聚芴材料低能级发射现象及其机理研究现状

聚芴是一类重要的蓝光发射材料,有高亮度、高效率等优点;然而聚芴类材料在发光器件中使用一段时间之后,光致发光光谱在530～550 nm、电致发光光谱在2.2～2.3e V的区域出现新的发射带,使得器件的发射变成绿光或蓝绿光,在色度失纯的同时,器件的发光效率也迅速降低.本文概述了目前提出的有关聚芴材料低能级发射形成的原因的假说、试验依据、理论计算、以及基于假说所提出的消除低能级发射、改善材料发射稳定性的方法等研究现状.     

侧链接枝低聚对亚苯基亚乙烯基聚芴衍生物的合成及其电致发光性能

采用Wittig-Horner反应,将少量端基为磷脂的黄光发射客体低聚对亚苯基亚乙烯基链段(MOPV)接枝到含有醛基单体的蓝光发射主体材料聚芴的侧链上,合成了一种新型的接枝聚芴衍生物PF-g-MOPV.这种接枝聚合物具有很好的热稳定性,可溶于常用的有机溶剂.以接枝共聚物PF-g-MOPV为发光层的单层器件发射出黄绿光,色坐标为(0.30,0.57),最大发光亮度达到1550cm/m2,这说明蓝光聚芴主链向侧链MOPV进行了有效地能量转移.     

芴类蓝光材料的长波发射问题研究进展

有机电致发光技术在通信、信息、显示和照明等领域显现出巨大的商业应用前景, 十几年来一直是光电信息领域的研究热点之一. 相对于无机电致发光材料, 有机电致发光材料具有许多优点. 芴作为一种具有刚性平面联苯结构的化合物, 由于具有宽的能隙、高的发光效率和结构上易于修饰等特点, 是一类受到各方面广泛关注的蓝光材料. 芴类蓝光材料的一个缺点是薄膜在空气中退火或器件在长时间运行后会出现长波发射, 严重影响其综合电致发光性能. 目前认为是由分子间激基缔合物、芴酮或者两者共同作用引起了该长波发射. 经过各方努力, 芴类蓝光材料的长波发射问题趋向于被完全解决. 本文结合自己的工作, 从材料合成的角度综述了国内外在研究芴类蓝光材料的长波发射问题方面所取得的进展, 并对下一步需要研究的热点问题作了展望.     

含抗氧化受阻胺的三聚芴有机半导体的合成及其光谱稳定性的研究

芴基电致蓝光材料低能绿光带(LEEB)的起源仍没有结论,其中芴酮诱导LEEB是重要机制之一,基于此我们提出通过引入含抗氧化的受阻胺来抑制LEEB的策略.通过复杂二芳基芴(CDAF)方式构建了一个共价键联接的含四甲基哌啶(TMP)的蓝光三聚芴有机半导体材料DF-PTMPF,并通过退火实验研究对其光谱稳定性的影响.研究结果表明DF-PTMPF的光谱稳定性有了很大提高,退火120h时的绿光指数φ为1.4(φ=IGreen/IBlue),而相同条件下的三聚芴TDHF的绿光指数φ为2.4.同时,由于受阻胺可以除掉体系中微量的氧,而DF-PTMPF在起初的氮气气氛下退火24h仍产生绿光带,这一结果暗示了聚集诱导LEEB仍不能忽视.     

芴酮对聚醚侧链聚芴体系的影响: 合成, 表征及光物理性质的研究

利用Yamamoto聚合反应, 通过调节单体2,7-二溴9,9'-二-(三乙氧基甲基)芴和2,7-二溴芴酮的比例, 合成了侧链为极性聚醚链, 芴酮含量逐渐增加的聚芴系列. 通过聚合物溶液及固态薄膜的紫外荧光谱图, 深入研究芴酮作为能量受体的能量转移过程及其对聚合物光物理性质的影响. 结果表明: 稀溶液中体系呈现聚芴本征态的荧光发射, 能量转移对溶液浓度具有依赖性; 固态薄膜中能量转移效率随芴酮含量的增加而快速增长, 退火后这种现象更加明显.     

含噻吩单元的硅芴共聚物的合成及其蓝色电致发光性能

将少量(摩尔分数为1%—3％)含噻吩的窄带隙单体和宽带隙硅芴单体进行共聚, 合成了聚{9,9-二己基-3,6-硅芴-co-[2,5-二(2-甲基苯撑-4-基)-噻吩]}和聚{9,9-二己基-3,6-硅芴-co-[2,5-二(2-苯撑-4-基)-噻吩]}两类硅芴共聚物, 通过紫外-可见吸收光谱、光致发光光谱, 并制作聚合物发光二极管器件测试电致发光光谱等手段, 系统表征了两类硅芴共聚物材料的性能. 实验结果表明, 噻吩的加入形成了新的蓝色发光中心, 并且实现了从硅芴链段到含噻吩发光中心的有效能量转移. 通过增加发光中心结构的空间位阻来减小其共轭程度, 可以使聚合物的PL和EL光谱发生较大蓝移. 最终得到了效率为0.46%和色坐标(CIE)为(0.19, 0.16)的蓝光LED器件.     

三苯基吡啶-芴交替共轭聚合物的合成与光致发光性能研究

通过Suzuki偶合反应得到了两种间位连接的三苯基吡啶同分异构体和9,9-二辛基芴的交替共聚物PFOTPP1和PFOTPP2.并对它们的紫外-可见吸收光谱、光致发光光谱以及电化学性能等进行了初步研究.结果表明,将间位连接的三苯基吡啶基引入聚芴主链能使聚合物的LUMO能级降低,光致发光光谱发生蓝移,得到了两种有望应用于电致炼光发光器件的共轭聚合物蓝光发光材料.     

绿色单峰发光聚(9,9-二烯丙基芴)的合成及其发光机制

为了得到绿色单峰发光的聚合物材料, 我们设计并合成了9位取代的二烯丙基芴单体, 在NiCl₂的催化下, 合成了可溶的聚芴衍生物, 聚(9,9-二烯丙基芴)(PAF). 较短的烯丙基链既可以增加聚芴的溶解度, 双键的存在又有利于聚芴发生分子间聚集而得到绿光发射的有机电致发光器件(OLED). PAF在溶液和薄膜状态下的荧光峰分别位于403和456 nm的蓝光区域, 而其器件ITO/PEDOT:PSS/PAF/LiF/Al(其中, ITO为氧化铟锡, PEDOT为聚(3,4-乙撑二氧噻吩), PSS为聚苯乙烯磺酸盐)的电致发光峰却红移至绿光区域(532 nm), 得到绿色单峰发光. 紫外吸收光谱、荧光发射光谱、红外光谱以及原子力显微镜(AFM)图像的结果证明, 造成PAF电致发绿光的机制为聚合物分子间聚集.     

聚芴类蓝光材料抑制链簇集及绿光发射的新进展

在共轭聚合物研究领域,聚芴是一类非常有前途的蓝光材料,针对其分子链易簇集及发光过程中易产生绿光等问题,本文对最近三年以来聚芴类发光材料的研究进展进行了综述.     

聚芴类共轭聚合物(PFs)从溶液到薄膜凝聚态演变过程中的定量构效关系

聚芴（polyfluorenes，PFs）是一类具有高荧光效率和良好热稳定性的经典蓝光共轭聚合物.本研究组近年来集中于聚芴类共轭聚合物溶液中单链构象-聚集态结构-薄膜凝聚态结构-器件性能间的定量构效关系研究，利用静/动联用激光光散射等表征手段，结合标度率研究方法，对PFs成膜前体溶液复杂的单链和聚集的形态结构进行了系统的研究.结合光谱与电镜等方法，揭示出PFs在溶液中孤立单链、凝聚态结构、β构象及其过渡态结构形成的动力学过程、机理及规律，构建出成膜前体溶液单链构象-薄膜中链构象-器件性能之间的定量构效关系.旨在从高分子本征性质入手，提高其光电效率.本研究不仅对聚芴类高分子，而且对整个共轭聚合物类材料的设计与加工都将具有重要的指导意义.     

Rapid micropatterning of mesoporous silica film by site-selective low-energy electron beam irradiation

Rapid microfabrication of mesoporous silica film at low temperature was achieved with low-energy electron beam (LEEB) irradiation. A mesostructured film (thickness approximately 200 nm), which was prepared through hydrolysis and condensation of tetramethoxysilane in the presence of hexadecyltrimethylammonium chloride, was irradiated with LEEB at 25 kV and 300 microA under pressures of 10 and 1000 Pa. The surfactant molecules can be eliminated completely at temperatures less than 40 degrees C after only 10 min (10 Pa) and 5 min (1000 Pa) of irradiation, resulting in conversion to a highly ordered mesoporous silica film without cracking. The LEEB-irradiated film also showed reasonable chemical resistance toward dilute hydrofluoric acid solution due to sufficient consolidation by cross-linking of silicate networks during the irradiation. The unirradiated regions were etched away preferentially to the irradiated areas; therefore, rapid micropatterning of the mesoporous silica film was possible by area-selective LEEB irradiation followed by chemical etching.     

Supercritical Carbon Dioxide Isolation of Cellulose Nanofibre and Enhancement Properties in Biopolymer Composites

The physical properties, such as the fibre dimension and crystallinity, of cellulose nanofibre (CNF) are significant to its functional reinforcement ability in composites. This study used supercritical carbon dioxide as a fibre bundle defibrillation pretreatment for the isolation of CNF from bamboo, in order to enhance its physical properties. The isolated CNF was characterised through zeta potential, TEM, XRD, and FT-IR analysis. Commercial CNF was used as a reference to evaluate the effectiveness of the method. The physical, mechanical, thermal, and wettability properties of the bamboo and commercial CNF-reinforced PLA/chitin were also analysed. The TEM and FT-IR results showed the successful isolation of CNF from bamboo using this method, with good colloidal stability shown by the zeta potential results. The properties of the isolated bamboo CNF were similar to the commercial type. However, the fibre diameter distribution and the crystallinity index significantly differed between the bamboo and the commercial CNF. The bamboo CNF had a smaller fibre size and a higher crystallinity index than the commercial CNF. The results from the CNF-reinforced biocomposite showed that the physical, mechanical, thermal, and wettability properties were significantly different due to the variations in their fibre sizes and crystallinity indices. The properties of bamboo CNF biocomposites were significantly better than those of commercial CNF biocomposites. This indicates that the physical properties (fibre size and crystallinity) of an isolated CNF significantly affect its reinforcement ability in biocomposites. The physical properties of isolated CNFs are partly dependent on their source and production method, among other factors. These composites can be used for various industrial applications, including packaging.     

Unified study of the different physical properties of amorphous polymers

Uptil now it has not been possible to explain the different physical properties of amorphous polymers using a model based on a single conceptual scheme. In this paper, a phenomenological model is proposed which tries to explain the mechanical, optical and thermal properties (both thermal conductivity and expansivity) of amorphous polymers. The model has similarities with the composite model, proposed by the present authors, which has proved to be successful in interpreting the different physical properties of semicrystalline polymers. The present model considers the bulk form of the polymer as an aggregate of microscopic units possessing intrinsic physical properties. On drawing, the development of anisotropy in different physical properties is supposed to be due to the development of preferred orientation of these units. The development of the preferred orientation has been estimated directly from birefringence data. The agreement between the calculated and experimental values of the elastic modulus, thermal conductivity and thermal expansivity of PVC, PMMA and PS is found to be reasonable good.     

Physical properties of aqueous blend of diethanolamine and sarcosine: experimental and correlation study

In this work, physical properties such as density, refractive index and viscosity of aqueous diethanolamine sarcosinate (DEA-SAR) solution were measured at different temperatures. The knowledge of physical properties is necessary for the process design and simulation of acid gas absorber plant. Various concentrations of aqueous DEA-SAR solutions (0.05, 0.10, 0.15, 0.20, 0.25 and 0.30) were investigated at temperature ranging from 298.15 to 333.15 K. The reported results showed an increment behavior in the physical properties with the increase in concentration isothermally, and a decreasing one with the rise in temperature of the solution at any given concentration. Empirical models were applied to correlate the experimental data of each physical property as a function of both concentration and temperature. A quantitative analysis of variation was carried out for estimating the significance of the physical property’s data.     

Analysis of Variance (ANOVA) for Optimizing the Nano-SiO2 Content of High Performance Epoxy Nanocomposites

Epoxy based nanocomposite samples containing SiO₂ nanoparticles (0.0–3.0 %w) were prepared for physical and mechanical evaluation. Some thermomechanical and physical properties of samples were investigated using dynamic mechanical analysis (DMA), tensile strength, hardness and abrasion tests. The main aim of experimentation was to realize the optimum amount of nano-SiO₂ which would demonstrate the best improving effect on mechanical and physical properties of nanocomposite samples and finding how significant a factor is for improving in physical and mechanical properties. Analysis of variance (ANOVA) was applied for optimization of SiO₂ content in epoxy based nanocomposites.     

聚芳醚酮高温长时间下的断裂行为──2．物理老化的影响

研究了聚芳醚酮在２００℃下长时间放置过程中的密度，热焓，屈服及应力松弛行为随时间的变化规律．结果表明，随放置时间的增长，材料的结构形态与物性随时间的变化速率在１０小时后急剧减慢．文中对物性变化的时间依赖性进行了讨论．在应力松弛过程中出现银纹的现象可归结为物理老化过程中分子链间排列逐渐紧密的结果．     

Synthesis,Electronic Properties and WOLED Devices of Planar Phosphorus‐Containing Polycyclic Aromatic Hydrocarbons

We describe the synthesis and the physical properties of polyaromatic hydrocarbons (PAHs) containing a phosphorus atom at the edge. In particular, the impact of the successive addition of aromatic rings on the electronic properties was investigated by experimental (UV/Vis absorption, fluorescence, cyclic voltammetry) and theoretical studies (DFT). The physical properties recorded in solution and in the solid state showed that the P‐containing PAHs exhibit properties expected for an emitter in white organic light‐emitting diodes (WOLEDs).     

超支化树脂改性UV固化粉末涂料

本文将超支化树脂(HBP)与UV固化粉末涂料相结合,研究了超支化树脂对该涂料的树脂体系玻璃化温度、流变性能及涂膜各项物理性能的影响.结果表明:添加改性与未改性超支化树脂都能降低树脂体系的玻璃化温度,改性超支化树脂不影响体系的流变性能及涂膜性能,未改性超支化树脂可以降低体系粘度但使涂膜性能变差.     

Rice husk silica as a sustainable filler in the tire industry

In this paper, we studied commercially available precipitated rice husk silica (RHS) with conventional precipitated silica, which has nearly the same surface area, and replaced part of the carbon black with RHS and conventional silica in a basic tread formulation. All formulations were mixed with the same amount of filler during the study. Silica was used at 15, 30 and 50 phr loading, and part of the carbon black was replaced by silica. Compound curing characteristics, physical properties, rebound resilience, heat generation, abrasion loss, dynamic properties and morphology were analyzed. The results indicated that RHS demonstrated compound properties comparable to those of conventional silica. As part of the carbon black was replaced with conventional silica, a slower cure rate, higher rebound resilience, lower heat generation, lower abrasion loss, and lower tan delta were observed with no significant change in physical properties, but some changes in physical properties were observed using one way ANOVA analysis. We found the same trend when replacing part of the carbon black with RHS, such as a slower cure rate, higher rebound resilience, lower heat generation, lower abrasion loss, and lower tan delta with no significant change in physical properties, but some changes in physical properties were observed using one way ANOVA. This sustainable material could be used to replace conventional silica in tire compounding, as well as to replace a portion of carbon black with RHS for improved heat build-up, rolling resistance, and abrasion loss.     

Properties of Some Wool Keratin Copolymers

The properties of keratin following the formation of polymers in situ have been studied. It is important to determine any effects of the initiatory system on keratin in order to assess the role of the added polymer, The water content of the copolymer usually differs from that of the keratin and polymer measured as separate entities and influences the observed physical properties. Deposition of polymer has little direct effect on properties unless reaction with the keratin structure occurs. Observed physical properties suggest that polymer is predominately formed in the matrix component.