With advances in nanoscience and nanotechnology, there is increasing interest in polymer nanocomposites, both in scientific research and for engineering applications. Because of the small size of nanoparticles, the polymer–filler interface property becomes a dominant factor in determining the macroscopic material properties of the nanocomposites. The glass‐transition behaviors of several epoxy nanocomposites have been investigated with modulated differential scanning calorimetry. The effect of the filler size, filler loading, and dispersion conditions of the nanofillers on the glass‐transition temperature (Tg) have been studied. In comparison with their counterparts with micrometer‐sized fillers, the nanocomposites show a Tg depression. For the determination of the reason for the Tg depression, the thermomechanical and dielectric relaxation processes of the silica nanocomposites have been investigated with dynamic mechanical analysis and dielectric analysis. The Tg depression is related to the enhanced polymer dynamics due to the extra free volume at the resin–filler interface. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3849–3858, 2004

One-dimensional In(2)O(3)-TiO(2) heteroarchitectures with high visible-light photocatalytic activity have been successfully obtained by a simple combination of electrospinning technique and solvothermal process. The as-obtained products were characterized by field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-vis spectra. The results revealed that the secondary In(2)O(3) nanostructures were successfully grown on the primary TiO(2) nanofibers substrates. Compared with the pure TiO(2) nanofibers, the obtained In(2)O(3)-TiO(2) heteroarchitectures showed enhancement of the visible-light photocatalytic activity to degrade rhodamine B (RB) because of the formation of heteroarchitectures, which might improve the separation of photogenerated electrons and holes derived from the coupling effect of TiO(2) and In(2)O(3) heteroarchitectures. Moreover, the In(2)O(3)-TiO(2) heteroarchitectures could be easily recycled without the decrease in the photocatalytic activity because of their one-dimensional nanostructural property.

Well-designed hierarchical nanostructures with one dimensional (1D) TiO(2) nanofibers (120-350 nm in diameter and several micrometers in length) and ultrathin hexagonal SnS(2) nanosheets (40-70 nm in lateral size and 4-8 nm in thickness) were successfully synthesized by combining the electrospinning technique (for TiO(2) nanofibers) and a hydrothermal growth method (for SnS(2) nanosheets). The single-crystalline SnS(2) nanosheets with a 2D layered structure were uniformly grown onto the electrospun TiO(2) nanofibers consisted of either anatase (A) phase or anatase-rutile (AR) mixed phase TiO(2) nanoparticles. The definite heterojunction interface between SnS(2) nanosheets and TiO(2) (A or R) nanoparticles were investigated by high resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). Moreover, the as-prepared SnS(2)/TiO(2) hierarchical nanostructures as nanoheterojunction photocatalysts exhibited excellent UV and visible light photocatalytic activities for the degradation of organic dyes (rhodamine B and methyl orange) and phenols (4-nitrophenol), remarkably superior to the TiO(2) nanofibers and the SnS(2) nanosheets, mainly owing to the photoinduced interfacial charge transfer based on the photosynergistic effect of the SnS(2)/TiO(2) heterojunction. Significantly, the SnS(2)/TiO(2) (AR) hierarchical nanostructures as the tricomponent heterojunction system possessed stronger photocatalytic activity than the bicomponent heterojunction system of SnS(2)/TiO(2) (A) hierarchical nanostructures or TiO(2) (AR) nanofibers, which was discussed in terms of the three-way photosynergistic effect between SnS(2), TiO(2) (A) and TiO(2) (R) component in the SnS(2)/TiO(2) (AR) heterojunction resulting in the high separation efficiency of photoinduced electron-hole pairs, as evidenced by photoluminescence (PL) and surface photovoltage spectra (SPS).

Tubular nanocomposites of silver nanoparticles (AgNPs)/silica nanotubes (SNTs) with the nearly uniform diameters of 250-350 nm were successfully fabricated by combining the single capillary electrospinning technique (for SNTs as the supports) and an in situ reduction approach (for AgNPs). The highly dispersed AgNPs assembled on the inner and outer surface of SNTs through the in situ reduction of Ag + by Sn 2+ ions were confirmed by transmission electron microscopy (TEM), UV-Vis absorption spectra and X-ray photoelectron spectroscopy (XPS). It was interesting to note that the size of AgNPs on the surface of SNTs could be controlled by appropriately adjusting the amount of ammonia solution during the above in situ reduction reaction. The catalytic activities of the as-prepared tubular nanocomposites were evaluated by using a model reaction based on the reduction process of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP) in the presence of NaBH 4 as the reductant. The results indicated that all the tubular nanocomposites catalysts with high specific surface area (185-250 m 2 g À1 ) exhibited excellent catalytic activities because the highly dispersed AgNPs were exposed on the inner and outer surface of electrospun SNTs, allowing effective contact with the reactants and catalysis of the reaction. In particular, the tubular nanocomposite catalysts containing small size AgNPs had higher catalytic activities than those containing the large size ones, which was attributed to the size-dependent Ag redox potential and surface-to-volume ratio influencing interfacial electron transfer from AgNPs surface to 4-NP in the presence of highly electron injecting BH 4 À ions. Those tubular catalysts based on AgNPs/SNTs nanocomposites could be easily recycled without a decrease of the catalytic activities due to their one-dimensional nanostructural property.

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