Akira Nakasuga

Rational and practical exfoliation of graphite using well-defined poly(3-hexylthiophene) for the preparation of conductive polymer/graphene composite

Processing and manipulation of highly conductive pristine graphene in large quantities are still major challenges in the practical application of graphene for electric device. In the present study, we report the liquid-phase exfoliation of graphite in toluene using well-defined poly(3-hexylthiophene) (P3HT) to produce a P3HT/graphene composite. We synthesize and use regioregular P3HT with controlled molecular weights as conductive dispersants for graphene. Simple ultrasonication of graphite flakes with the P3HT successfully produces single-layer and few-layer graphene sheets dispersed in toluene. The produced P3HT/graphene composite can be used as conductive graphene ink, indicating that the P3HT/graphene composite has high electrical conductivity owing to the high conductivity of P3HT and graphene. The P3HT/graphene composite also works as an oxidation-resistant and conductive film for a copper substrate, which is due to the high gas-barrier property of graphene.

Evaluation of layered graphene prepared via hydroxylation of potassium-graphite intercalation compounds

Layered graphene was prepared via the hydroxylation of potassium-graphite intercalation compound (KC8) produced from exfoliated graphite flake powder. When a small amount of water was dropped onto the KC8 in an oxygen-free atmosphere, the stage structure of the intercalation compounds was broken, and agglomerated graphene was obtained. Sonication of this agglomerated graphene in buffered water containing sodium dodecyl sulfate followed by rinsing with hot water yielded gray samples. Using scanning electron microscopy, X-ray diffraction analysis, and Raman spectroscopy, the gray samples were determined to be composed of a few layers of graphene with an area of 20-100 µm2 and thickness of 1.7 nm. They were thinner than those obtained when starting with natural graphite.

Facile preparation method for polymer and exfoliated graphite composites and their application as conduction-promoting materials

This paper introduces a new carbon material with high electrical conductivity and dispersibility, as well as its application in lithium-ion batteries. This new carbon material is characterized by an edge-exfoliated structure with grafted polymer and restacking ability through removal of the grafted polymer.