Electrically conductive polymer/rGO (reduced graphene oxide) films based on styrene and n-butyl acrylate are prepared by a variety of aqueous latex based routes involving ambient temperature film formation. Techniques based on miniemulsion polymerization using GO as surfactant and "physical mixing" approaches (i.e., mixing an aqueous polymer latex with an aqueous GO dispersion) are employed, followed by heat treatment of the films to convert GO to rGO. The distribution of GO sheets and the electrical conductivity depend strongly on the preparation method, with electrical conductivities in the range 9 × 10 −4 to 3.4 × 10 2 S/m. Higher electrical conductivities are obtained using physical mixing compared to miniemulsion polymerization, which is attributed to the former providing a higher level of self-alignment of rGO into larger linear domains. The present results illustrate how the distribution of GO sheets within these hybrid materials can to some extent be controlled by judicious choice of preparation method, thereby providing an attractive means of nanoengineering for specific potential applications.

We have reported cellulose particles with a spongy structure that we prepared by the solvent releasing method (SRM) from cellulose droplets composed of cellulose, 1-butyl-3-methylimidazoliumchrolide ([Bmim]Cl), and N,N-dimethylformamide (DMF). The spongy structure collapsed as the medium evaporated, resulting in dense cellulose particles. In this study, we encapsulated the hydrophilic and hydrophobic fluorescent substances in these particles to investigate the use of such particles in potential applications that require encapsulating of substances (e.g., drug delivery). Wet cellulose particles retained their spongy structure in both hydrophobic and hydrophilic media. When the spongy cellulose particles were dispersed in a solution containing nonvolatile solutes, these solutes were driven into the cellulose particles as media evaporated. Subsequently, the cellulose particles collapsed and encapsulated the nonvolatile solutes. Regardless of whether the solute was hydrophilic or hydrophobic, the encapsulation efficiency exceeds 80%. The maximum loading reflected the saturated solubility of solute in solution that filled the cellulose beads. Moreover, the encapsulated solute was released by dispersing the cellulose beads in the solvent, and the rate of release of the encapsulated solute could be controlled by coating the cellulose beads with a conventional polymer.

We reported the preparation of porous cellulose particles by the solvent-releasing method, in which a solution of cellulose, dissolved in 1-butyl-3-methylimidazolium chloride and N,N′-dimethylformamide, was dropped into a large amount of 1-butanol using a syringe. The obtained particles had a high specific area because of their porous structure. Herein, to functionalize the cellulose particles, carboxylate groups are introduced into their porous structure by 2,2,6,6-tetramethylpiperidine-1-oxyl-mediated oxidation and ion exchange of carboxylate groups to Ag cations is conducted. Composite cellulose/Ag particles were synthesized by the reduction reaction using the carboxylate groups as a scaffold without free silver nanoparticles in the medium. The obtained composite particles exhibited a high catalytic ability, which was evaluated by examining the reduction of 4-nitrophenol. Moreover, we determined that the catalytic efficiency was maintained for at least three cycles by immobilizing Ag on cellulose particles.

Near-infrared (NIR) light irradiation induced the transformation of polypyrrole (PPy) to nitrogen-containing carbon (NCC) material due to its light-toheat photothermal property. The temperature of the PPy increased over 700 °C within a few seconds by the NIR laser irradiation, and elemental microanalysis confirmed the decreases of hydrogen and chloride contents and increases of carbon and nitrogen contents. Monodispersed polystyrene (PS)-core/PPy shell particles (PS/PPy particles) synthesized by aqueous chemical oxidative seeded polymerization were utilized as a precursor toward monodispersed NCC capsules. When the NIR laser was irradiated to the PS/PPy particles, the temperature rose to approximately 300 °C and smoke was generated, indicating that the PS component forming the core was thermally decomposed and vaporized. Scanning electron microscopy studies revealed the successful formation of spherical and highly monodispersed capsules, and Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy studies confirmed the capsules consisted of NCC materials. Furthermore, sunlight was also demonstrated to work as a light source to fabricate NCC capsules. The size and thickness of the capsules can be controlled between 1 and 80 μm and 146 and 231 nm, respectively, by tuning the size of the original PS/PPy particles and PPy shell thickness.

In this work, a novel sponge cellulose fluorescence spherical (CS–CDs) was prepared by an in situ microwave method using cellulose as a base material, polyethylenimine (PEI) as a nitrogen-doping reagent, and citric acid (CA) as an external carbon source. The CS–CDs were used for highly sensitive selective detection of Hg2+ and semiquantitative visual detection of Cu2+ in aquatic environments. Their excellent fluorescence properties and porous structure enable the CS–CDs to adsorb and detect these ions quickly and sensitively, and they can detect Hg2+ selectively with a detection limit of 26 nM. Additionally, an interesting phenomenon was observed where the color of the cellulose sphere changes continuously from inherent pale yellow to deep green as the Cu2+ adsorption increases from 3 to 60 μM, indicating that the CS–CDs can be used for semiquantitative visual detection of Cu2+. The fluorescence and visual detection limits for Cu2+ are 0.11 and 3 μM, respectively; these are both considerably lower than the allowable content of Cu2+ (20 μM) in potable water. The discoloration mechanism of Cu2+ adsorption by CS–CDs was studied. It can be considered that after CS–CDs adsorb Cu2+, a large amount of Cu2+ amine complexes form, aggregate, and concentrate on the cellulose sphere substrate to develop the color. Finally, we used the CS–CDs to analyze tap and river water based on highly reproducible results. This cellulose sponge-based device could be used to protect probes from environmental interference and is sufficiently stable to withstand at least 22 cycles of exposure to ethylenediaminetetraacetic acid.