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The alginate/reduced graphene oxide composite hydrogels with hierarchical network structures were synthesized through the hydrothermal treatment of graphene oxide and alginate in an aqueous solution followed by ionically cross-linking of metal ions. The network of reduced graphene oxide was prepared via self-assembly of graphene nanosheets in the presence of alginate during the hydrothermal process; then, the polymer network of alginate was obtained by ionically cross-linking, forming the composite hydrogel. The effect of metal ions on the physical properties of the composite hydrogels was investigated. The prepared alginate/reduced graphene oxide composite hydrogel cross-linked by Fe3+ ions showed higher compression strength and lower swelling ratio. Moreover, due to the synergetic interaction between graphene and alginate, the composite hydrogels exhibited the improved dye adsorption performance, especially for cationic dyes. Even after ten adsorption/desorption cycles, the composite hydrogels can retain more than 90% dye adsorption capacity. The results indicated that the composite hydrogel with good stability, adsorption and regeneration ability could be a promising candidate for dye removal from waste aqueous solutions.

Three-dimensional porous sponge with good mechanical strength, high absorption capacity and recyclability is of scientific and technological interest. In this work, graphene oxide has been incorporated into poly(vinyl alcohol)–chitosan sponge during acetalization reaction of poly(vinyl alcohol) for the fabrication of macroporous and amphiphilic sponges. Mercury intrusion porosimetry and scanning electron microscopy indicate that the as-prepared sponges have interconnected open-cell structures. The incorporation of graphene oxide and the interconnected macroporous structures in the amphiphilic sponges endow them with improved absorption capacity for both water and organic liquids. Moreover, the absorbed liquids can be effectively collected through simple squeezing and the sponges can be used repeatedly while maintaining a relative high absorption capacity. The simple fabrication and improved performance of the resulting sponges suggest that they have potential industrial applications.

Poly(N-methylpyrrole) nanotubes were facilely fabricated by in situ chemical polymerization via a reactive template of MnO2 and were developed as electrode materials for the detection of dopamine. The microstructure, morphology, and chemical composition of the as-prepared poly(N-methylpyrrole) nanotubes have been investigated by X-ray powder diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Furthermore, a glassy carbon electrode (GCE) was modified with poly(N-methylpyrrole) nanotubes and showed sensitive catalytic activity for electrochemical detection of low concentration of dopamine even in the presence of and ascorbic acid.

A simple procedure is employed for the growth of silver nanoparticles (Ag NPs) onto the silicon substrate modified by poly(acrylic acid) (PAA) brushes, via: (1) surface-initiated ATRP of tert-butyl acrylate on Si surface to the preparation of poly(tert-butyl acrylate) brushes, (2) acid hydrolysis of PBA to the formation of PAA, and (3) in situ synthesis of Ag NPs via chemical reduction of AgNO3 in the presence of PAA brushes. The polymer brushes are thoroughly characterized. Moreover, Ag nanoparticles are homogeneously immobilized into the brush layer and have been used to fabricate a sensor platform of surface-enhance Raman scattering for the detection of organic molecules and effectively catalyze the reduction of methylene blue by NaBH4.

Unique polypyrrole (PPy) hydrogels are prepared by using orange IV as the dopant and FeCl3 as the oxidant. The static polymerization of pyrrole monomer in aqueous solution is accompanied with self-assembly of PPy hydrogel. PPy hydrogels not only show good electrical conductivities, but also exhibit excellent water-absorbent behaviors. The macroscopic appearance, microscopic morphology and water-absorbent behaviors of PPy hydrogels can be controlled by the choice of the reaction condition. The effects of ionic strength on the physical properties of PPy hydrogels are also studied. The results indicate that PPy hydrogels show improved water absorbencies in saline solution. Moreover, PPy hydrogel is used as an efficient adsorbent to remove Cr(VI) from aqueous solutions. PPy hydrogel exhibits much better adsorption performance than common PPy nanoparticles. This kind of PPy hydrogel is expected to be a potential candidate for water treatment.