The synthesis and thermotropic liquid crystalline behavior of the novel poly(aryl ether ketone)s containing chloro-side group

The novel poly(aryl ether ketone)s containing chloro-side group were synthesized by nucleophilic substitution reactions of 4,4'-biphenol and chlorohydroquinone with either 4,4'-difluorobenzophenone(BP/CH/DF) or 1,4-bis(p-fluorobenzoyl)benzene (BP/CH/BF) and their thermotropic liquid crystalline properties were characterized by a variety of experimental techniques. The thermotropic liquid crystalline behavior was observed in the copolymers containing 50 and 70% biphenol. Melting transition (Tm) and isotropization transition (Ti) both appeared in the DSC thermograms. A banded texture was formed after shearing the sample in the liquid crystalline state. The novel poly(aryl ether ketone)s had relatively higher glass transition temperature (Tg) in the range of 168 similar to 200 degrees C and lower melting temperature (Tm) in the range of 290 similar to 340 degrees C. The thermal stability (Td) was in the range of 430 similar to 490 degrees C.

Studies on water-swellable elastomers .2. Thermal properties and crystalline behavior of amphiphilic graft copolymers with poly(ethylene glycol) side chains

The thermal properties and crystalline structure of the amphiphilic graft copolymers CR-g-PEG600, CR-g-PEG2000, and CR-g-PEG6000 using chloroprene rubber (CR) as the hydrophobic backbone and poly(ethylene glycol) (PEG) with different molecular weights as the hydrophilic side chains were studied by DSC and WAXD. The results showed that a distinct phase-separated structure existed in CR-g-PEGs because of the incompatibility between the backbone segments and the side-chain segments. For all the polymers studied, T-m2, which is the melting point of PEG crystalline domains in CR-g-PEG, decreased compared to that of the corresponding pure PEG and varied little with PEG content. For CR-g-PEG600 and CR-g-PEG2000, T-m1, which is the melting point of the CR crystalline domains, increased with increasing PEG content when the PEG content was not high enough, and at constant PEG content, the longer were the PEG side chains the higher was the T-m1. The crystallite size L-011 of CR in CR-g-PEGs increased compared to that of the pure CR and decreased with increasing PEG content. (C) 1997 John Wiley & Sons, Inc.

Studies on the fusion heat of poly(ether ether ketone ketone)-poly(ether biphenyl ether ketone ketone) copolymers

On the basis of DSC measurements, the Delta H-f(0) values of the fusion heat for PEEKK-PEBEKK copolymers with various biphenyl contents were obtained by using thermodynamics statistical theory proposed by Flory and graphical method of the specific volume-fusion heat. The results reveal that Delta H-f(0) values determined by these two methods for PEEKK-PEBEKK copolymers with various biphenyl content are nearly the same, and that Delta H-f(0) values are closely dependent on biphenyl content. Delta H-f(0) value is minimum at n(B)=0.35.

Miscibility and phase behavior in blends containing random copolymers of poly(ether ether ketone) and phenolphthalein poly(ether ether ketone)

The miscibility and phase behavior of polysulfone (PSF) and poly(hydroxyether of bisphenol A) (phenoxy) with a series of copoly(ether ether ketone) (COPEEK), a random copolymer of poly(ether ether ketone) (PEEK), and phenolphthalein poly(ether ether ketone) (PEK-C) was studied using differential scanning calorimetry. A COPEEK copolymer containing 6 mol % ether ether ketone (EEK) repeat units is miscible with PSF, whereas copolymers containing 12 mol % EEK and more are not. COPEEK copolymers containing 6 and 12 mol % EEK are completely miscible with phenoxy, but those containing 24 mol % EEK and more are immiscible with phenoxy. Moreover, a copolymer containing 17 mol % EEK is partially miscible with phenoxy; the blends show two transitions in the midcomposition region and single transitions at either extreme. Two T(g)s were observed for the 50/50 blend of phenoxy with the copolymer containing 17 mol % EEK, whereas a single composition-dependent T-g appeared for all the other compositions. An FTIR study revealed that there exist hydrogen-bonding interactions between phenoxy and the copolymers. The strengths of the hydrogen-bonding interactions in the blends of the COPEEK copolymers containing 6 and 12 mol % EEK are the same as that in the phenoxy/PEK-C blend. However, for the blends of copolymers containing 17, 24, and 28 mol % EEK, the hydrogen-bonding interactions become increasingly unfavorable and the self-association of the hydroxyl groups of phenoxy is preferable as the content of EEK units in the copolymer increases. The observed miscibility was interpreted qualitatively in terms of the mean-field approach. (C) 1996 John Wiley & Sons, Inc.

Structural study on poly(ether ether ketone ketone)-poly(ether biphenyl ether ketone ketone) copolymers

Structures of poly(ether ether ketone ketone)-poly(ether biphenyl ether ketone ketone) copolymers were studied by using small angle X-ray scattering and the one-dimensional electron density correlation function method. The results revealed that structures of the aggregated state of the copolymers depend closely on the biphenyl content (n(b)). When n(b) = 0.35, invariant Q, long period L, average thickness of crystal lamellae (d) over bar, electron density difference eta(c) - eta(a) and degree of crystallinity W-c,W-x assume minimum values.

Synthesis and properties of block copolymers of poly(ether sulphone)s with liquid crystalline polyester units

Block copolymers of poly(ethersulphone) (PES) oligomers with liquid crystalline polyester units were synthesized by the reaction of dihydroxy-terminated poly(ether sulphone) oligomers (number-average molecular weights: 704, 1,158 and 2570) and terephthaloyl bis(4-oxybenzoyl chloride), and their properties were investigated. The results indicated that the copolymer with PES segments of molecular weight of 704 possessed birefringent features when annealed at 360 degrees C, while the copolymer with PES segments of molecular weight of 2,570 became isotropic. Also, the block copolymers had a better chemical resistance and high-temperature stability than PES.

GLASS-TRANSITION AND CRYSTALLIZATION OF POLY(VINYL ALCOHOL)-G-POLY(METHYL METHACRYLATE) GRAFT-COPOLYMERS

The glass transition behaviour, microphase separation morphology and crystallization of poly(vinyl alcohol)-g-poly(methyl methacrylate) graft copolymers (PVA-g-PMMA) were studied. A lamellar microphase separation morphology was formed, even for a copolyme

The Heterogeneous Growth of P(3MeTh)--An Ellipsometric Study

Successive thicker P(3MeTh) layers are analysed by ex situ conventional and imaging ellipsometry. Thin films display a smooth surface, are compact and homogeneous while for a growth charge above 20 mC cm(-2) the polymer structure modifies to a still uniform but less dense layer. A two-layer model is used and a mathematical procedure is developed to obtain, simultaneously, from the experimental ellipsometric parameters, Delta and Psi, the thickness and the complex refractive index of P(3MeTh) films grown up to 80 mC cm(-2). Thicker polymer layers are disordered and present a high degree of surface roughness. 

Hybrid bulk heterojunction solar cells from a blend of poly(3-hexylthiophene) and TiO2 nanotubes

Hybrid bulk heterojunction solar cells based on blend of poly(3-hexylthiophene) (P3HT) and TiO2 nanotubes or dye(N719) modified TiO2 nanotubes were processed from solution and characterized to research the nature of organic/inorganic hybrid materials. Compared with the pristine polymer P3HT and TiO2 nanoparticles/P3HT solar cells, the TiO2 nanotubes/P3HT hybrid solar cells show obvious performance improvement, due to the formation of the bulk heterojunction and charge transport improvement. A further improvement in the device performance can be achieved by modifying TiO2 nanotube surface with a standard dye N719 which can play a role in the improvement of both the light absorption and charge dissociation. Compared with the non-modified TiO2 nanotubes solar cells, the modified ones have better power conversion efficiency under 100 mW/cm(2) illumination with 500W Xenon lamp. (C) 2008 Elsevier B. V. All rights reserved.

Fabrication of ZnO and its enhancement of charge injection and transport in hybrid organic/inorganic light emitting devices

ZnO nanocrystals were synthesized by hydrolysis in methanol. X-ray diffraction and photoluminescence spectra confirm that good crystallized ZnO nanoparticles were formed. Utilizing those ZnO nanoparticles and poly [2- methoxy-5 - (3',7'-dimethyloctyloxy)- 1,4-phenylenevinylene] (MDMO-PPV), light emitting devices with indium tin oxide (ITO)/poly(3,4-oxyethyleneoxy-thiophene):poly(styrene sulfonate) (PEDOT:PSS)/ ZnO:MDMO-PPV/Al and ITO/PEDOT:PSS/MDMO-PPV/Al structures were fabricated. Electrolummescence (EL) spectra reveal that EL yield of hybrid MDMO-PPV and ZnO nanocrystals devices increased greatly as compared with pristine MDMO-PPV devices. The current-voltage characteristics indicate that addition of ZnO nanocrystals can facilitate electrical injection and charge transport. The decreased energy barrier to electron injection is responsible for the increased efficiency of electron injection. (c) 2007 Elsevier B.V. All rights reserved.

Electropolymerized poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) film on ITO glass and its application in photovoltaic device

Poly(3,4-ethylenedioxythiopliene):poly(styrene sulfonate) (PEDOT:PSS) films have been electrochemically polymerized in situ on ITO glass substrate in boron trifluoride diethyl etherate electrolyte (BFEE). Cyclic voltammograms show good redox activity and stability of the PEDOT films. These films had been directly used to fabricate organic-inorganic hybrid solar cells with the structure of ITO/PEDOT/ZnO:MDMC-PPV/Al. The solar cells made of electrochemically polymerized films exhibit higher energy conversion efficiencies compared with that prepared by the spin-coating method, and the highest value is 0.33%. This in-situ electropolymerized method effectively simplifies fabricating procedures and may blaze a facile and economical route for producing high-efficiency solar cells.

RTCVD工艺制备poly-Si薄膜太阳电池的研究

报道了快速热化学气相沉积(RTCVD)工艺制备多晶硅(poly -Si)薄膜及电池的实验和结果。采用SiH_2Co_2作为原料气体，衬底温度为1030℃时，薄膜的生长速率为10nm/s。发现薄膜的平均晶粒度及载流子迁移率与衬底温度和材料有关。用该薄膜在未抛光重掺杂磷的硅衬底上制备1cm~2的p~+n结样品电池，无减反射涂层，其转换效率为4.54%(AM1.5,100mW/cm~2,25℃)。

Synthesis and luminescence properties of hybrid organic-inorganic transparent titania thin film activated by in-situ formed lanthanide complexes

Stable transparent titania thin films were fabricated at room temperature by combining thenoyltrifluoroacetone (TTFA)-modified titanium precursors with amphiphilic triblock poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO, P123) copolymers. The obtained transparent titania thin films were systematically investigated by IR spectroscopy, PL emission and excitation spectroscopy and transmission electron microscopy. IR spectroscopy indicates that TTFA coordinates the titanium center during the process of hydrolysis and condensation. Luminescence spectroscopy confirms the in-situ formation of lanthanide complexes in the transparent titania thin film.

A strategy for synthesis of ion-bonded amphiphilic miktoarm star copolymers via supramolecular macro-RAFT agent

Amphiphilic supramolecular miktoarm star copolymers linked by ionic bonds with controlled molecular weight and low polydispersity have been successfully synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization using an ion-bonded macromolecular RAFT agent (macro-RAFT agent). Firstly, a new tetrafunctional initiator, dimethyl 4,6-bis(bromomethyl)-isophthalate, was synthesized and used as an initiator for atom transfer radical polymerization (ATRP) of styrene to form polystyrene (PSt) containing two ester groups at the middle of polymer chain. Then, the ester groups were converted into tertiary amino groups and the ion-bonded supramolecular macro-RAFT agent was obtained through the interaction between the tertiary amino group and 2-dodecylsulfanylthiocarbonylsulfanyl-2-methyl propionic acid (DMP). Finally, ion-bonded amphiphilic miktoarm star copolymer, (PSt)(2)-poly(N-isopropyl-acrylamide)(2), was prepared by RAFT polymerization of N-isopropylacrylamide (NIPAM) in the presence of the supramolecular macro-RAFT agent. The polymerization kinetics was investigated and the molecular weight and the architecture of the resulting star polymers were characterized by means of H-1-NMR, FTIR, and GPC techniques. (c) 2008 Wiley Periodicals, Inc.

Synthesis and Properties of Carbazole Main Chain Copolymers with Oxadiazole Pendant toward Bipolar Polymer Host: Tuning the HOMO/LUMO Level and Triplet Energy

Three new carbazole copolymers, poly(9-(2,5-diarene-[1,3,4]oxadiazole)-carbazole-alt-9-(2-ethylhexyl)-carbazole-3,6-diyl)s (P1), poly(9-(2,5-diarene-[1,3,4]oxadiazole)-2, 7-carbazole-alt-9-(2-ethylhexyl)-3, 6-carbazole-diyl)s (P2), and poly(9-(2,5-diarene-[1,3,4]oxadiazole)-carbazole-alt-9-(2-ethylhexyl)-carbazole-2,7-diyl)s (P3), were synthesized by the Suzuki coupling reaction