Flexible graphene films were prepared by the filtration of water-soluble noncovalently functionalized graphene sheets with pyrenebutyrate. The work presented here will not only open a new way for preparing water-soluble graphene dispersions but also provide a general route for fabricating conducting films based on graphene.

The gas sensors fabricated by using conducting polymers such as polyaniline (PAni), polypyrrole (PPy) and poly (3,4-ethylenedioxythiophene) (PEDOT) as the active layers have been reviewed. This review discusses the sensing mechanism and configurations of the sensors. The factors that affect the performances of the gas sensors are also addressed. The disadvantages of the sensors and a brief prospect in this research field are discussed at the end of the review.

Graphene, a one-atom layer of graphite, possesses a unique two-dimensional structure and excellent mechanical, thermal, and electrical properties. Thus, it has been regarded as an important component for making various functional composite materials. Graphene can be prepared through physical, chemical and electrochemical approaches. Among them, chemical methods were tested to be effective for producing chemically converted graphene (CCG) from various precursors (such as graphite, carbon nanotubes, and polymers) in large scale and at low costs. Therefore, CCG is more suitable for synthesizing high-performance graphene based composites. In this progress report, we review the recent advancements in the studies of the composites of CCG and small molecules, polymers, inorganic nanoparticles or other carbon nanomaterials. The methodology for preparing CCG and its composites has been summarized. The applications of CCG-based functional composite materials are also discussed.

Graphene and its functionalized derivatives are unique and versatile building blocks for self-assembly to fabricate graphene-based functional materials with hierarchical microstructures. Here we report a strategy for three-dimensional self-assembly of graphene oxide sheets and DNA to form multifunctional hydrogels. The hydrogels possess high mechanical strength, environmental stability, and dye-loading capacity, and a exhibit self-healing property. This study provides a new insight for the assembly of functionalized graphene with other building blocks, especially biomolecules, which will help rational design and preparation of hierarchical graphene-based materials.

In the past half decade, graphene oxide (GO), a precursor of graphene, 1À4 has attracted a great deal of attention due to its unique structure and outstanding physical and chemical properties. 5À8 Particularly, GO behaves like an amphiphilic macromolecule with hydrophilic edges and a more hydrophobic basal plane, 9À11 which makes it an attractive building block for the construction of various supramolecular architectures. 12,13 Furthermore, the two-dimensional (2D) structure of GO sheets provides them with various new supramolecular behaviors compared with conventional low-dimensional counterparts. Although GO sheets have been assembled into various macrostructures, such as LangmuirÀBlodgett (LB) films and paper-like films, 14À17 their 3D assembly behavior has not yet been clearly revealed. 18 We have first reported the 3D assembly of GO sheets in water solution by adding poly(vinyl alcohol) (PVA) as a crosslinker, forming a pH-sensitive supramolecular hydrogel. 19 Hydrogen bonding between GO sheets and PVA chains is believed to be responsible for the formation of the hydrogel. Recently, single-stranded DNA was also found to be a good cross-linker for preparing a GO/DNA composite hydrogel, in which πÀπ interaction was the dominant driving force. 20 Similarly, hydrogels based on chemically concerted graphene (CCG) have also been reported by us and other groups. 21À25 These examples reflect that GO and CCG are good gelators. However, the gelation of GO sheets has not yet been studied extensively and the fundamental roles behind gelation phenomena have also not been clearly revealed. Here, we report a systematical study on GO gelation. The GO-based hydrogels were prepared by acidification or adding small organic molecules, polymers, or ions as crosslinkers. The effects of different driving forces (e.g., hydrogen bonding, electrostatic interaction, and coordination) and lateral dimensions of GO sheets on GO gelation are discussed.