Xiaoming Yang

Well-Dispersed Chitosan/Graphene Oxide Nanocomposites

Nanocomposites of chitosan and graphene oxide are prepared by simple self-assembly of both components in aqueous media. It is observed that graphene oxide is dispersed on a molecular scale in the chitosan matrix and some interactions occur between chitosan matrix and graphene oxide sheets. These are responsible for efficient load transfer between the nanofiller graphene and chitosan matrix. Compared with the pure chitosan, the tensile strength, and Youngs modulus of the graphene-based materials are significantly improved by about 122 and 64%, respectively, with incorporation of 1 wt % graphene oxide. At the same time, the elongation at the break point increases remarkably. The experimental results indicate that graphene oxide sheets prefer to disperse well within the nanocomposites.

Controlled growth of polypyrrole nanotubule/wire in the presence of a cationic surfactant

We describe herein a new facile approach to control the size and morphology of polypyrrole (PPy) nanotubular/wire structures in the presence of a cationic surfactant. The fibrillar complex of FeCl3 and methyl orange (MO), acting as a reactive self-degraded template for the formation of polypyrrole nanotubules, was modified by cetyltrimethylammonium bromide (CTAB), which plays a dual role of adjusting the size of the seed template and providing an expanded region for the growth of polypyrrole. The modified template itself reacted oxidatively with pyrrole monomers to effectively construct nanotubular/wire structures with high yield. The effect of the concentration of CTAB on the initial template and subsequent polymerization process of pyrrole was investigated systematically. In the case of introducing anionic surfactant sodium dodecyl sulfate (SDS) into the system, the MO–FeCl3 template was etched, resulting in a congregation of polypyrrole nanotubes and granules.

One-Step UV-Induced Synthesis of Polypyrrole/Ag Nanocomposites at the Water/Ionic Liquid Interface

Polpyrrole (PPy)/Ag nanocomposites were successfully synthesized at the interface of water and ionic liquid by one-step UV-induced polymerization. Highly dispersed PPy/Ag nanoparticles were obtained by controlling the experimental conditions. The results of Fourier-transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy revealed that the UV-induced interface polymerization leaded to the formation of PPy incorporating silver nanoparticles. It was also found that the electrical conductivity of PPy/Ag nanocomposite was about 100 times higher than that of pure PPy.

Synthesis and characterization of poly(3-methyl thiophene) nanospheres in magnetic ionic liquid

Poly(3-methyl thiophene) nanospheres with their size ranging around 50-60 nm have been synthesized by simply adding monomers into a magnetic ionic liquid, Bmim[FeCl(4)]. The ionic liquid leads to the formation of uniform nanospheres with a relatively narrow size distribution confined to submicrometer-sized domains. The poly(3-methyl thiophene) nanospheres were characterized by FTIR, Raman and thermogravimetric analysis (TGA). Scanning electron microscopy (SEM) was used to show the morphology of the samples. As compared with the conventional solution polymerization method, the polymerization yield and conductivity of the polymers produced in this magnetic ionic liquid system were improved.

Supramolecular [60]Fullerene Liquid Crystals Formed By Self-Organized Two-Dimensional Crystals†

Fullerene-based liquid crystalline materials have both the excellent optical and electrical properties of fullerene and the self-organization and external-field-responsive properties of liquid crystals (LCs). Herein, we demonstrate a new family of thermotropic [60]fullerene supramolecular LCs with hierarchical structures. The [60]fullerene dyads undergo self-organization driven by π-πu2005interactions to form triple-layer two-dimensional (2D) fullerene crystals sandwiched between layers of alkyl chains. The lamellar packing of 2Du2005crystals gives rise to the formation of supramolecular LCs. This design strategy should be applicable to other molecules and lead to an enlarged family of 2Du2005crystals and supramolecular liquid crystals.

Acceptor–donor–acceptor-based small molecules with varied crystallinity: processing additive-induced nanofibril in blend film for photovoltaic applications

A series of acceptor-donor-acceptor-based small molecules (SMs) with varied crystallinity were successfully synthesized. The processing additive can induce the SMs to self-organize as nanofibrils with higher crystallinity and controlled scales of nanofibrils, which have significant influence on the photovoltaic performance.

Liquid crystalline and shear-induced properties of an aqueous solution of graphene oxide sheets.

We demonstrated here the lyotropic liquid crystalline behavior of an aqueous solution of graphene oxide (GO) sheets. Scanning electron microscope experiments revealed GO sheets self-assembled into fiber-like or sheet-like structures at different concentrations under flow conditions. As a result, the solution viscosity decreased dramatically with increasing shear stress.

Production of Structural Colors with High Contrast and Wide Viewing Angles from Assemblies of Polypyrrole Black Coated Polystyrene Nanoparticles

Structural color with wide viewing angles has enormous potential applications in pigment, ink formulation, displays, and sensors. However, colors obtained from colloidal assemblies with low refractive index contrast or without black additives typically appear pale. Here, we prepare polypyrrole (PPy) black coated polystyrene (PS) nanoparticles and demonstrate well-defined colors with high color contrast and wide viewing angles under ambient light. Depending on the loading of pyrrole during polymerization, PPy nanogranules of different sizes and coverages are grafted to the surface of PS nanoparticles. The bumpy particles can self-assemble into quasi-amorphous arrays, resulting in low angle dependent structure colors under ambient light. The color can be tuned by the size of the PS nanoparticles, and the presence of the PPy black on PS nanoparticles enhances the color contrast by suppressing incoherent and multiple scattering.

One pot synthesis and characterization of novel poly(ether ester) mutiblock copolymers containing poly(tetramethylene oxide) and poly(ethylene terephthalate)

We demonstrate here a novel method to synthesize poly(ethylene terephthalate)-block-poly(tetramethylene oxide) multiblock copolymers (PET-b-PTMO-b-PET)x by the one pot melt polymerization of cyclic oligo(ethylene terephthalate)s (COETs) using poly(tetramethylene oxide) (PTMO) as a macroinitiator. Two-dimensional and one-dimensional nuclear magnetic resonance (2D and 1D-NMR) techniques, including 1H–13C Heteronuclear Single Quantum Coherence (HSQC) and 1H–1H Correlation Spectroscopy (COSY), have been used to characterize and reveal the multiblock copolymer structures and absolute molecular weights. It was found that the COETs were consumed completely within 15 minutes, and the molecular weights of the block copolymers increased linearly with reaction time. Based on the polymerization kinetic studies, a two-stage polymerization mechanism is proposed: the ring-opening polymerization of COETs by a PTMO macroinitiator to PET-b-PTMO-b-PET triblock copolymers at the first stage, followed by the in situ condensation polymerization of triblock copolymers to (PET-b-PTMO-b-PET)x multiblock copolymers at the second stage. The structures of the multiblock copolymers are further characterized and confirmed by viscometry and gel permeation chromatography (GPC). These multiblock copolymers show improved thermal stability when compared to PTMO homopolymers, and double crystalline properties from PTMO and PET segments, as revealed by thermogravimetric analysis and differential scanning calorimetry, respectively.

A fullerene dyad with a tri(octyloxy)benzene moiety induced efficient nanoscale active layer for the poly(3-hexylthiophene)-based bulk heterojunction solar cell applications

A bulk tri(octyloxy)benzene moiety grafted onto fullerene (PCBB-C8) was successfully synthesized, which could effectively induce poly(3-hexylthiophene) (P3HT) to form highly ordered bulk heterojunction structure without any external treatment. This ordered active layer exhibits good photovoltaic performance.