INFLUENCE OF TRACES OF WATER ON THE SYNTHESIS AND ELECTROLUMINESCENCE PROPERTIES OF POLY(2-METHOXY, 5- (2' -ETHYLHEXYL OXY)- 1, 4-PHENYLENE VINYLENE)

It was found that traces of water in the reaction medium would result in a great increase of gel and a decrease of Molecular weight of the poly(2-methoxy,5-(2'-ethylhexyloxy)-1,4-phenylene vinylene) during the polymerization, which ultimately led to inferior film qualities and device properties. The device (ITO/PEDOT/MEH-PPV/Ba/Al) with MEH-PPV prepared under dry conditions has an external quantum efficiency of above 2.0%.

Effect of Chemical Doping and Ion Implantation on Cond uctivity of Poly(p-phenylene vinylene) Derivatives

The surface conductivity of poly [ 2-methoxy-5-（3＇-methyl） butoxy]-p-phenylene vinylene （PMOMBOPV） films doped with FeCl3 and H2SO4 by chemical method and implanted by N^＋ ions was studied and the comparison of environmental stability of conductive behavior was also investigated. The energy and dose of N^＋ ions were in the rang 15～35 keV and 3. 8×10^15～9. 6×10^16 ions/cm^2, respectively. The conductivity of PMOMBOPV film was enhanced remarkably with the increases of the energy and dose of N^＋ ions. For example, the conductivity of PMOMBOPV film was 3. 2×10^-2S/cm when ion implantation was performed with an energy of 35 keV at a dose of 9. 6 × 10^14 ions/cm^2 , which was almost seven orders of magnitude higher than that of film unimplanted. The environmental stability of conductive behavior for ionimplanted film was much better than that of chemical doped films. Moreover, the conductive activation energy of ion-implanted films was measured to be about 0.17 eV.

The Synthesis and Electronic Characteristics of Poly(p-Phenylene Vinylene) Derivatives

A series of soluble poly(p-phenylene vinylene) (PPV) derivatives were synthesized through dehydrochlorination with the p-metaoxy phenol as starting materials. The electronic characteristics of PPV derivatives were studied.

NOVEL HYPERBRANCHED POLY(PHENYLENE OXIDE)S WITH PHENOLIC TERMINAL GROUPS: EFFECTS OF REACTION TIME AND CORE MOLECULES ON THE MOLECULAR WEIGHT AND POLYDISPERSITY

A novel hyperbranched poly（phenylene oxide） （HPPO） with phenolic terminal groups was prepared from 4-bromo-4＇,4＂-dihydroxytriphenylmethane as AB2 monomer in dimethylsulfoxide （DMSO） via a modified Ullmann reaction. The molecular weight and polydispersity （PD） of the resulting polymers increased with increasing reaction time. In the presence of core molecules （bisphenol A and 1,3,5-trihydroxybenzene）, which have the similar molecular backbones to the reactive monomer, the molecular weight could be controlled by varying the core-to-monomer ratio. Incorporation of a very small amount of core molecules could lead to a higher molecular weight as compared with that without the addition of core molecules. However, when the core content reached certain extent, the molecular weight would decrease with the further increase in the core content. A new similar behavior of control over the PD was also obtained. The resulting polymers were characterized by ^1H-NMR, ^13C-NMR, FT-IR, and GPC.

The Synthesis and Characterization of High Molecular Weight Poly(phenylene sulfide/ether)

Poly（phenylene sulfide/ether） （PPSE） was synthesized from 4,4＇-dihydroxydiphenyl sulfide and 4,4＇-dichlorodiphenyl sulfide in solution by nucleophilic substitution reaction. The resulting polymer was characterized by viscosity measurement, elemental analysis, FT-IR, ^1H NMR, X-ray diffraction and thermal analysis. The results showed that the viscosities of the resulting polymer were above 0.68 dL/g, and the linear chain structure of product was confirmed. PPSE had the same reflex indices as poly（p-phenylene sulfide）, an orthorhombic crystalline with unit cell a=0.853, b=0.562, c=1.026nm. The melting temperature, glass transition temperature and initial decomposition temperature were found to be 228℃, 85℃ and 325℃, respectively. The product was soluble in common organic solvents such as NMP, N, N＇-dimethylformamide, N, N＇-dimethylacetamide and 1,2-dichloroethane.

CRYSTAL STRUCTURE AND MORPHOLOGY OF NASCENT SAMPLES OF SYMMETRIC AROMATIC POLYESTERS——Ⅰ.POLY(P-PHENYLENE TEREPHTHALATE)

The morphology and crytal structure of poly(p-phenylene terephthalate) (PPT), prepared by confined thin filmmelt (CTFMP) and solution (CTFSP) and bulk solution polymerization, were characterized by transmission electronmicroscopy, electron dimaction and molecular modeling. The unit cell is monoclinic (P2_1/a space group) with parameters a =7.89, b = 5.49, c = 12.65 A, α=γ= 90°, β=100.33°, density = 1.48 g/cm^3, the a, b and β values differing slightly from thosereported previously in the literature. A degree of variation in relative intensities of hk0 reflections in, apparently, untilted[001] ED patterns was observed from a given sample, suggesting some variation in molecular packing. ED evidence wasfound for a second phase, with [001] appearing the same as for phase Ⅱ of the related poly(p-oxybenzoate) (PpOBA)polymer. CTFMP crystals polymerized above 220℃ (up to 370℃) and CTFSP crystals polymerized at 300℃ consisted oflamellae 100-200 A thick.

The Insulator-to-Conductor Transition in Sulphonated Poly(Phenylene Oxide)Polymer membranes:Percolation Theory Approach

In this paper the percolation theory is employed to study the insulator-to-conductortransition in sulphonated poly（phenylene oxide）（SPPO） polymer membranes.The membranes withdifferent sulphonation degree were prepared and infrared characterized.The transition thresholdwas calculated by the experimental data of membrane conductivities and the coordination numberwas thus estimated.The functional group-SO3H distribution in the membrane was evaluated inaccordance with the calculations and showed a non-random dispersion on the microscopic scale.

SYNTHESIS AND MORPHOLOGICAL STRUCTURE OF POLY (PHENYLENE SULFIDE AMIDE)

Poly(phenylene sulfide amide) (PPSA) has been synthesized by using sulfur as S source which reacts with dichlorobenzamide (DCBA) and alkali in polar organic solvent at the atmospheric pressure. The polymer structures were determined by elemental analysis, FT-IR and H-1-NMR. It is shown that the yielded polymer has linear structure and its structure unit is -p-C6H4-CONH -p-C6H4-S-. The polymer morphology was studied by X-ray diffraction and polarized microscopy. The results show that PPSA is a crystalline polymer and its spherulites are the aggregation of nontwisting lamella or micro-thread structure. Under shearing force, these crystals are dispersed to form micro-fibrillar structure. The decomposition kinetics of PPSA was also studied at different heating rates. The decomposition energy of PPSA is higher than that of PPS.

GAS SORPTION AND TRANSPORT IN POLY (PHENYLENE OXIDE)(PPO)AND ARYL-BROMINATED PPO MEMBRANES

The apparent solubility (S), concentration-average diffusivity (D), and permeability (P), for C0_2, CH_4 and N_2 through PPO and aryl-brominated PPO at 35℃ for pressure ranging from 1 to 26 atm are reported. It is found that P, D, and S of the membranes to all the three gases vary with the extent of bromination. S increases with the increase of the percent of bromine in each case, but D to CO_2 increases remarkably only at higher degree of brominafion, and therefore, P to CO_2 is increased by more than 100% over a wide range ofpressure in the case. The solubility data are well described by the dual mode sorption model. It is found that the gas molecules sorbed by the Langmuir mode are relatively more immobilized and the contribution of the nonequilibrinm character of the polymer to gas permeation increases obviously for CO_2 and is hardly changed for CH_4 with increasing bromine content. These observations are interpreted in terms of changes in specific free volume (SFV)and the cohesive energy density (CED) of the polymers.

EFFECT OF SOLVENT COMPOSITION ON THE SULFONATION DEGREE OF POLY(PHENYLENE OXIDE) (PPO)

This paper investigates the possibility of attaining sulphonated poly(phenylene oxide) (SPPO) with a relativelyhigher sulfonation degree. To achieve this aim, the approach we adopt is to improve the solubility of the final product in themixed solvent so that the sulfonation may take place between the bulk solutions and PPO powders even at higher sulfonationdegree. It is shown that the addition of a proper amount of dimethyl formide (DMF) to the conventional PPO-chloroformsystem can actually enhance the sulfonation effect. The solvent composition is then correlated with the sulfonation degreebased on the solubility parameters. It is interesting to find that solubility parameters between the mixed solvent and theprecipitated products keep an approximately unchanged value at about 4.9, which is just equal to that when pure chloroformis used, though the solubility parameters of both solvents increase with the content of DMF in solution. This may be the mainreason why the addition of DMF can reduce the precipitation and improve the ion exchange capacity (IEC) of SPPOpolymer.

Poly(meta-phenylene) Derivative with Rigid Twisted Biphenyl Units in Backbone:Synthesis,Structural Characterization,Photophysical Properties and Electroluminescence

A soluble poly（meta-phenylene） derivative with rigid twisted biphenyl unit was synthesized by the Yamamoto coupling reaction. The polymer is soluble in common organic solvents, and the number-average molecular weight is about 6500. The UV-Vis and quantum chemical calculation indicate that the different conformation segments named ＂conformers＂ exist in the polymer backbones; it was also further confirmed by the single crystal X-ray diffraction study of the dimeric model compound. The π-π^＊ transition of biphenyl segments of twisted and planar conformations made the polymer exhibit a strong absorption around 256 nm and a weak absorption at about 300 nm. Furthermore, the polymer exhibits a strong UV photoluminescence at 372 nm when the excitation wavelengths are longer than 300 run. The ultraviolet-emitting electroluminescence（EL） device with the single layer structure shows EL λmax of the derivative at 370 nm.

SYNTHESIS OF SOLUBLE POLY(3-HEXYL-2,5-THIENYLENE VINYLENE) FROM THIOPHENE

Soluble poly(3-hexyl-2,5-thienylene vinylene) (PHTV) was readily synthesized from thiophene in a yield better than that of the precursor method to prepare poly(thienylene vinylene) (PTV). The bandgap of the polymer is about 1.8 eV, which is comparable with that of PTV. Owing to the introduction of alkyl side groups onto the backbone of the polymer, it can be dissolved in common organic solvents such as chloroform, THF and toluene. The synthesis of soluble PHTV is a very important approach to preventing oxidation and to improving the properties and the processbility of the PTV. The existence of alkyl side groups in PHTV does not affect its, bandgap and thermal properties as compared with PTV. After doping with FeCl3, the conductivity of PHTV is as high as 1.1 x 10(-2) S/cm. The soluble PHTV can be easily transformed into thin film with much better quality than that of the PTV film prepared by the traditional precursor method, which is very important for fabricating devices with good properties.

Effect of Curing Poly(<i>p</i>-Phenylene Sulfide) on Thermal Properties and Crystalline Morphologies

Commercial poly(p-phenylene sulfide) (PPS) was thermally cured, which resulted in an increase of molecular weight due to cross-linking. Non-isothermal crystallization studies of samples cured for up to 7 days at 250?C showed a monotonous increase of crystallization temperature compared to pure PPS. However, a further increase of curing time decreased the crystallization temperature. The change in the half-crystallization time (t1/2) was similar to the crystallization temperature. Thus, the cross-linking of PPS affected crystallization behaviors significantly. To a certain extent, crosslinks acted as nucleation agents, but excessive cross-linking hindered the crystallization. Morphologies observed by polarized optical microscopy suggested that thermal curing for as little as 1 day contributed to the spherulitic structure having a smaller size, that was not observed with pure PPS.

Preparation of Poly (Phenylene Sulfide Amide) by Sulfur Solution Route

A new process for preparing poly(phenylene sulfide amide, PPSA), which is by reaction of sulfur instead of sodium sulfide as S source with dichlorobenzamide (DCBA) and alkali in polar organic solvent at the atmospheric pressure (called sulfur solution route), is reported in the present paper. The influences of polymerization time, molar ratio of precursors, catalyst and solvent upon the polymer were investigated. To seek the best parameters of polymerization, orthogonal design was employed in the experiments. The results indicate that the molar ratio of precursors is the most significant effect on both of viscosity and yield of the polymer. The suitable parameters for preparing the related polymer are presented. The polymer was characterized by IRspectrum, 1HNMRspectrum and Raman spectrum, etc.

Synthesis and Characterization of Poly(1-methoxy-4-octyloxy)-Para-Phenylene Vinylen for Light-Emitting Diodes Application

In this study, the conjugated polymer, poly(1-methoxy-4-octyloxy)-para-phenylene vinylene (MO-p-PPV) was synthesized and characterized. MO-p-PPV was synthesized according to Gilch polymerization mechanism by using 4-methoxyphenol as starting material in the presence of potassium tert-butoxide (1M in THF). The product was further purified by multiple precipitations in different solvents such as methanol, tetrahydrofuran, isopropyl alcohol and hexane. The final product was dried to afford MO-p-PPV as a red solid. The resulting polymer was completely soluble in common organic solvents. The structure of monomer and optical properties of polymer were characterized by proton nuclear magnetic resonance (1H-NMR) spectroscopy, UV-vis spectroscopy, and fluorescence spectroscopy. The UV-vis spectrum showed absorption maxima for MO-p-PPV at 491 nm. Similarly, fluorescence spectrum showed λmax emission at 540 nm.

Thermal Stability Improvement and Structural Change of Oil Gels Formed by Styrene-Butadiene-Styrene Triblock Copolymer Induced by Adding Poly(phenylene ether)

The thermal stability of oil gels formed by styrene-butadiene-styrene triblock copolymer (SBS) was improved by adding a small amount of poly(phenylene ether) (PPE), which has a higher glass transition temperature (Tg). In naphthenic oil which is a good solvent for the butadiene blocks, but a non-solvent for the styrene blocks and PPE, PPE was selectively included into styrene blocks in SBS, and induced the increase of the Tg of these blocks. The melting temperature determined by viscoelastic measurements and softening temperature of the gels were elevated by adding PPE, while no significant change was detected by adding polystyrene. The gel became opaque by adding PPE, and partially separated phases were observed by field emission scanning electron microscopy (FE-SEM). The dependence of the viscoelastic behavior on the PPE concentration can be explained by the structural change observed by FE-SEM.

RAMAN SPECTROSCOPIC STUDY ON THE CHAIN CONFORMATION OF ELECTROSYNTHESIZED POLY(ρ-PHENYLENE)FILMS

Poly（p-phenylene） （PPP） films have been electrochemically deposited on mirrorlike stainless steel （SS） electrode surfaces by direct oxidation of benzene in boron trifluoride diethyl etherate （BFEE） solutions at a constant applied potential of 1.7 V （versus Ag/AgCl）. The chain conformations of as-grown PPP films have been studied by Raman spectroscopy. The results demonstrated that high synthesis temperature favors the formation of planar PPP, and the conformation of planar PPP can be changed into torsional PPP by cooling treatment.

ELECTRICALLY CONDUCTIVE COMPOSITE PREPARED BY ELECTROCHEMICAL POLYMERIZATION OF PYRROLE IN POLY-(p- PHENYLENE TEREPHTHALAMIDE) MATRIX

The preparation of PPy/PPTA conductive composite films by electrochemical method is presented.The first step is to cast a thin layer of poly (p-phenylene-terephthalamide) (PPTA) on a slice of Pt working electrode. The second step is to electrochemically polymerize pyrrole on the PPTA/Pt working electrode. Both of the electrical conductivity and the mechanical properties of the PPy/PPTA composite film are better than those of the pure PPy film, and the film has excellent flexibility at low temperature, even in liquid nitrogen.The SEM picture of the cross-section of PPy,/PPTA composite film showed that the two components were well mixed.Cyclic voltammograms of PPy,/PPTA film in aqueous solution showed that the conductive films could be reduced and reoxidized.

Synthesis,Characterization,and Linear and Nonlinear Optical Properties of Phenylene-vinylene Based Chromophores for Singlet Oxygen Generation

A series of symmetrical and unsymmetrical phenylene-vinylene （PV） based chro- mophores with the molecular configuration of donor-π-donor （D-g-D） were prepared and characterized. Iodine was first introduced into the Jr-conjugation backbone of the PV based chromophores in order to study the heavy atom effect on their linear absorption, two-photon absorption （TPA） properties, as well as singlet oxygen generation properties. TPA cross-sections of these chromophores were investigated by using the two-photon excited fluorescence method. The unsymmetrical chromophores were found to have larger TPA cross-section values compared to their symmetrical counterparts. For one of the unsymmetrical chromophores with the iodine incorporation, a large TPA cross section value with quenched emission was found. The decreased fluorescence quantum yield of a molecule can be ascribed to the increased intersystem crossing, which is favorable for enhancing the singlet oxygen generation. Therefore, the unsymmetrical PV based chromophores with heavy atom incorporation are promising singlet oxygen sensitizers for the photodynamic therapy application.