Hou Bin Li

Synthesis and Characterization of Polyaniline Dopd with Anionic Spherical Polyelectrolyte Brushes

The synthesis of polyaniline (PANI) doped with anionic spherical polyelectrolyte brushes (ASPB) (PANI/ASPB nanocomposite) by means of in situ chemical oxidative polymerization were presented. The PANI/ASPB nanocomposite was characterized by Fourier trans-form infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Energy dispersive x-ray detector (EDX), and Thermo-gravimetric analysis (TGA). Results showed that PANI/ASPB nanocomposite was successfully fabricated with regular morphology. Investigation of the electrical conductivity at room temperature showed that the electrical conductivity of PANI/ASPB nanocomposite was 9.03 S/cm, which was higher than that of PANI (2.7 S/cm). The measurement of dispersity demonstrated that PANI/ASPB nanocomposite had enhanced dispersity in water.

Synthesis of VO2(A) Nanostructures by a Hydrothermal Method and their Transition to VO2(M)

VO2(A) nanobelts have been synthesized using V2O5, H2O2, ethanol, H2O as the starting materials through a facile hydrothermal method. The as-obtained products were characterized by X-ray powder diffraction (XRD), X-ray photoelecton spectroscopy (XPS), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). Some parameters, such as, the reaction time, reaction temperature and the ratio of EtOH/H2O, have greatly influenced on the phases and morphologies of the final products. It was found that VO2(A) can be converted to VO2(M) at 700 °C for 2 h for the first time. Furthermore, the phase transition properties of VO2(A) and VO2(M) phases were respectively studied.

Synthesis and Characterization of Star-Shaped Polylactic Acid with Polyhedral Oligomeric Silsesquioxanes

A series of star-shaped polylactic acid was synthesized using L-lactic acid (L-LA) and octa(γ-chloroammoniumpropyl) octasilsesquioxane (POSS-NH3Cl) by in the presence of stannous(II) octanoate (Sn(Otc)2) catalyst. The structures and properties of these dendritic polymers were characterized by FTIR, 1H-NMR and TGA, respectively. These results demonstrated that the chemical reaction between POSS-NH3Cl and L-LA had been taken place, and the novel star-shaped polylactic acid (POSS-g-PLLA) had been synthesized. And thermal properties, such as melting temperature and decomposition temperature, were obviously improved along with the increment of the added amount of POSS-NH3Cl. The decomposition temperature of POSS-g-PLLA was higher ca. 70°C higher than that of PLLA, also higher 65°C than that of POSS-NH3Cl/PLLA.

The Research of Poly Propylene Carbonate /Nano-SiO2 Composites

Biodegradable poly (propylene carbonate) (PPC) composite with a slight improvement in the thermal stability and tensile strength was successfully prepared by incorporating a low content of nano-SiO2. Tensile tests demonstrate the better mechanical properties of the composites prepared in this study. The obtained composites increases sharply from 1.57Mpa to 12.04Mpa by incorporating 5wt% nano-SiO2. Furthermore, the composites show approximately 8°C higher glass transition temperature (Tg) than that of neat PPC.The Tdmax of composite with 5wt% of nano-SiO2 was about 40°C higher than that of neat PPC.

Synthesis of Silica Microspheres Filler for PDMS

A new kind of silica microspheres were first synthesized with chloropropyltrimethoxysilane (WD30) and tetraethoxysilane (TEOS) by sol-gel method. And hybrid membrane was prepared by incorporating the as prepared filler into polydimethylsiloxane (PDMS). The IR, swelling density(Dsw) and mechanical properties of these composites membranes were studied by means of IR analysis and tensile testing. The experimental results showed that both mechanical properties of these composites were significantly improved by using the as-synthesized filler. The filler synthesized in this research not only increased the volume and reduce the cost of HPDMS, but also reacted with the PDMS. The vulcanztion density was increasedwith the interaction between the filler and the PDMS chains. This new kind of silica microspheres is an effective reinforcement filler for PDMS composite.

Preparation of Silver Nanoplates and Application in PCB Ink-Jet

Compared with traditional etch processing, inkjet technology has the features of simpler workmanship, less resources-utilizing, lower cost and environmentally friendly adaptation, which is sure to be another innovation of printed circuit board(PCB) technology. In this paper, size and shape controlled silver nanoparticles have been synthesized，which was used as conductive medium in ink-jet inks. Then it was printed into conductive lines on epoxy resin by a drop-on-demand inkjet printer. PVP was used as a polymeric stabilizer providing both electrostatic and steric stabilization. Ag2C2O4 was used to prepared spherical nano-silver. In the preparation of flake-like silver powders, the fully inorganic phase system contains AgNO3 as a silver precursor, DMF as a as a media dissolving silver salt, and PVP as a reducing reagent. The morphologies and structures of the nanoparticles were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). It was shown that the sample is silver with cubic asymmetry from the pattern of XRD. TEM images indicated that the size of spherical nano-particles was no more than 20 nm. But the small triangular nanoplates, with rather narrow size distribution, were in the range from 20nm up to 60 nm in edge length. The electrical conductivity was also measured by the four-probe tested method after calcined on the substrates. It was shown that the conductivity was 25S/cm when adding the spherical powders and the nano-silver ink has been successfully designed for inkjet printing.

Graft Polymerization of Acrylic Acid onto Polypropylene Film: Immobilization of Chitosan Nanoparticles onto Grafted Films

In this paper the aim is to immobilize chitosan nanoparticles on the surface of the polypropylene film, aqueous phase thermal decomposition characteristics of ammonium persulfate is used. The PP film is first hydroxylation pretreated in the protection of the high-purity nitrogen. And then ceric ammonium nitrate acting as an initiator, induce graft polymerization of acrylic acid on the hydroxylated treated PP film. Thus, carboxyl functional groups are grafted on the surface of PP film. Finally chitason namoparticles are fixed on PP film by the reaction of carboxyl group and the amino group of chitosan. Experimental results show that: when the reaction temperature is 60 ° C, the concentration of acrylic acid is 8% (w/w), the reaction time reaches 4h, the concentration of ceric ammonium nitrate is 2mM, the optimum grafting ratio is obtained, which is up to 0.6008×10-7mol/cm2. Total reflection Fourier transform infrared spectroscopy absorption peaks appear at 1712cm-1, indicating that the-COOH has been successfully grafted to the film surface; the SEM scanning the film surface shows that the chitosan nanoparticles were perfectly immobilized on the modified film. Key words: Acrylic acid, Polypropylene film, Chitosan nanoparticles, Graft polymerization

The Potential Applications of W- and Mo-Doped VO2 Nanobelts to the Functional Packaging Materials

The first–order metal–sinsulator phase transition in VO2 is characterized by an ultrafast several orders of magnitude change in optical transmittance and electrical conductivity, which makes VO2 an attractive candidate for the potential application in thermochromic coatings and functional packaging materials. Herein, W– and Mo–doped VO2 nanobelts were successfully synthesized by a facile hydrothermal method. The as–obtained products were characterized by X–ray powder diffraction (XRD), X–ray photoelecton spectroscopy (XPS), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT–IR). The results revealed that W or Mo atoms were successfully doped into the crystal lattice of VO2 matrix. It was found that the phase transition temperature of doped VO2 could be simply tuned by changing the doping concentration of W or Mo atoms. Furthermore, the variable–temperature infrared spectra disclosed that the doped VO2(M) had novel optical switching properties, indicating that the as–obtained products can be used as the intelligent packaging materials.

Research on a Neotype of Silica Sphere Filler

A neotype of silica microspheres were synthesized with chloropropyltrimethoxysilane (WD30) and tetraethoxysilane (TEOS) by sol-gel method. And the thermal properties of the filler both in nitrogen and in air condition were studied by means of thermogravimetric analysis. The morphology of the filler was measured by TEM. The so synthesized spheres were added into the silicone rubber whose mechanical strength was increased greatly. The molecular structure of the filler and the silicone rubber were characterized by FTIR. The possible strengthen mechanism of the filler was discussed. The neotype silica sphere researched in this paper could react with the PDMS chains which perfects the vulcanization of the silicone rubber. This kind of silica sphere exhibits many merits for usage as filler.

Preparation and Electrochemical Properties of VO2(B) Nanobelts

VO2(B) nanobelts have been successfully prepared in V2O5 and water mixed suspension assisted by polyvinyl alcohol (PVA) via a mild hydrothermal approach. The as-obtained VO2 nanobelts are several hundred nanometers to several micrometers long, typically 100-300 nm wide and about 20-30 nm thick. It was found that PVA could not only act as the reducing reagent but also as the structure-directing reagent. Besides, the PVA-assisted solid-solution-solid (SSS) transformation mechanism was proposed to illuminate the possible formation mechanism of VO2(B) nanobelts. Furthermore, the electrochemical properties of VO2(B) nanobelts were studied and they exhibited a high initial discharge capacity of 268 mAh/g, indicating that VO2(B) nanoblets are promising electrode materials in lithium battery.