hansen solubility parameters, surface tension and viscosity explain its ability to disperse graphene. Yields and quality of graphene produced in BDE were found comparable to those obtained when solvents such as NMP and DMF are used. Graphene-BDE dispersions were polymerized with an aliphatic diamine to produce the epoxy-based nanocomposites. The composites showed a very good level of graphene dispersion as shown by SEM images and as reflected by shifts in the glass transition temperature, decrease in reaction enthalpy and increase in Young’s modulus with respect to the neat epoxy. This strategy opens new possibilities for obtaining epoxy-based nanocomposites with graphene of high quality in a clean, straightforward way.