PVA Nanocomposite Films Research Articles

Electrochemically modified graphite nanosheets and their nanocomposite films with poly(vinyl alcohol)

AbstractA novel, facile, and environment friendly approach based on electrochemical oxidation and ultrasonication was presented to prepare electrically conductive graphite nanosheets (GNs). The as‐prepared GNs with a large aspect ratio were then incorporated into poly (vinyl alcohol) (PVA) by solution compounding. The GNs can be well and stably dispersed in water medium without the need for polymeric or surfactant stabilizers because of the electrochemical modification and their PVA nanocomposite films exhibit enhanced electrical, thermal, and mechanical properties compared with pure PVA film. Electrical resistivity decreases by 4 orders of magnitude with a percolation threshold of ca. 6 wt%. A significant improvement in thermal stability of 45°C and a large shift in glass transition temperature of 14°C are obtained, together with improved mechanical strength and toughness with the optimal GNs loading. POLYM. COMPOS., 31:1770–1775, 2010. © 2010 Society of Plastics Engineers.

Poly (vinyl alcohol) thin film filled with CdSe–ZnS quantum dots: Fabrication, characterization and optical properties

A transparent poly (vinyl alcohol) (PVA) nanocomposite thin film (30–50 nm) reinforced with core/shell cadmium selenide (CdSe)/zinc sulfide (ZnS) quantum dots (QDs) was fabricated by a drop-casting method. A narrow peak at ∼556 nm observed in the UV–vis spectrum indicates the uniformly dispersed QDs in the PVA matrix. FT-IR analysis indicates the interaction between the QDs and the polymer matrix. Both PVA and PVA-QDs nanocomposite thin films show polarized light dependent absorption properties with several different absorption peaks. As compared to the only fluorescent emission peak at 574 nm of QDs, the pure PVA and PVA-DDs nanocomposites show an excitation wavelength dependent fluorescent emission property.

Poly(vinyl alcohol)-assisted dispersion of multiwalled carbon nanotubes in aqueous solution for electroanalysis

Multiwalled carbon nanotubes (MWNTs) were directly dispersed into poly(vinyl alcohol) (PVA) aqueous solution without functionalization of their surface. A MWNTs–PVA nanocomposite film is prepared by cast deposition from a homogeneous MWNTs–PVA solution. The morphology of the resulting MWNTs–PVA nanocomposite film is characterized by atomic force microscopy (AFM). Well-defined voltammetric responses are observed for the Fe ( CN ) 6 4 - / Fe ( CN ) 6 3 - redox system in aqueous 0.1 M KCl at MWNTs–PVA nanocomposite film modified glassy carbon electrode. In contrast to electrode coated only with PVA, both anodic and cathodic peak currents depended linearly on the square root of the scan rate over the range of 25–200 mV/s at MWNTs–PVA nanocomposite film modified electrode, which suggests diffusion-control and fast electron conduction within the film.

Novel Silver/Poly(vinyl alcohol) Nanocomposites for Surface‐Enhanced Raman Scattering‐Active Substrates

AbstractSummary: Surface‐enhanced Raman scattering (SERS)‐active substrates with high enhancement were prepared by an in situ reduction method. Novel silver/poly(vinyl alcohol) (PVA) nanocomposite films were obtained, in which the silver nitrate, poly(γ‐glutamic acid) (PGA), and PVA acted as precursor, stabilizer, and polyol reducant, respectively. The UV‐visible spectra of the as‐fabricated films showed that the surface plasmon resonance (SPR) absorption band was narrow and of a stronger intensity, which indicates that the Ag nanoparticle size distribution on the substrate was highly uniform. This finding was further confirmed by X‐ray diffraction (XRD), transmission electron microscopy (TEM), and field‐emission scanning electron microscope (FE‐SEM) measurements. It was found that a PGA‐stabilized PVA nanocomposite film revealed the presence of well‐dispersed spherical silver nanoparticles with an average diameter of 90 nm. The new substrate presents high SERS enhancement and the enhanced factor is estimated to be 106 for the detection of benzoic acid.The Raman scattering enhancement factor for the Raman spectra of benzoic acid on the various nanocomposite films.imageThe Raman scattering enhancement factor for the Raman spectra of benzoic acid on the various nanocomposite films.