掺杂DCJTB聚合物电化学池（LEC）的发光性质

通过在聚合物电化学池(LEC)发光器件的发光材料MEH-PPV中掺杂红光染料DCJTB,对LEC器件的发光性质进行研究。基于器件结构为ITO/MEH-PPV PEO LiCF3SO3/Al的薄膜LEC器件,其电致发光峰在570nm左右,通过在MEH-PPV与PEO的混合膜中掺杂不同比例的红光染料DCJTB,随着掺杂比例的增加,器件的发光峰由570nm向红光波段移动,通过控制DCJTB的掺杂比例制备了发光峰在570~650nm连续变化的LEC电致发光器件。对其分析认为从LEC主体发光聚合物MEH-PPV到染料DCJTB间发生了良好的能量传递。     

白光二极管用Ba3MgSi2O8基质发光材料的溶胶雾化-微波烧成与光谱性质

分别采用溶胶雾化-微波烧成工艺和高温固相法制备了用于白光发光二极管的Ba3MgSi2O8∶Eu,Mn,Al荧光粉。溶胶雾化-微波烧成两步法制备的样品物相纯度和结晶度都比较高,具有中心位置437,500,608nm的三色发射带。在375nm紫外光激发下,发光的色坐标为x=0.3253,y=0.2134,相关色温7391K,可得到预期的白光发射。其中蓝、绿两个发射带分别来自于Ba3MgSi2O8和Ba2SiO4晶格中Ba2 格位的替位原子Eu2 的5d-4f跃迁,红光发射带源于Ba3MgSi2O8中Mn2 的4T-6A跃迁发射。红光的激发谱与蓝光的激发谱几乎重合,可以确定在Ba3MgSi2O8∶Eu,Mn,Al发光过程中存在着从蓝光发射中心到红光发射中心的能量传递。但是,与通常的共振能量传递模型不同,蓝光发射谱与红光激发谱之间并没有明显的光谱重叠。相比之下,高温固相法样品没有观察到红光发射,这一方面是由于生成的Ba2SiO4中杂相较多,激发光很大一部分被Ba2SiO4晶格中的Eu2 绿光发光中心吸收,传递到Mn2 红光发光中心的能量减少;另一方面与固相法中Mn2 在Ba3MgSi2O8晶格中掺杂困难有关。     

可调白光发射的Ce-Tb-Eu共掺钙硼硅酸盐发光玻璃

采用高温熔融法制备了Eu单掺和Ce-Tb-Eu共掺的钙硼硅酸盐发光玻璃。使用荧光分光光度计测量了样品的发射与激发光谱,并通过激发、发射光谱和CIE色度坐标对其发光特性进行了研究。结果表明:改变玻璃基质提高其光学碱度,可以大幅度增加Eu³⁺/Eu²⁺比例,增强Eu³⁺的红光发射。在378 nm单色光激发下,Ce-Tb-Eu共掺发光玻璃的发射光谱中同时观测到了蓝光、绿光和较强的红光特征峰。通过调节Tb、Eu的比例,可以使样品发射光谱的色坐标在白光区域内变化,实现白光调控。     

高效、色度稳定的顶发射白光有机发光二极管

顶发射白光有机发光二极管(white organic light-emitting diodes,WOLEDs)因可与有源驱动电路结合实现大开口率和高分辨率,因而在白光照明和全彩显示中有着良好的应用前景.本文制备了红/蓝双磷光发光层的顶发射WOLEDs,通过在红光层与蓝光层间插入电子阻挡层tris(phenypyrazole)iridium(Ir(ppz)3),降低了对红光掺杂浓度的要求,红光掺杂浓度的提高不仅降低了对制备工艺的要求,提高了工艺可重复性,而且改善了WOLEDs的效率与色度稳定性。分析了色度稳定的原因,优化了红光和蓝光磷光客体的掺杂浓度,制备出发光效率达到7.9cd·A-1的顶发射WOLED,其色坐标位于暖白光区,在87~2 402cd·m-2亮度范围内色度很稳定,仅变化(0.006,0.01)。     

新型有机电致磷光白光器件的研究

制备了结构为ITO/NPB/TCTA/FIrpic∶TCTA/Ir(MDQ)2(acac)∶TmPyPB/FIrpic∶TmPyPB/TmPyPB/LiF/Al的有机电致磷光发光器件。通过在双蓝光发光层之间插入较薄的红光层Ir(MDQ)2(acac)∶TmPyPB调节载流子、激子在各发光层中的分布,并结合TCTA和TmPyPB对发光层内载流子和激子的有效阻挡作用,混合实现白光发射。研究了红光层在不同厚度、不同掺杂浓度下对器件发光性能的影响。结果表明,红光发光层厚度为2nm、质量浓度为5%时,结合蓝光发光层和红光发光层,实现了色坐标为(0.333,0.333)、最大发光效率为11.50cd/A的白光发射。     

Sr5-x（PO4）2SiO4∶xEu2+磷灰石荧光粉的发光性能及LED应用研究

采用高温固相法在还原气氛下合成了Sr5-x(PO4)2SiO4∶xEu2+磷灰石型荧光粉。通过XRD、PL、SEM对样品的晶体结构、激发和发射光谱以及形貌进行了表征。在Eu2+浓度较低时,Eu2+占据不同的晶体格位而形成两个发光中心,发射光谱具有双发射峰;随着掺杂浓度的增加,Eu2+之间的能量传递使黄光区域的发射峰强度逐步增强,并在x=0.075时达到最大值。发射光谱红移可能是Eu2+受晶场强度和能量传递共同作用的结果。考察了该材料在白光LED中的封装应用性能,其双发射峰有助于提升白光LED光源的显色性。     

4,4,4-三氟-1-(4'-间三联苯基)-1,3-丁二酮邻菲咯啉铕(Ⅲ)配合物的合成与发光

合成了新的配合物EuL3phen,[HL=4,4,4-三氟-1-(4’-间三联苯基)-1,3-丁二酮,phen=邻菲咯啉]。采用元素分析,红外光谱,质谱对该配合物的结构进行了表征。该化合物在半导体InGaN芯片发出的近紫外光激发下,发出铕(Ⅲ)离子5D0—7FJ(J=0~4)跃迁特征红光,最大发射峰位于613 nm,发光量子效率为13%。配合物寿命为470μs,寿命曲线很好地和单指数衰减拟合曲线相吻合。配合物热稳定性达到220℃,满足制备LED器件的要求。将配合物EuL3phen和半导体395 nm发射InGaN芯片组合,成功地制备了红色发光二极管。发光二极管的色坐标、发光效率、配合物和硅胶质量比相关,在配合物和硅胶质量比为1∶25时,器件色坐标为x=0.64,y=0.35,光效为0.89 lm.W-1。该配合物是充当制作白光LED用的潜在的红色发光组分。     

蓝光发射和红光发射多孔硅的XPS分析

绿色发光多孔硅在空气中经两种不同的氧化处理分别得到红色发光和蓝色发光.X射线光电子能谱分析显示红色发光多孔硅中含有一定比例的Si、SiOx(x=1～2)以及少量的氟化物;蓝色发光多孔硅的主要成份是SiO2及少量的氟化物.红处透射谱显示蓝光发射多孔硅几乎只存在Si-O-Si峰,而红光发射多孔硅除主要有Si-O-Si峰外,还有明显的SiHx峰.分析表明多孔硅中的蓝光发射来源于SiO2中的缺陷中心.     

一种基于荧光材料的聚合物白光发光二极管

制备了一种基于荧光聚合物共混的单发光层聚合物白光发光二极管.器件结构为铟锡氧化物/苯磺酸掺杂聚乙烯基二氧噻吩/发光层/ 1,3,5-三(N-苯基-2-苯并咪唑-2)苯41/Ba/Al,蓝光材料芴-氟化喹喔啉共聚物(PF-BPFQ5)、绿光材料苯基取代的聚对苯乙炔(P-PPV)和红光材料聚(2-甲氧基-5-(2′-乙基己氧基)-1,4-对苯乙炔)(MEH-PPV)共混为发光层.当PF-BPFQ5,P-PPV,MEH-PPV的质量比例为100∶06∶06时,获得标准的白光,色坐标为（033 关键词： 聚合物发光二极管 白光 共混     

均苯三甲酸Eu-Tb配合物的合成及荧光性质研究

以H3BTC为配体,用水热法合成了均苯三甲酸Eu-Tb系列发光配合物Eu1-xTbxBTC.nH2O(H3BTC=1,3,5-均苯三甲酸,x=0,0.1,0.3,0.5,0.7,0.9,1.0;n=0,0.5),通过化学分析及元素分析确定了配合物的组成,用红外光谱对其进行了表征;研究了配合物的激发光谱和发射光谱,并就其荧光强度与两种稀土离子含量之间的关系进行了讨论。结果表明:(1)该系列配合物(除纯均苯三甲酸Tb外)均发出Eu离子的特征荧光,而荧光强度随着Eu和Tb离子的不同发生了明显变化,发射峰位置基本不变;(2)系列配合物中Tb对Eu的荧光强度有敏化作用,Eu对Tb的荧光强度有猝灭作用;同时Eu离子的5D0→7F1和5D0→7F2跃迁发射强度较强,且均劈裂为两个峰(587,593 nm)及(611.2,618 nm),这是由于Eu离子所处的配位环境不同所引起的。     

Thermal studies on ethylene–vinylcyclohexane copolymers prepared with bis-indenyl type metallocene catalyst systems

Ethylene–vinylcyclohexane copolymers (EVCH) were synthesized with unsubstituted and substituted bis-indenyl type metallocene catalysts and their thermal and dynamic mechanical behavior was studied and compared to a series of metallocene catalyzed ethylene-1-hexene (EH) and ethylene-1-hexadecene (EHD) copolymers. Increasing comonomer incorporation in the chain decreased the melting point, the level of crystallinity, and the density of all copolymers, but the bulky size of the vinylcyclohexane (VCH) group made this decrease very insignificant for the EVCH copolymers. The influence of the VCH group was also noticed in the loss tangent curves by dynamic mechanical analysis as a very insignificant shift of the β-transition to lower temperatures at increasing comonomer content, a behavior quite opposite to the behavior of the EH and EHD copolymers. The storage modulus curves explained that the stiffness properties of the EVCH copolymers are as good or better than those of the EH and EHD copolymers at the same comonomer level. The intensities of the maximum in the loss tangent curves indicate that EVCH copolymers may have good impact properties. Fractionation studies by differential scanning calorimetry (DSC) using a self-nucleation/annealing (SSA) procedure confirmed a broadening of the lamellar thickness distribution as the amount of comonomer increased. Self-nucleation/annealing curves of highly branched EVCH and EH copolymers exhibited big similarities suggesting similar random comonomer distributions.     

Preparation and properties of sulfonated polybenzimidazole-polyimide block copolymers as electrolyte membranes

Sulfonated polybenzimidazole-polyimide block copolymers are synthesized through condensation polymerization at high temperature. The length of the polyimide chain is varied to give a series of block copolymers with various block lengths. The as-synthesized block polymers are used to prepare the corresponding membranes through the solvent evaporation method. The structure of the block copolymers is characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR). Their mechanical strength, thermal behavior, water uptake, swelling ratio, and proton conductivity, as well as oxidative stability are also investigated. All the block copolymers exhibit good thermal stability, dimensional stability, mechanical strength, and proton conductivity. Compared to the random sulfonated polyimide-containing benzimidazole membranes with the same degree of sulfonation, the membranes prepared from the block copolymers show higher proton conductivities. The proton conductivities of the block copolymer membranes range from 6.2?×?10^?4 to 1.1?×?10^?2?S cm^?1 at 105 °C. The block copolymer membrane doped with phosphoric acid exhibits proton conductivity higher than 0.2 S cm^?1 at 160 °C, indicating its potential applications in proton exchange membrane fuel cells operated under high temperature and low humidity conditions.     

Tetramethylpolyarylate-polyarylate block copolymer: Synthesis and miscibility with polyarylate and poly(styrene-co-acrylonitrile)

Abstract

Tetramethylpolyarylate-polyarylate (TMPAr-PAr) block copolymers of various block lengths were synthesized by the coupling reaction of hydroxy-terminated TMPAr and hydroxy-terminated PAr using triphosgene. The phase behavior of these block copolymers are discussed based on the thermal properties observed by differential scanning calorimetry (DSC). The thermal properties of binary blends of these block copolymers with PAr homopolymer or poly(styrene-co-acrylonitrile) whose acrylonitrile content is 9.5 wt% (SAN 10) were observed by DSC. The compatibilizing effect of the microphase-separated TMPAr-PAr block copolymer in PAr/SAN 10 blends was observed from thermal properties and morphology.     

Mössbauer studies of acrylonitrile/alkyl methacrylate copolymers doped with ferric chloride

Acrylonitrile/methyl methacrylate (A/M), acrylonitrile/ethyl methacrylate (A/E) and acrylonitrile/n-butyl methacrylate (A/B) copolymers containing ferric chloride were prepared by free radical bulk polymerization. TGA studies show that the addition of ferric chloride increases the thermal stability of these copolymers. Mössbauer studies of the copolymers showed the presence of Fe³⁺ species only. Mössbauer spectra of the copolymer heated at 200°C, 350°C and 500°C did not show a reduction of the Fe³⁺ species, and α-Fe₂O₃ was the final product formed.     

Mössbauer studies of solid state decomposition of methyl methacrylate-ethyl methacrylate copolymers containing ferric chloride

Methyl methacrylate (MMA)-ethyl methacrylate (EMA) copolymers of different monomer concentrations containing anhydrous ferric chloride were prepared by bulk polymerization at 70°C. TGA studies showed that inclusion of iron salt increases the thermal stability of copolymers by 50°C. Mössbauer spectra of copolymers heated at different temperatures showed the presence of Fe³⁺ species only, in different environments. The mechanism of thermal stabilization of copolymer has been proposed on the basis of IR, TGA and Mössbauer spectroscopy studies.     

Starch Graft Copolymers: Novel Applications in Industry

Starch, which is a natural carbohydrate biopolymer, has been the subject of academic and industrial studies for many decades, basically due to its low cost, biodegradability and versatility of use. Chemical modification of starch by grafting various monomers onto it imparts increased hydrophilicity, hydrophobicity or polyelectrolyte nature to starch depending on the reagent and conditions used. The starch graft copolymers are synthesized by the free radical initiated reaction of starch with acrylic monomers in presence of a free radical initiator such as ceric ammonium nitrate. High viscosity, thermal stability, biodegradability, good film forming properties and water absorption capacity are some of the properties shown by the graft copolymers of starch. Graft copolymers find various applications in industry as flocculants, waste water treatment and heavy metal ion removal, for sizing cotton, as mulch films, in oil drilling, as biodegradable polymers and in superabsorbents. Starch graft copolymers are also gaining increasing importance in the manufacture of molded plastics, ion-exchange resins, plastic films and in cosmetics. Non-biodegradable plastic waste is an ecological threat. Use of starch as an extender and replacement of synthetic polymers-based hydrogels is currently an active research area. Incorporation of starch into other synthetic polymers not only reduces our dependence on petrochemical derived monomers but also provides materials in which the starch portion can biodegrade rapidly in the environment.     

Ultrasonic degradation of poly (styrene-co-alkyl methacrylate) copolymers

The ultrasonic degradation of poly (styrene-co-methyl methacrylate) (SMMA), poly (styrene-co-ethyl methacrylate) (SEMA) and poly (styrene-co-butyl methacrylate) (SBMA) copolymers of different compositions was studied. The copolymers were synthesized and NMR spectroscopy was used to determine the composition, and the glass transition temperatures were determined by DSC. The reactivity ratios were determined by the Kelen–Tudos method and it indicated that the copolymers were random. The effect of solvent, temperature and copolymer composition on the ultrasonic degradation rate of these copolymers was investigated. A model based on continuous distribution kinetics was employed to study the degradation kinetics. The degradation rate coefficients of the copolymers decreased with an increase in the styrene content in the copolymer. At any particular copolymer composition the rate of degradation follows the order: SBMA > SEMA > SMMA. Thermogravimetric analysis (TGA) of the copolymers was carried in order to assess their thermal stability. The same order of degradation was observed for the thermal degradation of the copolymers as that observed for ultrasonic degradation.     

Thermal behavior of vinylidene chloride—methyl acrylate copolymers

The thermal behavior of random copolymers of vinylidene chloride-methyl acrylate (VDC-MA) was monitored with differential scanning calorimetry. The effects of composition, annealing, and heating rate on the copolymer melting process were studied. Increasing levels of comonomer decreased the crystalline melting point and percent crystallinity of the copolymers. A combination of information obtained from heating rate and small-angle x-ray scattering studies led to a model of the melting behavior of PVDC and its copolymers. Apparently a simultaneous melting/recrystallization phenomenon occurs in these materials during heating.     

Localized and long-distance charge hopping in fresh and thermally aged conductive copolymers of polypyrrole and polyaniline studied by combined TSDC and dc conductivity

The charge trapping centers in fresh and thermally aged conductive polyaniline-polypyrrole copolymers (starting from pure polyaniline and ending in pure polypyrrole by steps of 10 wt%) were studied by thermally stimulated depolarization current (TSDC) spectroscopy and dc conductivity measurements. One low temperature (115-135 K) relaxation mechanism appears in polyaniline-rich copolymers and disappears after thermal anneal. It is attributed to polaron trapping in the vicinity of chlorine anion dopants. Another relaxation mechanism operates close to room temperature and is related to conformational relaxation, which corresponds to the influence of the annihilation of the conformons on the conduction mechanism. The relaxation is sensitive to thermal aging as a result of the thermal annealing on the conductivity. The temperature derivative of the dc conductivity supports the latter assertion. The activation energy values were obtained as a function of composition for both fresh and heated samples. The TSDC spectroscopy is a sensitive tool which is an alternative to the standard conductivity studies for the characterization of polypyrrole-polyaniline conductive copolymers and the study of the thermal degradation.