Determination of purity and molecular weight of calmodulin by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

The purity and molecular weight of calmodulin have been determined by means of matrix-assisted laser desorption/ionization time of flight mass spectrometry, and the results have been discussed. The experimental results demonstrate that this method is high sensitive and rapid as compared with other traditional methods.

Stimulated emission in blue wavelength region from a copolymer

A dye laser based on the soluble conjugated polymer, Poly[1,8-octanedioxy-2,6-dimethoxy-1,4-phenylene-1,2-ethenylene-1, 4-phenylene-1,2-ethenylene-3,5-dimethoxy-1,4-phenylene], has been fabricated. The laser was pumped by light pulses from the third harmonic radiation of an Nd:YAG laser. The lasing was observed in the blue wavelength region with the peak at 450 nm. The threshold energy is about 19 mu J. The energy conversion yield of the laser is about 3.4%. The maximum peak power of the laser output pulse arrives at about 20 kW.

Synthesis of poly(phenylenesulfidephenylenamine) by self-polycondensation of methyl-(4-anilinophenyl) sulfide with antimony pentachloride

Poly(phenylenesulfidephenylenamine)(PPSA) an alternating copolymer and the hybrid structure of poly(phenylene sulfide)(PPS) and polyaniline(PAn), was synthesized by self-polycondensation of methyl-(4-anilino-phenyl) sulfide with antimony pentachloride and by the acid-induced self-polycondensation of methyl-(4-anilino-phenyl) sulfoxide.

Luminescence enhancement by blending PVK with blue PPV copolymer

The PL and EL properties of the polymer blends of PVK and blue PPV copolymer were studied. Considerable enhancement of both the photoluminescent and the electroluminescent intensity were observed by using the polymer blends as emission layer in the LED devices. The energy transfer process and the formation of exciplex in the polymer blends were also discussed.

Synthesis and enhancement of quantum efficiency of a series of novel PPV derivative copolymers

A series of novel PPV derivative copolymers with good solubility in common organic solvents were synthesized. The emitting color of these copolymers could range from red to blue by adjusting the structures and the compositions of monomers. Investigation on their optical properties showed that the PL quantum efficiency could be increased by energy transfer and conjugation reduction. The PL quantum efficiency of most green/blue copolymer films on slide glass was higher than 80%.

Bright green organic electroluminescent devices based on a novel thermally stable terbium complex

A navel thermally stable terbium carboxylate complex, Tb(MTP)(3)(phen) (MTP=monotetradecyl phthalate, phen=1,10-phehanthroline), was synthesized and characterized. The device structure of glass substrate/indium-tin-oxide/poly(p-phenylenevinylene) (PPV)/poly (N-vinycarbazole) (PVK):Tb(MTP)(3)(phen): 1,3,4-oxadizole derivative (PBD)/tris(8-hydroxyquinoline) (Alq(3))/aluminum (Al) was employed to study the electroluminescent properties of Tb(MTP)(3)(phen). A green emission with extremely sharp spectral band of less than 10 nm at 544 nm peak wavelength was observed. A maximum luminance of 152 cd/m(2) and an external quantum efficiency of 0.017% were achieved at a drive voltage of 24 V. A possible mechanism of energy transfer based on the polymer doped with lanthanide organic complex was also proposed.

Conductive polyaniline poly-omega-aminoundecanoyle blending fiber

Conductive fibers were obtained by blending polyaniline with poly-omega-aminoundecanoyle in-concentrated H2SO4 Micro-fiber caused by non-compatibility between the two polymers was valuable for improving conductive property of the fibers. Abnormal effect on the crystallinity of polyaniline and poly-omega-aminoundecanoyle upon drawing stress was observed.

Preparation and properties of water-based conducting polyaniline

A convenient way to make water-soluble or water-dispersible conducting polyaniline was given by employing protonic acid dopants containing hydrophilic ethyleneoxide oligomer as counter-anion. The conducting polyaniline possessed electrical conductivity in the range of 10(-3) to 10(-2) S/cm, depending on the dopant, and it displayed excellent electrochemical redox reversibility in non-aqueous system.

Polyaniline as marine antifouling and corrosion-prevention agent

Conductive polyaniline was found to have special marine antifouling property. The coating from conducting polyaniline and epoxy resin(or polyurethane) can last 6-9 months in Southern China sea, i.e., less than 10% of the coating surface was fouled during this period. The conducting polyaniline has special synergetic antifouling effect on other antifouling agents like cuprous oxide or 4, 4'-dichlorodiphenyltrichloroethane. The conductivity of the polyaniline was found to be extremely important for its antifouling effect. Moreover, employing aliphatic polyamine as solvent of emeraldine base and curing agent of epoxy resin, a new technique to process corrosion prevention coating containing emeraldine base was developed, therefrom the emeraldine base and epoxy resin was in molecular level blending. This technique was solvent free and extremely effective, i.e., only 1wt% of emeraldine base in the coating can have good corrosion prevention property.

Water soluble polyaniline and its blend films prepared by aqueous solution casting

Polyaniline (PAn) was doped with phosphonic acid containing hydrophilic tails. The solubility of the doped PAn in water was controlled by changing the length of hydrophilic chain in the dopant. When poly(ethylene glycol) monomethyl ether (PEGME) with molecular weight M-w = 550 was used as the hydrophilic chain of the dopant, the doped PAn was entirely soluble in water. The film cast from aqueous solution showed good electrochemical redox reversibility, Aqueous solution blending of PAn with poly(ethylene glycol) (PEG, M-w = 20 000) and poly(N-vinyl pyrrolidone) (PVP, M-w = 360 000) was achieved. Percolation threshold of the composite film was lower than 3 wt.%. Electrical conductivity of the composite film was in the range of 10(-1)-10(-5) S cm(-1), depending on molecular weight of the acid and the content of PAn in the composite. (C) 1999 Elsevier Science Ltd. All rights reserved.

Processible nanostructured materials with electrical conductivity and magnetic susceptibility: Preparation and properties of maghemite polyaniline nanocomposite films

We here present a versatile process for the preparation of maghemite/polyaniline (gamma-Fe2O3/ PAn) nanocomposite films with macroscopic processibility, electrical conductivity, and magnetic susceptibility. The gamma-Fe2O3 nanoparticles are coated and the PAn chains are doped by anionic surfactants of omega-methoxypoly(ethylene glycol) phosphate (PEOPA), 4-dodecylbenzenesulfonic acid (DBSA), and 10-camphorsulfonic acid (CSA). Both the coated gamma-Fe2O3 and the doped PAn are soluble in common organic solvents, and casting of the homogeneous solutions gives free-standing nanocomposite films with gamma-Fe2O3 contents up to similar to 50 wt %. The morphology of the gamma-Fe2O3 nanoparticles are characterized by transmission electron microscopy, UV-vis spectroscopy, and X-ray diffractometry. The gamma-Fe2O3/PAn films prepared from chloroform/m-cresol solutions of DBSA-coated gamma-Fe2O3 and CSA-doped PAn are conductive (sigma = 82-237 S/cm) and superpapamagnetic, exhibiting no hysteresis at room temperature. The zero-field-cooled magnetization experiment reveals that the nanocomposite containing 20.8 wt % gamma-Fe2O3 has a blocking temperature (T-b) in the temperature region of 63-83 K.

Soluble 2,5-dimercapto-1,3,4-thiadiazole/poly(o-toluidine) electroactive composite

A poly(o-toluidine) (POT)/2,5-dimercapto-1,3,4-thiadiazole (DMcT) composite was prepared. When POT and DMcT are mixed in a proper solvent, POT in a medium-oxidation state is reduced, and DMcT in turn is oxidized to its soluble dimer when the molar ratio of DMcT to POT is higher than 0.5. Therefore, the composite was soluble in organic solvents such as tetrahydrofuran (THF), dimethylformamide (DMF), and N-methyl-2-pyrrolidone (NMP) and exhibited very high electroactivity, two orders of magnitude higher than that of pure POT and three orders of magnitude higher than that of pure DMcT. Molecular-level contact between POT and DMcT is the reason for the improved catalytic effect of POT on DMcT, compared to that of polyaniline on DMcT. (C) 1999 The Electrochemical Society. S0013-4651(98)08-059-8. All rights reserved.

The effect of preparation conditions on the catalyst Nd(P-507)(3)/H2O/Al(i-Bu)(3) for the polymerization of styrene

The catalyst system neodymium phosphonate Nd(P-507)(3)/H2O/Al(i-Bu)(3) for the polymerization of styrene was examined. Effects of the addition order of the catalyst components, catalyst aging time and aging temperature on the catalyst activity and the polymer characteristics were investigated. The catalyst activity for isospecific polymerization of styrene increases with aging time and reaches the maximum with a catalyst aged for 45 min at 70 degrees C. The aging time that the catalyst needs to reach the highest activity for isospecific polymerization decreases with increasing aging temperature. The preformed catalyst and the in situ catalyst were compared with respect to the kinetic behavior of the styrene polymerization and the polymer characteristics.

Catalytic oxidization polymerization of aniline in an H2O2-Fe2+ system

Polyaniline is prepared by chemical polymerization of aniline in an acidic solution using H2O2 as an oxidant and ferrous chloride as a catalyst. A wide variety of synthesis parameters are studied, such as the amount of the catalyst, reaction temperature, reaction time, initial molar ratio of oxidant, monomer and catalyst, and aniline and HCl concentrations. The polymerization of aniline can be initiated by a very small amount of catalyst. The yield and the conductivity of product depend on the initial molar ratio of the oxidant and monomer. The polyaniline with a conductivity of about 10 degrees S/cm and a yield of 60% is prepared under optimum conditions. The process of polymerization was studied by in situ ultraviolet-visible spectroscopy and open-circuit potential technology. Compared to the polymerization process in a (NH4)(2)S2O8 system, the features of the H2O2-Fe2+ system are pointed out, and the chain growth mechanism is proposed. (C) 1999 John Wiley & Sons, Inc.

Enzymatic degradation of poly(epsilon-caprolactone)/poly(DL-lactide) blends in phosphate buffer solution

Blend films of poly(epsilon-caprolactone) (PCL) and poly(DL-lactide) (PDLLA) with 0.5 weight fraction of PCL were prepared by means of solution casting and their degradation behavior was studied in phosphate buffer solution containing Pseudomonas (PS) lipase. Enzymatic degradation of the blend films occurred continuously within the first 6 days and finally stopped when the film weight loss reached 50%, showing that only PCL in the blends degraded under the action of PS lipase in the buffer solution. These results indicate the selectivity of PS lipase on the promotion of degradation for PCL and PDLLA. The thermal properties and morphology of the blend films were investigated by differential scanning calorimetry, wide-angle X-ray diffraction and scanning electron microscopy (SEM). The morphology resulting from aggregate structures of PCL in the blends was destroyed in the enzymatic degradation process, as observed by SEM. These results confirm again the enzymatic degradation of PCL in the blends in the presence of PS lipase. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.