Laura J. Romasanta

Graphene filled polymer nanocomposites

Graphene has attracted the attention of a growing number of scientists from several disciplines due to its remarkable physical properties and chemical functionalisation capabilities. This review presents an overview of graphene/polymer nanocomposites discussing preparation, properties and potential applications. The challenges and outlook of these emerging polymer nanocomposites are also discussed.

Functionalised graphene sheets as effective high dielectric constant fillers

A new functionalised graphene sheet (FGS) filled poly(dimethyl)siloxane insulator nanocomposite has been developed with high dielectric constant, making it well suited for applications in flexible electronics. The dielectric permittivity increased tenfold at 10 Hz and 2 wt.% FGS, while preserving low dielectric losses and good mechanical properties. The presence of functional groups on the graphene sheet surface improved the compatibility nanofiller/polymer at the interface, reducing the polarisation process. This study demonstrates that functionalised graphene sheets are ideal nanofillers for the development of new polymer composites with high dielectric constant values.PACS: 78.20.Ci, 72.80.Tm, 62.23.Kn

Towards materials with enhanced electro-mechanical response: CaCu3Ti4O12-polydimethylsiloxane composites

We describe a straightforward production pathway of polymer matrix composites with increased dielectric constant for dielectric elastomer actuators (DEAs). Up to date, the approach of using composites made of high dielectric constant ceramics and insulating polymers has not evidenced any improvement in the performance of DEA devices, mainly as a consequence of the ferroelectric nature of the employed ceramics. We propose here an unexplored alternative to these traditional fillers, introducing calcium copper titanate (CCTO) CaCu3Ti4O12, which has a giant dielectric constant making it very suitable for capacitive applications. All CCTO–polydimethylsiloxane (PDMS) composites developed display an improved electro-mechanical performance. The largest actuation improvement was achieved for the composite with 5.1 vol% of CCTO, having an increment in the actuation strain of about 100% together with a reduction of 25% in the electric field compared to the raw PDMS matrix.

Reactive Nanocomposite Foams

One of the most interesting and most accessible opportunities of nanofillers is the reinforcement of fine structures in which conventional fillers cannot be readily accommodated, such as polymer foams. This paper reviews the progress to date towards the development of reactive foam nanocomposites, in particular polyurethane and silicone foams. The discussed systems are summarized based on the types of nanofillers used, i.e. nanoparticles, rod-like, and plate-like systems. The effect of nanofillers on the foaming process, cellular structure and properties is critically reported along with a summary of the measured improvements in the mechanical, electrical and thermal properties of the resulting nanocomposites.