Search

A systematic study on the influence of the dielectric/organic interface properties on the electrical characteristics of field-effect transistors based on polyphenylenevinylene derivatives is reported. The hole mobility values obtained with hexamethyldisilazane and polymer dielectrics are found to be highest for (poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]) PPV-based field-effect transistors.

A meta-linked anionic conjugated polyelectrolyte m-PPYPE-SO3Na was synthesized and characterized by UV-vis, FT-IR, and photoluminescence spectroscopy. It is brown solid readily soluble in water and methanol. The UV-vis absorption spectra of the polymer show strong absorption bands, which correspond to the π-π" transition of π-conjugated segments. Fluorescence spectra in different solvents show that this kind of polymer has solvent-dependency. It was found that the existence of polymer-type surfactant significantly increased the intensity of fluorescence of the polymer. The fluorescence of the polymer in water solution could be effectively quenched by methyl viologen. Linear fit of the quenching plots affords Stern-Volmer constants (Ksv) of 5.65×105M-1 for intrinsic fluorescence emission of the polymer m-PPYPE-SO3Na and this revealed its good fluorescence sensitivity. [ABSTRACT FROM AUTHOR]

Two new hyperbranched fluorescent conjugated polymers containing pyridine units were synthesized via Heck coupling reaction and Sonogashira coupling reaction, respectively, and characterized by H NMR, C NMR, FTIR, and GPC. The copolymers are readily soluble in common organic solvents such as chloroform, THF, and DMF. Thermal analysis revealed that the copolymers had good thermal stability. The fluorescence quenching behaviors of the hyperbranched copolymers by metal ions were studied. It was found that the fluorescence of the copolymers can be effectively quenched by Pd. Moreover, the two hyperbranched copolymers exhibited different quenching efficiency, which may be related to difference in the hindrance for the chelation of pyridine unit with metal ions of the two polymers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 [ABSTRACT FROM AUTHOR]

In this study, glycidyl methacrylate was copolymerized with poly(ethylene glycol) methyl ether methacrylate to obtain a copolymer {poly[glycidyl methacrylate-poly(ethylene glycol) methyl ether methacrylate] [P(GMA-PEGMA)]}, which was crosslinked with α,ω-diamino poly(propylene oxide) (Jeffamine) at various weight ratios and molecular weights to form novel gel polymer electrolytes (GPEs). The crosslinked copolymers were characterized by Fourier transform infrared spectroscopy and thermal analysis. The crosslinked polymers were amorphous in the pristine state and became crystallized after they were doped with lithium electrolyte. Furthermore, the crosslinking degree of the crosslinked polymers increased with increasing weight ratio of Jeffamine, and both the swelling properties and mechanical behaviors of the crosslinked polymers were heavily affected by the weight ratio and molecular weight of Jeffamine. The ionic conductivity (σ) of the GPEs from the crosslinked copolymers was determined by alternating-current impedance spectroscopy. A higher molecular weight and increased weight ratio of Jeffamine resulted in a higher σ. The GPE based on P(GMA-PEGMA) crosslinked with an equal weight of Jeffamine D2000 exhibited the highest σ of 8.29 × 10 S/cm at 25°C and had a moderate mechanical strength. These crosslinked copolymers could be potential candidates for the construction of rechargeable lithium batteries. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 [ABSTRACT FROM AUTHOR]

Hyperbranched polycarboxylates (HBPC) with different alkali metal cations (Li, Na, and K) were prepared and characterized by H-NMR and thermal gravimetric analysis. Thin film humidity sensors based on HBPC and its composite with ZnO nanorods were fabricated. The morphologies of films of HBPC and the nanocomposite were investigated by atomic force microscopy, which revealed uniform distribution of ZnO nanorods in HBPC. The humidity-sensitive characteristics of HBPC and the nanocomposite were investigated at room temperature. It was found that the type of cations significantly affected the humidity-sensing behaviors of HBPC. In addition, the nanocomposite exhibited better humidity-sensitive properties than HBPC alone. Its impedance decreased for about three orders of magnitude over the range 19-97% RH, showing high sensitivity. Moreover, the nanocomposite exhibited fast response (∼ 9 and 10 s for response and recovery time between 97% RH and 33% RH, respectively) and small hysteresis (∼ 1.4% RH). The improved humidity-sensing behaviors of the nanocomposite over HPBC alone is explained by taking into account the hyperbranched structure of the polymer and the special interactions of the polymer and ZnO with water molecules. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 [ABSTRACT FROM AUTHOR]

Amphiphilic conetwork–structured copolymers containing different lengths of ethylene oxide EO chains as ionophilic units and methyl methacrylate MMA chains as ionophobic units were prepared by free radical copolymerization and characterized by FTIR and thermal analysis. Polymer gel electrolytes based on the copolymers complexed with liquid lithium electrolytes dimethyl carbonate DMC : diethyl carbonate DEC : ethylene carbonate EC 1 : 1 : 1 WWW, LiPF61.0M were characterized by differential scanning calorimetry and impedance spectroscopy. A maximum ion conductivity of 4.27 × 10−4Scm at 25oC was found for the polymer electrolyte based on PEG2000bGMAcoMMA with long EO groups. Moreover, the effect of temperature on conductivity of the amphiphilic polymer electrolytes obeys the Arrhenius equation. The good room temperature conductivity of the polymer electrolytes is proposed to relate to the enhancement in the amorphous domain of the copolymers due to their amphiphilic conetwork structure. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [ABSTRACT FROM AUTHOR]

The article investigates the synthesis of silicon-containing polymer and the interaction of d-orbital of the silicon atoms with thiophene rings. The synthetic routes of this silicon-containing polymer and its mononers are shown. The authors studied the electrochemical properties of the polymer solution by cyclic voltammetry. They conclude that synthesis of a silicon-containing conjugated polymer based on poly(heteroarylene methine) may result from its quinoid structure.

Studies organic light emitting diodes based on multi-wall carbon nanotubes modified electrode. Current-voltage characteristics of the light-emitting diodes; Light-emitting area.

Discusses the third-order optical nonlinearity of novel π-conjugated soluble palladium-polyyne polymers. Synthesis of the new palladium-polyyne polymers by condensation reactions; Stability in air of the polymers; Measurement of the weight average molecular weight and molecular weight distribution of the polymers on gel permeation chromatography.

Multi-walled carbon nanotubes (MWNTs) grafted with sodium polystyrenesulfonate (NaPSS) were deposited on an interdigitated gold electrode decorated with a layer of positively charged poly(diallyldimethylammonium chloride) by a self-assembly method. Then polyaniline (PANI) was in situ polymerized on the surface of the MWNTs to prepare a composite. The structure and morphology of the composite were investigated by Raman spectroscopy and scanning electron microscopy. The electrical responses of the composite to triethylamine vapor of low concentrations were measured at room temperature. It was found that the composite exhibited a linear response to the vapor in the range of 0.5-8 ppm with the highest sensitivity of [?]80%, which is much higher than that of MWNTs and PANI separately, and an obvious synergetic effect was observed. In addition, the detection limit was as low as the ppb level, and reversible and relatively fast responses (t90%[?]200 s and [?]10 min for sensing and recovery, respectively) were observed. The sensing characteristics are highly related to the gas responses of PANI, and a sensing mechanism considering the interaction of MWNTs and PANI was proposed. [ABSTRACT FROM AUTHOR]

Multi-walled carbon nanotubes (MWNTs) were dispersed in the matrix of quaternized and crosslinked poly(4-vinylpyridine) (QC-P4VP) to prepare a composite via solution blending and heat treatment. The composite was characterized by FT-IR spectroscopy and scanning electron microscopy. Thin film humidity sensors based on the composite were fabricated and their electrical responses to relative humidity (RH) were investigated at room temperature. The composite sensor showed much higher response magnitude than the sensor based on MWNTs (impedance increase of ~4700% from 7 to 90%RH). Meanwhile, its impedance at low humidity was significantly decreased with respect to that of QC-P4VP based sensor. Furthermore, it could detect very low humidity with good sensitivity (impedance change of 16%/%RH over 1-30%RH), and demonstrate its capability of realizing full-range measurement of humidity. The effect of content of MWNTs, poly(4-vinylpyridine) (P4VP) and the additive, molecular weight of P4VP, temperature and testing frequency on the humidity sensing properties of the composite sensors has been examined. A sensing mechanism was proposed by considering the MWNT conductive network in the polyelectrolyte matrix. [ABSTRACT FROM AUTHOR]