采用高分子自组装ZnO纳米线及其形成机理

介绍了一种能在各种晶面的硅衬底上制备垂直于衬底取向生长的ZnO纳米线阵列的新方法. 该法采用高分子络合和低温氧化烧结反应, 以聚乙烯醇(PVA)高分子材料作为自组装络合载体来控制晶体成核和生长. 首先通过PVA侧链上均匀分布的极性基团羟基(—OH)与锌盐溶液中的Zn²⁺离子发生络合作用, 然后滴加氨水调节络合溶液pH值为8.5±0.1, 使络离子Zn²⁺转变为Zn(OH)₂, 再将硅片浸入此溶液中, 从而在硅衬底表面得到较均匀的Zn(OH)₂纳米点, 随后在125 ℃左右Zn(OH)₂纳米点通过热分解转化为ZnO纳米点, 其后在420 ℃烧结过程中衬底上的ZnO纳米点在PVA高分子网络骨架对其直径的限域下逐渐取向生长成ZnO纳米线, 并且烧结初期PVA碳化形成的碳通过碳热还原ZnO为Zn, 再在氧气氛中氧化为ZnO的方式在纳米线顶端形成了催化活性点, 促进了纳米线顶端ZnO的吸收. 烧结后碳逐渐氧化被完全去除. 采用场发射扫描电镜(FE-SEM)、透射电镜(TEM, HR-TEM)和X射线衍射(XRD)对纳米线的分析结果表明, ZnO纳米线在硅衬底上分布均匀, 具有六方纤锌矿结构, 并且大多沿[0001]方向择优取向生长, 直径为20～80 nm, 长度可从0.5至几微米. 提出了聚合物控制ZnO结晶和形貌的网络骨架限域模型以解释纳米线的生长行为.     

氧化锌纳米线自组装定向生长动力学研究

研究了以极性高分子(如聚丙烯酰胺)长分子链作为自组装网络, 利用高分子软模板控制ZnO纳米点成核和ZnO纳米线定向生长, 从而使ZnO纳米线在半导体硅衬底上自组装生长的过程; 采用差示扫描量热法(DSC)测试了高分子络合-烧结法制备ZnO纳米线的结晶曲线, 对其结晶动力学进行了研究, 推导出结晶动力学方程为: 1－X_t＝exp(－7.475×10^－2t^1.9); 并利用热重(TG)测试结果, 通过热分解反应, 导出了反应动力学方程: dα/dT＝(3.76×10²³/Φ)e^－21340.8/T(1－α) ^2.8, 从而得到了化学反应速度随时间、浓度和温度变化的关系, 并用结果解释了实验现象.     

取向纳米ZnO/Cu_2O异质结阵列的制备及光电特性

以水热合成法制备的一维取向n型ZnO纳米线阵列为衬底,采用电化学沉积法在其上沉积生长一层p型Cu2O半导体包覆层,制备出了新型ZnO/Cu2O异质结纳米线阵列光敏器件.利用XRD、SEM、TEM、XPS、PL及光响应特性等测试方法对样品的形貌、晶体结构、化学成分及光电特性进行了分析表征.研究了生长条件对ZnO/Cu2O异质结纳米线阵列各种特性的影响.研究发现,适宜的沉积电压和沉积时间是保证ZnO/Cu2O异质结光敏器件具有适宜厚度核壳包覆层及较好光响应特性的关键因素.研究结果为ZnO及Cu2O半导体材料在光敏器件中的应用提供了实验基础.     

含胺烷基侧链的共轭磷光聚芴的合成、表征及其光电性能研究

通过Suzuki聚合反应合成了一种新型的含磷光单元的主链型聚芴类聚合物, 对其进行了表征分析, 并且研究了其在薄膜状态下的光学性质. 在以这种聚合物作为电致发光器件的发光层时, 用高功函数金属铝(Al)作为器件阴极时可以获得和用低功函数金属钡(Ba)作为阴极时相当的器件性能.     

聚乙烯基咔唑-花生酸有序复合膜的光电性质研究

用LB技术在石英和硅衬底上制备了聚乙烯基咔唑(PVK)的固态有序薄膜.荧光光谱研究表明,PVK在膜中的光致发光主要呈现激基缔合物的发射,其中心波长为418nm;表面光电压谱的测试揭示了PVK聚合物膜/p-Si体系具有显著的表面光伏效应.     

柔性硅纳米线阵列的制备及光催化性能研究

硅纳米线阵列是利用太阳能解决能源和环境问题的重要材料,然而,可用于柔性器件和生物相容性器件的柔性硅纳米线阵列的制备方法非常有限。本文通过化学气相沉积,以及高分子转移的方法,成功制备了具有不同高分子层厚度的柔性硅纳米线阵列,并研究了高分子层厚度对柔性硅纳米线阵列光催化性能的影响。结果表明,高分子层厚度越小,柔性硅纳米线阵列的光催化性能越强。因此,利用本文提出的制备方法得到的高分子层厚度低至5 μm的柔性硅纳米线阵列,具有作为高效柔性太阳能电池和全光解水系统光电极的潜力。同时,该研究结果也为设计具有高效光能转换能力的柔性纳米线阵列提供了重要依据。     

主链为咔唑-吖啶给体/侧基为三联吡啶受体的热诱导延迟荧光共轭聚合物合成及发光性质

成膜性能优异的聚合物发光材料适宜于可溶液加工大尺寸显示及照明器件制作,赋予其热诱导延迟荧光(TADF)特征能够有效改善器件发光性能.本工作以苯环对位桥连三联吡啶的吖啶衍生物(ABTPy)为TADF单体、咔唑(Cz)衍生物为共聚单体,利用交叉偶联反应,控制TADF单体摩尔投料比为1%、5%、10%和50%,合成了4个主链为咔唑-吖啶给体/侧基为三联吡啶受体的共轭聚合物PCzABTPy1～PCzABTPy50.低含量TADF单元聚合物溶液的光致发光光谱显示了低聚咔唑片段和TADF单元的双峰发射,发光峰位是420和488 nm,聚合物薄膜仅出现单峰发射,发光峰由470 nm红移至508 nm.聚合物瞬态荧光衰减光谱均包含纳秒级瞬时荧光(12～15 ns)和微秒级延迟荧光(1.3～4.8μs),证实聚合物具有TADF特性.以聚合物为发光层的非掺杂溶液加工电致发光器件实现了蓝光发射,发光波长位于452～484 nm.其中,PCzABTPy10发光器件展示了最优的发光性能,最大外量子效率(EQE)为9.4%,启亮电压为3.0 eV.在亮度1000 cd/m²时,器件EQE仍保...     

稀土铽配合物有机电致发光

利用三价稀土铽配合物作为发射层、二胺衍生物(TPD)以及聚乙烯咔唑(PVK)作为空穴传输层制备了有机电致发光器件. 器件的结构为 玻璃衬底/ITO/PVK 或者TPD/Tb3+ 配合物/Al, 其中空穴传输层TPD 和发光层Tb3+-配合物采用热蒸发办法成膜. 而空穴传输层PVK采用旋甩涂敷的方法成膜. 对于以上的两种器件均获得了来自Tb3+ 的窄峰发射, 在直流电压15.4 V驱动下, 器件发光亮度达210 cd·m-2.     

含有手性和发光官能团侧基的聚1-苯基-1-辛炔的合成与性能研究

设计并合成了一系列含手性和发光生色团侧基的聚（1-苯基-1-辛炔）衍生物{-[（C6H13）C=C（C6H4-p-CO2-R）]n-,R=[（1S）-endo]-（-）-冰片基（P3）,（1R,2S,5R）-（-）-薄荷基（P4）,-C6H4-p-（1R,2S,5R）-（-）-薄荷基（P5）,2-萘基（P6）,4-联苯基（P7）}.用WCl6-Ph4Sn作催化剂,成功地制备了这些具有中等产率和高分子量（Mw高达64000）的聚合物.聚合物的结构和性能通过NMR,TGA,UV,CD,PL和EL等分析方法进行了表征.所有聚合物都表现出良好的热稳定性,在N2保护条件下,其失重5%的温度在300～416℃之间.所有聚合物的带隙约为3.0eV.聚合物P4和P5表现出与聚合物链段螺旋性相对应的CD吸收.在UV辐照下,P3～P7的THF溶液均发射强烈蓝光,其最大发射波长位于485nm左右,量子效率均高于20%.聚合物薄膜发射与其溶液发射在相同的光谱区域,并表现出轻微的聚集诱导猝灭.制备了ITO/聚合物：PVK/BCP/Alq3/LiF/Al多层聚合物EL器件,其最大发射波长为487nm.随着侧基的改变,器件的最大亮度和外量子效率也随之发生变化,其中P6表现出最高的外量子效率（0.16%）.EL器件均具有良好的光谱稳定性,其EL最大发射峰几乎不随外加电压的变化而改变.     

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.     

Polymer-controlled crystallization of zinc oxide hexagonal nanorings and disks

In this study, we have developed a novel route to the synthesis of ZnO nanorings, disks, and diskoidlike crystals on a large scale by a facile solution-based method by using polymers as crystal growth modifiers. The crystals precipitated with polyacrylamide (PAM) as the additive show ringlike morphology. A possible growth mechanism of the ZnO nanostructures based on typical polymer-crystals interactions in a mild aqueous solution is given. The polymer contains in the side chain a large number of amide ligands that are able to coordinate with Zn(2+) ions, that is, the otherwise just weakly exposed (001) face, leading to a lowering of surface energy and inhibition of growth along this direction and the formation of ringlike morphologies. While in the presence of carboxyl-functionalized polyacrylamide (PAM-COOH), nearly monodispersed disklike crystals were observed and finally evolved into diskoidlike microstructures with the reaction time prolonged. Polymer-directed crystal growth and mediated self-assembly of nanocrystals may provide promising routes to rational synthesis of various ordered inorganic and inorganic-organic hybrid materials with complex form and structural specialization.     

Study on luminescence characteristic of the ZnO/polymer hybrid films

The cyclohexane solution of PS (polystyrene) and the ethyl acetate solution of PMMA (polymethyl methacrylate) were used as flowing liquid; the ZnO/polymer hybrid colloids were successively produced by focused pulsed laser ablation of ZnO target in interface of solid and flowing liquid. As solvent in the hybrid colloids has volatized, the ZnO/polymer hybrid films were obtained. The hybrid colloids were characterized by high-resolution transmission electron microscopy (HRTEM) and select-area electron diffraction (SEAD). The results show a good dispersion of the ZnO nanoparticles in the polymer matrix. The hybrid films were characterized by fluorescence spectrum, Fourier transform infrared spectroscopy (FTIR) spectroscopy, thermogravimetry with FTIR (TG/FTIR), and X-ray photoelectron spectrum. The results show the ZnO/polymer hybrid films can radiate strong blue light under ultraviolet. Meanwhile, the ZnO/polymer hybrid films have higher chemical stability than ZnO nanoparticles because nano-ZnO nanoparticles were enwrapped by polymers. In addition, the ZnO hybrid films have higher thermal stability then the related pure polymers because of strong interaction among ZnO nanoparticles and polymers.     

AN EXPERIMENTAL STUDY ON THE SOL/GEL PHASE TRANSITION OF LINEAR POLYMER IN THE PRESENCE OF CROSSLINKERS

The sol/gel phase diagrams were studied for two systems: polyacrylamide/Cr (III) andpolyacrylamide/glyoxal. Sol or gel phase could be distinguished according to the concen-trations of polymer and crosslinker. The boundary polymer concentration did not de-pend on the types of gelation and decreased with increasing polymer dimension (molecularweight and conformation). The gelation, which is basically interchain bonding, requires theoccurrence of entanglement. The overlap concentration is thus considered as the minimumpolymer concentration required for gelation.     

新型阳离子聚丙烯酰胺离解行为的研究

前文曾报导,以聚丙烯酰胺为母体,通过甲醛为桥梁引入二氰二胺可合成一种新型阳离子聚电解质,简称PAm·MG,它是一种弱聚碱的盐酸盐,结构式如下(S 为取代度):PAm·MG 对含活性艳红染料的废水有明显的絮凝脱色作用,其絮凝效果受聚合物的取代度、介质的pH 以及外加盐浓度的影响,而这些影响因素又直接与聚碱的离解行为或胺基离子化度(指已离子化的胺基占全部胺基的分数)密切相关.为此,本文对影响PAm·MG 离解行为和离子化度的一些因素作进一步探讨,并通过粘度测定考察离解行为对聚合物在水中形态的影响,为PAm·MG 的实际应用提供理论根据.     

ZnO纳米线基MWNTs/PVDF复合热电材料的制备及特性研究

将不同比例的多壁碳管(MWNTs)与聚偏二氟乙烯(PVDF)聚合物混合后,喷涂于n型ZnO半导体纳米线阵列上,制备了一种新型ZnO纳米线基MWNTs/PVDF热电复合材料.与以往采用价格昂贵的p型与n型单壁碳纳米管(SWNTs)与聚合物混合制备的复合热电材料特性相比,这种新型热电复合材料在降低制造成本的同时,利用分散于聚合物中MWNTs的一维电子传输特性及形成的大量界面势垒,加上ZnO半导体纳米线具有的较高载流子密度与迁移率,提高了复合热电材料中电子的输运特性,增加了材料对声子的散射强度.测试发现,在一定的温度梯度下,随着MWNTs添加质量百分比的增加,热电材料的温差电动势和电导率也随之增加,但其Seebeck系数变化量不大.研究表明,这种热电材料有望替代采用p型与n型SWNTs构建的SWNTs/PVDF复合热电材料.研究结果对开发超轻、无毒、廉价、可应用于各种微纳电子领域的新型电源具有重要的参考价值.     

Biomineralization‐Inspired Preparation of Zinc Hydroxide Carbonate/Polymer Hybrids and Their Conversion into Zinc Oxide Thin‐Film Photocatalysts

The development of ZnO thin films has been achieved through the conversion of zinc hydroxide carbonate thin‐film crystals. Crystallization of this compound is induced by a biomineralization‐inspired method with polymer‐stabilized amorphous precursors. The crystals grow radially on polymer matrices, leading to the formation of zinc hydroxide carbonate/polymer thin‐film hybrids that fully cover the substrate. These hybrids are converted into ZnO and retain their thin‐film morphologies. The resultant ZnO thin films exhibit a preferential crystallographic orientation that is attributed to the alignment of zinc hydroxide carbonate crystals before conversion. In addition, a photocatalytic function of the ZnO thin films has been demonstrated by analyzing the oxidation reaction of 2‐propanol. The biomineralization‐inspired approach reported herein is a promising way to develop ZnO materials with controlled morphologies and structures for photocatalytic applications.     

Preparation of styrene polymer/ZnO nanocomposite latex via miniemulsion polymerization and its antibacterial property

Styrene polymer/ZnO nanocomposite latex was fabricated using miniemulsion polymerization in the presence of coupling agent 3-aminopropyltriethoxysilane (APTES) and hexadecane as hydrophobe. The size distribution and morphology of the composite latex particles were characterized by dynamic light scattering and transmission electron micrograph. X-ray photoelectron spectroscopy and Fourier transform infrared spectrophotometer results demonstrate that ZnO nanoparticles were encapsulated into polymer phases. The coupling treatment of ZnO with APTES can improve the dynamic contact angles of ZnO nanoparticle with water to enhance its hydrophobicity. When 0.6% APTES to ZnO (wt/wt) is used to modify ZnO, the encapsulation efficiency of ZnO reaches to 95%. It shows that the high encapsulation efficiency improves dispersion of ZnO nanoparticles in polymer film by scanning electron microscope. The stable structural hybrid latex can adequately exert unique function of nanoparticles in coatings. It indicates that the coatings added the composite latex exhibits perfect antibacterial activity, which has a tremendous potentiality in the field of coating materials.     

Hybrid polymer/zinc oxide photovoltaic devices with vertically oriented ZnO nanorods and an amphiphilic molecular interface layer

We report on the effect of nanoparticle morphology and interfacial modification on the performance of hybrid polymer/zinc oxide photovoltaic devices. We compare structures consisting of poly-3-hexylthiophene (P3HT) polymer in contact with three different types of ZnO layer: a flat ZnO backing layer alone; vertically aligned ZnO nanorods on a ZnO backing layer; and ZnO nanoparticles on a ZnO backing layer. We use scanning electron microscopy, steady state and transient absorption spectroscopies, and photovoltaic device measurements to study the morphology, charge separation, recombination behavior and device performance of the three types of structures. We find that charge recombination in the structures containing vertically aligned ZnO nanorods is remarkably slow, with a half-life of several milliseconds, over 2 orders of magnitude slower than that for randomly oriented ZnO nanoparticles. A photovoltaic device based on the nanorod structure that has been treated with an amphiphilic dye before deposition of the P3HT polymer yields a power conversion efficiency over four times greater than that for a similar device based on the nanoparticle structure. The best ZnO nanorod:P3HT device yields a short circuit current density of 2 mAcm(-2) under AM1.5 illumination (100 mW cm(-2)) and a peak external quantum efficiency over 14%, resulting in a power conversion efficiency of 0.20%.     

ZnO在NaY沸石表面的分散研究

利用ＸＲＤ、Ｒａｍａｎ光谱分析了影响ＺｎＯ在ＮａＹ表面分散的各种因素，发现延长干燥时间和多次浸渍能促进ＺｎＯ的分散，测量ＺｎＯ的最大分散量为０．４６ｇ／ｇＮａＹ，已远大于文献结果。与模型估算值进行了比较分析，探讨了ＺｎＯ在分子筛内表面的排布状态。     

Fabrication of zinc oxide/poly(styrene) grafted nanocomposite latex and its dispersion

Zinc oxide nanoparticles, with an average size of about 40 nm, were encapsulated by polystyrene using in situ emulsion polymerization in the presence of 3-methacryloxypropyltrimethoxysilane (MPTMS) as a coupling agent and polyoxyethylene nonylphenyl ether (OP-10) as a surfactant. Polymerization mechanism of nanocomposite latex was discussed. Transmission electron microscopy (TEM) proved the presence of ZnO nanoparticle appeared to be monodisperse in nanosize in polymer composite particles. ZnO/PS nanocomposites were characterized by Fourier transform infrared spectra (FT-IR), X-ray photoelectron spectroscopy (XPS), thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results of FT-IR and XPS revealed that the surface of ZnO particle was successfully grafted by PS through the link of the coupling agent between ZnO and polymer. TGA and DSC results indicated an enhancement of thermal stability of composite materials compared with the pure polymer. SEM (scanning electron microscope) images showed a perfect dispersion of the ZnO particles in latex film. In addition, UV-visible absorption measurements demonstrated that the ZnO/PS composite coatings display a perfect performance of absorbing UV light.