The unique properties of graphene when coupled to plasmonic surfaces render a very interesting physical system with intriguing responses to stimuli such as photons. It promises exciting application potentials such as photodetectors as well as biosensing. With its semimetallic band structure, graphene in the vicinity of metallic nanostructures is expected to lead to non-negligible perturbation of the local distribution of electromagnetic field intensity, an interesting plasmonic resonance process that has not been studied to a sufficient extent. Efforts to enhance optoelectronic responses of graphene using plasmonic structures have been demonstrated with rather modest Raman enhancement factors of less than 100. Here, we examine a novel cooperative graphene-Au nanopyramid system with a remarkable graphene Raman enhancement factor of up to 10(7). Experimental evidence including polarization-dependent Raman spectroscopy and scanning electron microscopy points to a new origin of a drastically enhanced D-band from sharp folds of graphene near the extremities of the nanostructure that is free of broken carbon bonds. These observations indicate a new approach for obtaining detailed structural and vibrational information on graphene from an extremely localized region. The new physical origin of the D-band offers a realistic possibility of defining active devices in the form of, for example, graphene nanoribbons by engineered graphene folds (also known as wrinkles) to realize edge-disorder-free transport. Furthermore, the addition of graphene made it possible to tailor the biochemical properties of plasmonic surfaces from conventional metallic ones to biocompatible carbon surfaces.

Polyimide aerogels are mechanically strong porous solids with high surface area, low density, and dielectric constants close to 1, making them ideal materials for use as substrates for lightweight antennas. Increasing the flexibility of the polyimide aerogels extends the usefulness for conformal antennas for use on small aircraft such as unmanned air vehicles or personal air mobility vehicles. To this end, polyimide aerogels made with aromatic amines with 4–10 methylene units as flexible spacers between aromatic rings in the backbone have been fabricated. Substituting 25–75 mol % of fully aromatic 2,2′-dimethylbenzidine with these flexible diamines increases the flexibility of polyimide aerogels, making them bendable at thicknesses up to 2–3 mm. The density, dielectric constants, thermal and moisture stability, and mechanical properties of these aerogels were assessed to understand the effect of the amount and length of the methylene spacers on these properties.

This work demonstrates that neat polystyrene-blockpoly(ethylene-co-butylene)-block-poly styrene (SEBS) displays thermally responsive shape memory properties. The shape memory properties were quantitatively investigated under uniaxial tension using a dynamic mechanical analyzer and manual stretching. The shape memory properties of SEBS were found to depend on both the molecular weight of the polymer and on the shape programming conditions, including the programming temperature, applied strain, and annealing time at elevated temperature under load. The shape memory mechanism is proposed to be a result of partial stress relaxation of the block copolymer network under load and the formation of a second network with a lower glass transition temperature. This second network counterbalances the initially stretched network producing fixity and weakens first on heating, allowing recovery. Due to the unique mechanism of shape memory where the secondary network is generated from the initial network, achieving higher fixity generally occurs at the expense of high recovery and vice versa.

This review is focused on the use of ionomers in shape memory polymers. Ionomers are polymers that contain less than 15% ionic groups. The incompatibility between the ion-pairs and the polymer backbone drives microphase separation producing dispersed ionic aggregates, which can physically crosslink the polymer. Shape memory polymers are responsive materials that can be deformed to program a temporary shape and then recovered on application of an external stimulus. Through the review of the main types of ionomers used in shape memory polymers, polyurethanes and polyester ionomers, polyolefin and polyaromatic ionomers, and perfluorosulfonic acid ionomers (i.e., Nafion V R ) it will be shown that ionomers can produce robust thermoplastic shape memory polymers and in many cases impart unique properties which allow advanced shape memory materials to be obtained including antibacterial, high temperature, and multishape memory polymers.