聚(N-苯基马来酰亚胺)-b-聚(4-乙烯基吡啶)-CdS纳米复合物的光学性质

用可逆加成锻炼链转移(RAFT)聚合方法合成了两亲性聚(N-苯基马来酰亚胺)-b-聚(4-乙烯基吡啶)-Cd2(PNPV-Cd2)高分子配合物.Cd2离子与4VP基团配位并与硫代乙酰胺分解产生的S2-离子原位生成CdS纳米粒子.聚(N-苯基马来酰亚胺)-b-聚(4-乙烯基吡啶)- CdS( PNPVCdS)中CdS的含...     

耐热级ABS树脂的研制

研究了不同耐热剂对ABS耐热性作用效果的差异,实验表明：N-苯基马来酰亚胺（NPMI）耐热改性剂共聚物（NPISA）对提高ABS耐热性效率较高。当采用ABS粉30份,N-苯基马来酰亚胺（NPMI）耐热改性剂共聚物（NPISA）10-50份,SAN粉20～60份,能得到热变形温度在95℃～105℃之间的不同等级的耐热ABS树脂材料。     

N-(苯并环丁烯-4-基)马来酰亚胺的制备及热稳定性

对N-(苯并环丁烯-4-基)马来酰亚胺原有文献的合成方法进行了改进,在温和条件下使该单体产率有所提高。研究了该单体分别与苯乙烯和N-苯基马来酰亚胺在溶液中的二元共聚反应,对所得的共聚物进行表征,并对其热性能进行了分析。结果表明,N-(苯并环丁烯-4-基)马来酰亚胺的均聚物具有很高的热分解温度,初始分解温度为400℃,480℃的热失重仅为10%,将其与苯乙烯共聚可显著提高苯乙烯的耐热性,有望用于高性能复合材料的树脂基体。     

含氰基的N-取代苯基马来酰亚胺的合成及性能

合成了N-[4-(4-邻苯二甲腈基)苯氧基]马来酰亚胺(1)和N-[4-(3-邻苯二甲腈基)苯氧基]马来酰亚胺(2)两种含氰基的N-取代苯基马来酰亚胺化合物。用FT-IR,1H-NMR和EA对其结构进行了确认。利用DSC和TGA等手段,初步研究了1和2的热行为。DSC研究结果显示:1和2发生马来酰亚胺双键的热自由基聚合反应峰比传统化合物二苯甲烷双马来酰亚胺(BMI)高;TGA研究结果表明,在氮气氛下305℃前,1和2热失重,800℃的残炭率高于BMI,分别达到了50%和57%,证明分子结构中引入腈基可有效降低马来酰亚胺在高温下的热分解引起的热失重,提高材料的耐热性能。     

基于RAFT过程的N-(4-羧基苯基)马来酰亚胺和苯乙烯可控自由基共聚合

采用N-(4-羧基苯基)马来酰亚胺为单体,四氢呋喃做溶剂,偶氮二异丁腈为引发剂,以RAFT试剂二硫代苯甲酸苄酯为链转移剂,成功地进行了N-(4-羧基苯基)马来酰亚胺和苯乙烯的共聚合反应。结果表明,得到的聚合物数均分子量随单体转化率增加而呈线性增加,且聚合物的分子量分布小于1.5,二硫代苯甲酸苄酯显示出对聚合反应的良好控制作用。通过不同反应温度的聚合反应动力学得到共聚合反应的表观活化能为1.39 kJ/mol。     

二亚胺镍配合物催化乙烯/4-乙烯基吡啶的共聚合

以N,N-二(2,6-二异丙基苯基)苊二亚胺氯化镍(NiLCl2)为主催化剂,AlEt2Cl为助催化剂,催化乙烯与4-乙烯基吡啶(4-VP)共聚合。研究结果表明,在一定条件下,该催化体系可以催化乙烯与4-乙烯基吡啶共聚合。极性单体的浓度对共聚合反应活性、共聚物的组成等有很大的影响,随着4-乙烯基吡啶浓度的增加,参与共聚的乙烯迅速减少,4-乙烯基吡啶均聚增加。最佳反应条件是单体浓度为0.46mol/L、n(Al)/n(Ni)为600、温度为30℃,这时共聚合催化活性达到19.7 kg/mol Ni.h,共聚物中4-乙烯基吡啶的摩尔百分数可达4.2%。     

基于羟基苯基马来酰亚胺的双马树脂共混物的制备和热性能

近来文献报道了基于羟基苯基马来酰亚胺的双弓树脂，这些材料是以4-（N-马来酰亚胺苯基）缩水甘油醚（MPGE）和各种二元酚和硅烷醇反志制谢的。这种方法将导致双马树脂具有在有机溶剂中稿解性好、熔点低和加工窗口宽的优点。固化后聚合物的玻璃化温度高于210℃，在350℃以内具有良好的热稳定性。MPGE还可以用于与氨基化合物反应，形成玻璃化温度200℃左稻的交联产物．     

新型聚合物NSMA的热性能及热降解动力学

采用差示扫描量热仪和红外光谱仪研究了N-苯基马来酰亚胺、苯乙烯和马来酸酐三元共聚物(NSMA)的热性能,热降解过程和热降解动力学.结果表明,N-苯基马来酰亚胺可以有效地提高聚合物的热性能,合成的NSMA的玻璃化温度(Tg)达212℃;用Flynn-Wall-Ozawa法求得的NSMA热降解表观活化能为186.31kJ/mol,由Crane法求得热降解的反应级数n=1.0.     

N-苯基马来酰亚胺-马来酸酐的合成及对尼龙6耐热性能的影响

利用溶液聚合法合成了一种耐热改性剂N-苯基马来酰亚胺-马来酸酐二元共聚物(NMA)。采用红外光谱对其结构进行表征,并通过熔融共混法制备了尼龙6/N-苯基马来酰亚胺-马来酸酐共混物(PA6/NMA),且通过扫描电镜、差示扫描量热分析、热重分析、热变形试验机及旋转流变仪对共混物耐热性能进行研究。红外光谱分析证实NMA中N-苯基马来酰亚胺(N-PMI)含量随N-PMI投料量的增加而增加;差示扫描量热分析和热重分析表明经NMA改性后的PA6的熔融温度与结晶度下降,热稳定性大幅提高;随着NMA中N-PMI含量降低,共混物热变形温度及力学性能先降低后升高;扫描电镜与旋转流变测试均表明PA6与NMA两相间的粘合作用随N-PMI含量的降低而增大。     

可使环氧树脂的韧性倍增的新型添加剂

日本横浜国立大学工程部物质工程科的研究人员开发出可使环氧树脂的韧性提高一倍,耐热温度也提高10℃的新型添加剂。新添加剂是N-苯基马来酰亚胺苯乙烯共聚物,因结构中含有乙烯基,故与工程塑料的结构极相似。将     

CdSe胶质量子点的电致发光特性研究

采用胶体化学法合成硒化镉(CdSe)胶质量子点, 在此基础上制成了以CdSe胶质量子点为有源层, 结构为ITO/ZnS/CdSe/ZnS/Al的电致发光(EL)器件. 透射电镜测量表明量子点的尺寸为4.3 nm, 扫描电子显微镜测量ZnS薄膜和Al薄膜结果显示表面均较为平整, 由器件结构的X射线衍射分析观察到了CdSe(111)、ZnS(111)等晶面的衍射, 表明器件中包含了CdSe量子点和ZnS绝缘层材料. 光致发光谱表征胶质量子点的室温发光峰位于614 nm, 电致发光测量得到器件在室温下的发光波长位于450 ~ 850 nm, 峰值在800 nm附近. 本文对电致发光机制及其与光致发光谱的区别进行了讨论.     

含非共轭双键RAFT试剂的合成及与乙酸乙烯酯的共聚

以烯丙基胺、溴丙酰溴及黄原酸钾为原料,制备出含非共轭双键可逆加成-断裂链转移聚合(RAFT)试剂——N-烯丙基-(2-乙基黄原酸基)丙酰胺(NAPA)。研究了加料顺序、反应温度、溶剂等对NAPA产率的影响,获得了较优的合成条件,最终产率可达70%;红外光谱、核磁共振氢谱表明其化学结构与设计结构相符。以NAPA与乙酸乙烯酯(VAc)共聚,制备出具有支化结构的聚乙酸乙烯酯。采用称量法、核磁共振氢谱和凝胶渗透色谱法等手段研究了NAPA与VAc的共聚行为及共聚产物的结构,结果表明,NAPA与VAc共聚过程符合"活性"/可控自由基聚合特征;同时,在引发剂偶氮二异丁腈(AIBN)比例恒定的情况下,支化PVAc聚合物分子链上NAPA含量随着投料比NAPA/VAc的增加而增加。     

Photoluminescence enhancement of synthesized ZnS-based-nanocrystals and aging effect on its emitting color

Various colors-emitting ZnS:Cu,Cl, ZnS:Cu,Cl,Mn and ZnS:Mn nanocrystals (NCs) which were shown to be about 3 nm sized-particle were synthesized by using a solution chemistry. And the luminescences of the synthesized ZnS-based NCs were investigated through photoluminescence excitation (PLE) and photoluminescence (PL) spectroscopy. The PLE and PL intensities of the ZnS-based NCs depends on their reflux time, and red shifted maximum PLE wavelengths of the synthesized NCs showed with increasing reflux time. The increased maximum PL intensity of NCs with increasing reflux time is due to the enhanced crystallinity of the NCs. And the shifted emitting colors of the NCs showed after aging treatment compared to those of refluxed NCs. The amount of shifted wavelength of Cu,CI doped ZnS, Cu,CI and Mn co-doped ZnS, only Mn doped ZnS NCs were -22 nm, +18 nm, and +14 nm, respectively.     

Synergistic effects of SPR and FRET on the photoluminescence of ZnO nanorod heterostructures

Solution-grown ZnO nanorods (NRs) were successfully conjugated with CdSe/ZnS quantum dots (QDs) and Ag nanoparticles (NPs) to suppress intrinsic defect emission and to enhance band-edge emission at the same time. First, high-density and high-crystallinity ZnO NRs of diameter 80–90 nm and length 1.2–1.5 μm were grown on glass substrates using a low-temperature seed-assisted solution method. The as-synthesized ZnO NRs showed sharp photoluminescence (PL) band-edge emission centered at ～377 nm together with broad defect emission in the range of ～450–800 nm. The ZnO NRs were decorated with CdSe/ZnS QDs and Ag NPs, respectively, by sequential drop-coating. The PL of CdSe/ZnS QD||ZnO NR conjugates showed that ZnO band-edge emission decreased by 73.8% due to fluorescence resonance energy transfer (FRET) and charge separation between ZnO and CdSe/ZnS by type II energy band structure formation. On the other hand, Ag NP||CdSe/ZnS QD||ZnO NR conjugates showed increased band-edge emission (by 25.8%) and suppressed defect emission compared to bare ZnO NRs. A possible energy transfer mechanism to explain the improved PL properties of ZnO NRs was proposed based upon the combined effects of FRET and surface plasmon resonance (SPR).     

水溶性ZnS量子点的共沉淀法制备、 表征及其光学性能

以硫化钠和乙酸锌为反应物,3-巯基丙酸为表面包覆剂,利用共沉淀法制备了水溶性ZnS量子点。并采用X射线衍射仪、透射电子显微镜和荧光分光光度计等对样品的结构、形貌、粒径和光学性能进行了表征。结果表明:所得样品为ZnS立方型闪锌矿结构,量子点的形状呈不规则球形,粒径主要集中在4.8nm左右;样品在585～590nm之间出现了黄色荧光发射波峰。同时,利用红外光谱对ZnS量子点的合成机理进行了初步分析。     

掺锶量对羟基磷灰石形貌及其荧光特性的影响

采用水热合成法制备了一系列具有不同微观形貌和荧光性能的掺锶羟基磷灰石粉末。通过X射线衍射、红外光谱、电子能谱、扫描电镜和荧光光谱表征样品的物相、形貌及荧光性能。结果表明: 所制备的样品形貌为1~ 3 μm的由微小晶粒聚集而成的球形颗粒, 但随着掺锶量的变化, 组成球形颗粒的微小晶粒形貌会出现较大的差异。 未掺锶羟基磷灰石晶粒形貌为短棒状, 随着掺锶量的增加, 微小晶粒逐渐变为片状而后转变为长棒状。样品能在紫外光(波长351 nm)激发下发出明亮的蓝色荧光(波长375~500 nm, 最强峰位432 nm), 且荧光强度随掺锶量增加先增强, 而后减弱, 在掺锶量为30mol%时达到最大。     

低温水热法制备ZnS:Co+Cr纳米晶及其光学性能研究

采用低温水热法制备出3-巯基丙酸(MPA)修饰的ZnS:Co+Cr纳米晶. 利用X射线衍射仪、粒度分析仪、透射电镜、紫外-可见分光光度计、荧光分光光度计和XPS能谱仪等对ZnS:Co+Cr纳米晶的结构、形貌、粒径分布和发光性能进行了表征. 结果表明: 合成的ZnS:Co+Cr纳米晶有较好的单分散性, 平均粒径为9.3 nm, 均为立方闪锌矿结构; ZnS:Co+Cr纳米晶的吸收边位于320 nm处, 并在728 nm处出现Co²⁺的特征吸收峰; 当Cr²⁺浓度为0.75at%, 水热反应温度为160℃时, ZnS:Co+Cr纳米晶PL峰最强; XPS能谱表明Cr²⁺部分被氧化成Cr³⁺。     

Facile synthesis and luminescence characteristics of high-quality CdS: Eu/ZnS core/shell nanocrystals with biocompatibility

In this paper, we report a facile method to synthesize high quality CdS: Eu nanocrystals (NCs) and CdS: Eu/ZnS NCs with strong photoluminescence (PL). The influence of various experimental variables including the concentration of Eu3+ ions, the reaction time and the reaction temperature were investigated systematically. In addition, the PL properties of CdS: Eu NCs exhibited pH sensitive. Under the acid condition, pH value of the CdS: Eu NCs solution played an important role in determining PL emission intensity. However, under the alkaline condition, the obtained CdS: Eu NCs exhibited a tunable PL emission wavelength (from 490 nm to 610 nm) when pH value was adjusted from pH 7 to 10. After coating with ZnS shell, the CdS: Eu/ZnS NCs showed enhanced PL intensity compare with one of the CdS: Eu NCs. The CdS: Eu NCs and CdS: Eu/ZnS NCs were characterized by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). In addition, the biocompatibility of these NCs was measured by hemolytic test, which indicated that CdS: Eu/ZnS NCs were more biocompatible than CdS: Eu NCs at the same conditions. It can be expected that CdS: Eu/ZnS NCs are promising biolabeling materials.     

Structural and optical properties of zinc sulphide-polyvinyl alcohol (ZnS-PVA) nanocomposite thin films: effect of Zn source concentration

ZnS-PVA nanocomposite thin films are grown by chemical bath deposition (CBD) method by varying the concentration of zinc source. Formation of nanocrystalline hexagonal ZnS is confirmed by X-ray diffraction. Hexagonal form is predominant at some lower concentration. The morphological properties of the films are determined by transmission electron microscope (TEM). The particle size as given by TEM indicates increase in particle size. Bandgap measured from UV-Visible transmission spectra shows a decreasing trend with decrease of Zn source concentration. Photoluminescence (PL) measurement showed blue emission centred at 417 nm and that the intensity decreases with decrease in Zn source concentration.