Synthesis and characterization of light‐emitting oligo(p‐phenylene‐vinylene)s and polymeric derivatives containing three‐ and five‐conjugated phenylene rings

Several series of light‐emitting oligo(p‐phenylene‐vinylene)s (BIII and BV series containing three‐ and five‐conjugated phenylene rings) with various side groups and end groups attached to the cores were synthesized and characterized. The analogous PBV polymers, derived from the BV series, were also synthesized and investigated. Blue and greenish light emissions were observed in the photoluminescence (PL) and electroluminescence (EL) spectra of the blend and pure films with these π‐conjugated structures. In contrast to the three‐conjugated ring oligomers, the five‐conjugated ring derivatives (oligomers and polymers) had larger maximum emission wavelength values of PL and EL emissions. Mesomorphism was introduced into the BV series by the replacement of three‐conjugated rings (BIII series) with five‐conjugated phenyl cores (BV series). The liquid‐crystalline properties of the BV series with end groups (on both end rings) were better than those of analogous BV‐OC₈ without end groups. Polarized PL emissions were obtained by the alignment of liquid‐crystalline phase in rubbing cells. Upon heating, different PL emission wavelengths and intensities were observed in various phases. Not only the solubility and thermal properties but also the PL and EL properties could be effectively adjusted by the attachment of flexible alkoxy groups either on the central rings or on both end rings of the conjugated cores. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 783–800, 2006     

Oriented thin films from soluble polythiophenes

The degree of orientation of thin films of eight different polymeric structures, belonging to the class of soluble polyalkylthiophenes (PATs) has been studied. Thin films of the polymers, obtained by spin coating onto glass substrates, were oriented by means of the rubbing technique. The degree of orientation is related to the regioregularity of the system: highly regioregular polymers can be oriented, while regiorandom materials are not oriented. The degree of orientation can be improved by thermal annealing of the oriented films. As a result of annealing, which was performed at different temperatures according to the thermal behavior of the polymers, it was possible to increase the polarization ratio for poly(3-decylthiophene) up to 12–13 as detected from the UV-vis spectra in polarized light. Moreover in the investigated PATs, both the key role of molecular weight and its distribution for achieving a high orientation degree has been assessed. Copyright © 2003 John Wiley & Sons, Ltd.     

Multicolor single‐layer electroluminescence device using poly(L‐glutamate) for hole transport

Helical poly(L ‐glutamate) with carbazole (Cz) side chains (PCELG) was synthesized as a hole‐transport host material for a dye‐doped polymer electroluminescence (EL) device. The main‐ and side‐chain conformations were investigated by a combination of polarized infrared spectroscopy and semiempirical quantum chemical calculation. In an electrically poled PCELG crystalline film, the main chain was found to assume a right‐handed α‐helical conformation with an order parameter of ～0.8. The Cz plane at the terminal side chain is inclined by about 44° toward the helical axis, creating a regular stacked structure conforming to the rigid α‐helical backbone. The principal EL characteristics of these devices were determined and compared with those of devices made with poly(N‐vinyl carbazole) (PVCz). For green and blue light, EL devices using PCELG exhibited luminance efficiencies comparable to those using PVCz. To the best of our knowledge, this was the first demonstration of primary colors emitted by an organic EL device with a polypeptide hole‐transport host material. The experimental results suggested that the total concentration and spatial arrangement of the Cz groups play an important role in determining the EL characteristics of dye‐doped polymer EL devices. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 496–502, 2010     

Liquid crystalline conjugated polymers and their applications in organic electronics

This article describes the syntheses and electro‐optical applications of liquid crystalline (LC) conjugated polymers, for example, poly(p‐phenylenevinylene), polyfluorene, polythiophene, and other conjugated polymers. The polymerization involves several mechanisms: the Gilch route, Heck coupling, or Knoevenagel condensation for poly(p‐phenylenevinylene)s, the Suzuki‐ or Yamamoto‐coupling reaction for polyfluorenes, and miscellaneous coupling reactions for other conjugated polymers. These LC conjugated polymers are classified into two types: conjugated main chain polymers with long alkyl side chains, namely main‐chain type LC polymers, and conjugated polymers grafting with mesogenic side groups, namely side‐chain type LC conjugated polymers. In general, the former shows higher transition temperature and only nematic phase; the latter possesses lower transition temperature and more mesophases, for example, smectic and nematic phases, depending on the structure of mesogenic side chains. The fully conjugated main chain promises them as good candidates for polarized electroluminescent or field‐effect devices. The polarized emission can be obtained by surface rubbing or thermal annealing in liquid crystalline phase, with maximum dichroic ratio more than 20. In addition, conjugated oligomers with LC properties are also included and discussed in this article. Several oligo‐fluorene derivatives show outstanding polarized emission properties and potential use in LCD backlight application. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2713–2733, 2009     

Excitation energy transfer in poly(p-phenylphenylenevinylene) determined by polarized fluorescence spectroscopy

Polarized fluorescence spectroscopy is used to investigate the photophysical behavior of poly(p-phenylphenylenevinylene) (PPPV) in polystyrene matrix in comparison with oligomeric model compounds. For this purpose PPPV is modeled by a chain consisting of a distribution of independent oligomeric segments. Excitation energy transfer (EET) between the segments depends on the wavelength of excitation, not only for transfer along an isolated polymer chain, but also for intermolecular transfer at high concentration of PPPV. The spatial range of EET, as indicated by fluorescence depolarization, is reduced for excitation at the long wavelength edge of the absorption spectrum (“red-edge-effect”). © 1995 John Wiley & Sons, Inc.     

Effect of wood flour as nucleating agent on the isothermal crystallization of poly(lactic acid)

The effect of wood flour (WF) as an efficient nucleating agent on the isothermal melt crystallization and isothermal cold crystallization behavior of poly(lactic acid) (PLA) was investigated by differential scanning calorimeter and polarized optical microscopy. It was found that the incorporation of 4 wt% WF promoted the crystallization of PLA about 4.2%. Polarized optical microscopy results showed the Maltese cross of the samples. The presence of the 4 wt% WF may increase the nucleation density, leading to the increase of the spherulites; however, the size of the spherulites decreased, and the structure became incomplete. The Avrami model was applied to analyze the isothermal crystallization kinetics. It is concluded that the addition of WF modified the crystallization process of PLA (the value of Avrami exponent changed). Various parameters, such as the crystallization half time and crystallization rate constant, reflect that 4 wt% WF significantly improves the crystallization process. The observations in this article indicate that WF is an efficient nucleating agent of PLA. Copyright © 2016 John Wiley & Sons, Ltd.     

铱配合物为核、聚对苯为枝的超支化电磷光聚合物的合成与发光性能

用Suzuki缩聚反应合成了以三-(2-间溴苯基吡啶)合铱为核,以聚2,5-二辛氧基苯为枝的超支化电磷光绿光聚合物（PPPIrppy）。 聚合物中当铱配合物摩尔分数大于0.5%时,主体的发射被完全淬灭,电致发光（EL）光谱只有位于520 nm处的绿光发射,表明主客体之间发生了有效的能量转移。 基于铱配合物摩尔分数为1％的聚合物的发光器件(器件结构：ITO/PEDOT:PSS/emissive layer/Ba/Al)在电流密度为40×10-3 A/cm2时,最大电流效率达到2.89 cd/A,器件的最大亮度达到1 689 cd/m2,色坐标为（0.34,0.59）。     

Conformational transitions and aggregations of regioregular polyalkylthiophenes

Diverse conformational transitions and aggregations of regioregular poly (3-alkylthiophene)s (PATs) in different environment have been studied by means of AFM and UV-vis-spectroscopy. In methanol, which is a non-solvent for both alkyl side groups and aromatic backbone at low polymer concentration, PATs chains fold into compact poorly ordered flat structures. At higher polymer concentration PATs molecules undergo 3D aggregation into near spherical particles. In hexane, which is a selective solvent for alkyl side chains, PATs molecules undergo ordered main-chain collapse followed by 1D aggregation. Concentration-independent red shift of λmax and good resolved fine vibronic structure in the electronic absorption spectra indicate that planarization occurs on the single-molecule level.     

Whiskers of poly(3-alkylthiophene)s

It is shown that poly(3-alkylthiophene)s may readily crystallize from poor solvents in the form of whiskers. The experimental conditions required for the formation of whiskers were found to depend upon the alkyl side-chain length, solvent quality, and temperature. In all cases studied for alkyl side-chain lengths of 3-12 carbon atoms, the widths of the whiskers were of the order of 15nm, while their lengths often exceeded tens of microns. The thickness of the whiskers formed under the experimental conditions employed was found to scale with side-chain length, and was approximately 2 or 3 times the a/2 lattice dimension of the polymer unit cell. Packing of the macromolecules within the whiskers was such that the polymer backbones were normal to the whisker length; that is, the b-axis was oriented parallel to the long axis of the whiskers. These results are thought to be relevant to known thermochromism phenomena associated with poly(3-alkylthiophene)s. © 1993 John Wiley & Sons, Inc.     

Synthesis and properties of novel poly(arylene ether)s and poly(arylene thioether)s based on a pyridazine biphenol or a phthalazine biphenol

Novel sulfur‐containing biphenol monomers were prepared in high yields by the reaction of 4‐mercaptophenol with chloropyridazine or chlorophthalazine compounds. High‐molecular‐weight poly(arylene ether)s were synthesized by a nucleophilic substitution reaction between these sulfur‐containing monomers and activated difluoro aromatic compounds. The inherent viscosities of these polymers ranged from 0.34 to 0.93 dL/g. The poly(pyridazine)s exhibited glass‐transition temperatures greater than 165 °C. The poly(phthalazine)s showed higher glass‐transition temperatures than the poly(pyridazine)s. A polymer synthesized from a bisphthalazinebiphenol and bis(4‐fluorophenyl)sulfone had the highest glass‐transition temperature (240 °C). The thermal stabilities of the poly(pyridazine)s and poly(phthalazine)s showed similar patterns of decomposition, with no significant weight loss below 390 °C. The poly(phthalazine)s were soluble in chlorinated solvents such as chloroform, and the poly(pyridazine)s were soluble in dipolar aprotic solvents such as N,N′‐dimethylacetamide. The soluble poly(pyridazine)s and poly(phthalazine)s could be cast into flexible films from solution. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 262–268, 2007     

Copoly(p‐phenylene)s containing bipolar triphenylamine and 1,2,4‐triazole groups: Synthesis,optoelectronic properties,and applications

Two novel copoly(p‐phenylene)s ( P1 – P2 ) containing bipolar groups (12.8 and 6.8 mol %, respectively), directly linked hole transporting triphenylamine and electron transporting aromatic 1,2,4‐triazole, were synthesized to enhance electroluminescence (EL) of poly(p‐phenylene vinylene) (PPV) derivatives. The bipolar groups not only enhance thermal stability but also promote electron affinity and hole affinity of the resulting copoly(p‐phenylene)s. Blending the bipolar copoly‐(p‐phenylene)s ( P1 – P2 ) with PPV derivatives ( d6‐PPV ) as an emitting layer effectively improve the emission efficiency of its electroluminescent devices [indium tin oxide (ITO)/poly(3,4‐ethylenedioxythiophene) (PEDOT):poly(styrenesulfonate) (PSS)/polymer blend/Ca (50 nm)/Al (100 nm)]. The maximum luminance and maximum luminance efficiency were significantly enhanced from 310 cd m^?2 and 0.03 cd A^?1 ( d6‐PPV ‐based device) to 1450 cd m^?2 and 0.20 cd A^?1 (blend device with d6‐PPV / P1 = 96/4 containing ～0.5 wt % of bipolar groups), respectively. Our results demonstrate the efficacy of the copoly(p‐phenylene)s with bipolar groups in enhancing EL of PPV derivatives. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Crystallization and morphology of poly(vinylidene fluoride)/poly(3‐hydroxybutyrate) blends. I. Spherulitic morphology and growth by polarized microscopy

The development of the poly(3‐hydroxybutyrate) (PHB) morphology in the presence of already existent poly(vinylidene fluoride) (PVDF) spherulites was studied by two‐stage solidification with two separate crystallization temperatures. PVDF formed irregular dendrites at lower temperatures and regular, banded spherulites at elevated temperatures. The transition temperature of the spherulitic morphology from dendrites to regular, banded spherulites increased with increasing PVDF content. A remarkable amount of PHB was included in the PVDF dendrites, whereas PHB was rejected into the remaining melt from the banded spherulites. When PVDF crystallized as banded spherulites, PHB could consequently crystallize only around them, if at all. In contrast, PHB crystallized with a common growth front, starting from a defined site in the interfibrillar regions of volume‐filling PVDF dendrites. It formed by itself dendritic spherulites that included a large number of PVDF spherulites. For blends with a PHB content of more than 80 wt %, for which the PVDF dendrites were not volume‐filling, PHB first formed regular spherulites. Their growth started from outside the PVDF dendrites but could later interpenetrate them, and this made their own morphology dendritic. These PHB spherulites melted stepwise because the lamellae inside the PVDF dendrites melted at a lower temperature than those from outside. This reflected the regularity of the two fractions of the lamellae because that of those inside the dendrites of PVDF was controlled by the intraspherulitic order of PVDF, whereas that from outside was only controlled by the temperature and the melt composition. The described morphologies developed without mutual nucleating efficiency of the components. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 873–882, 2003     

Morphology Evolution During Polymer Crystallization Simultaneous Calorimetric and Optical Measurements

The crystallization of the isotactic poly(propylene) (I-PP) has been studied carrying out measurements by means of a special calorimeter connected to a microscope and a digital acquisition system of images. To authors' knowledge, this is the first time that simultaneous calorimetric and optical measurements are carried out on polymers. The analysis of Polarized Optical Microscopy images has allowed the appraisal of nucleation density and growth rate in isothermal and non isothermal conditions. The results obtained in isothermal conditions have been analyzed through the Kolmogoroff model and the crystallinity calculated from the model has been compared with that obtained from the calorimetric measurements.     

Occurrence of Both Sinusoidal and Zigzag Supermolecular Structures Associated with Band Textures in a Liquid Crystalline Polymer

Band textures are observed in a precipitation film from a presheared poly(1,4-phenylene terephthalamide) solution, a typical lyotropic main-chain polymeric liquid crystal. By polarized optical microscopy (POM) studies and in the same specimen system, both sinusoidal and zigzag supermolecular structures associated with band textures are found, according to the comparison between the experimental micrographs and the theoretical birefringence patterns. As a consequence, the present paper describes how to distinguish these two supermolecular structures merely by POM and demonstrates that both structure models are reasonable. © 1997 John Wiley & Sons, Ltd.     

Ionic complexes of biosynthetic poly(malic acid) and poly(glutamic acid) as prospective drug-delivery systems

The hydrolytic degradability and erythromycin release from stoichiometric ionic complexes of biotechnological poly(beta,L-malic acid)s and poly(gamma,D-glutamic acid)s with alkyltrimethylammonium surfactants were investigated. The influence of pH, temperature and antibiotic load on hydrolysis rate was examined. It was found that poly(malic acid) complexes degraded by a surface erosion mechanism at a higher rate than poly(glutamic acid) complexes, which eroded in bulk. Erythromycin was lodged in the paraffinic subphase of the complexes and upon aging it was delivered according to a sigmoidal profile that appeared to be independent on the antibiotic load.     

Studies on thermotropic liquid crystalline polymers. XV. Synthesis and properties of liquid crystalline copoly(imide-ester)s

Three series of the thermotropic liquid crystalline copoly(imide-ester)s were prepared by direct polycondensation. The first two series of the copoly(imide-ester)s were synthesized from N-(4-carboxyphenyl) trimellitimide with N,N-di(hydroxypropyl) pyromellitic diimide and various aromatic diols. The third series of copoly(imide-ester)s were prepared by N-(4-carboxyphenyl) trimellitimide with various imide-diols (methylene spacer = 2–6) and phenyl hydroquinone. The structures and thermal properties of the synthesized poly(imide-ester)s were examined by FTIR spectrum, wide-angle x-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermal optical polarized microscope, and thermogravimetric analysis (TGA). The effects of the structures of the aromatic diols on the thermal properties of the resulting copoly(imide-ester)s were investigated. It was found that most of the copoly(imide-ester)s possessed excellent mesophase stabilities and thermostabilities. The mesophase stabilities of poly(imide-ester)s decreased with the increase of the size of lateral group, and the mesophase range increased with the increase of the amount of PhHQ. No significant odd-even effects were observed between the methylene spacer lengths and transition temperatures. © 1996 John Wiley & Sons, Inc.     

内含C60掺杂空穴传输层的量子点电致发光器件

聚乙烯咔唑（PVK）中掺入富勒烯（C₆₀）的重量比从0%到10%变化,以研究在空穴传输层中掺杂C₆₀后对量子点电致发光器件性能的影响。掺入C₆₀后的PVK薄膜在氧化铟锡（ITO）基底上均方根粗糙度从3nm降至1.6nm。另外,掺入C₆₀后有利于空穴的注入和传输,改善器件中电子和空穴的平衡,提高了器件的效率。     

Effect of poly(vinyl alcohol) fine particles as a novel biodegradable nucleating agent on the crystallization of poly(3‐hydroxybutyrate)

The effect of poly(vinyl alcohol)(PVA) fine particles as the nucleating agent on the crystallization behavior of bacterial poly(3‐hydroxybutyrate)(PHB) was studied using differential scanning calorimetry measurements and polarized light microscope observation. The results were compared with the effect of PVA conventionally blended with PHB. The PVA fine particles were found to be able to greatly enhance the crystallization of PHB, while the conventionally blended PVA extremely retarded the crystallization of PHB. The nucleating effect of PVA fine particles is almost comparable to that of the talc powder. Considering the biodegradability and biocompatibility of PVA, the usage of PVA particle as a nucleating agent provides marked benefits over the currently employed nonbiodegradable nucleating agents, such as talc and boron nitride. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44:1813–1820, 2006     

内含C_(60)掺杂空穴传输层的量子点电致发光器件

聚乙烯咔唑(PVK)中掺入富勒烯(C60)的重量比从0%到10%变化,以研究在空穴传输层中掺杂C60后对量子点电致发光器件性能的影响。掺入C60后的PVK薄膜在氧化铟锡(ITO)基底上均方根粗糙度从3 nm降至1.6 nm。另外,掺入C60后有利于空穴的注入和传输,改善器件中电子和空穴的平衡,提高了器件的效率。     

Poly(N-phenyl-2-hydroxytrimethylene amine): Its blends with poly(ϵ-caprolactone) and water-soluble polyethers

A new polymer with pendant hydroxyl groups, namely, poly(N-phenyl-2-hydroxytrime-thylene amine) (PHA), was synthesized by a direct condensation polymerization of aniline and epichlorohydrin in an alkaline medium. The new polymer is amorphous with a glass transition temperature (T_g) of 70°C. Blends of PHA with poly(ϵ-caprolactone) (PCL), as well as with two water-soluble polyethers, poly(ethylene oxide) (PEO) and poly(vinyl methyl ether) (PVME), were prepared by casting from a common solvent. It was found that all the three blends were miscible and showed a single, composition dependent glass transition temperature (T_g). FTIR studies revealed that PHA can form hydrogen bonds with PCL, PEO, and PVME, which are driving forces for the miscibility of the blends. © 1997 John Wiley & Sons, Inc.