Graphene-polymer composites for pulse lasers

Polymer nanocomposites combine two concepts in material design; that is, composites and nanometer-size materials. Tailor-made nanocomposites that exploit the superlative properties of both components can show enhanced performance in wide-ranging applications from flexible packaging, printable electronics, and interlayer dielectrics to thermoplastics. Polymer nanocomposites that are reinforced with nanofillers such as one-dimensional nanowires (Chang et al. 2006; Vivekchand et al. 2006) or two-dimensional layered materials (Emmanuel 1996; Ray and Okamoto 2003; Sheng et al. 2004) exhibit enhanced mechanical, electrical, and thermal properties. Carbon-based nanofillers that include graphite nanoplatelets (Ramanathan et al. 2007; Wakabayashi et al. 2008; Zheng and Wong 2003), carbon nanotubes (Ajayan et al. 2000; An et al. 2004; Coleman et al. 2006; Grunlan et al. 2004; Munoz et al. 2005; Ramanathan et al. 2005), graphite oxide (Cassagneau et al. 2000; Kotov et al. 1996; Kovtyukhova et al. 1999), and functionalized graphene (Ramanathan et al. 2008; Stankovich et al. 2006; Verdejo et al. 2008; Vickery et al. 2009) have attracted considerable attention due to their intrinsic mechanical strength. In particular, graphene, a single layer of aromatic carbon, has one of the strongest in-plane bonds among all materials as well as superior thermal and electrical conductivity. The conjugated graphene sheet can be readily functionalized through noncovalent p-p stacking or covalent C-C coupling reactions. By derivatizing graphene with different organic moieties, the solubility of graphene can be tuned to suit different solvents needed for the processing of composite films. Certain functional groups can broaden the properties of the graphene through the formation of donor-acceptor complex with graphene, which affords tunability in electrical conductivity and optical and photovoltaic properties (dPotts et al. 2010). It can be expected that based on the superlative properties of graphene and its derivatives, significant improvement in viscosity, electrical, mechanical, and thermal properties of the graphene-polymer composite can be achieved. For example, it has recently been demonstrated that the properties of functionalized graphene-polymer (i.e., polystyrene and poly(methyl methacrylate) [PMMA]) rival that of single-walled carbon nanotube (SWNT) -polymer composites (Ramanathan et al. 2008; Stankovich et al. 2006). Graphene should provide good integration with the polymer matrix due to its sheetlike properties, which provide maximum surface area for p - p stacking with polymer host. The carboxylic and hydroxyl functional groups on the edges of graphene oxide (GO) can also act as linkers for joining organic segments together and impart mechanical strength.