嵌段共聚物自组装薄膜中纳米结构的形成及应用

嵌段共聚物在固体基底上可通过多种技术形成薄膜,如铸膜、涂膜、浸渍膜及旋涂膜。借助于热退火、溶剂蒸气退火或者非溶剂引起的相分离,在这些薄膜中可形成有序纳米结构,如柱状结构、层状结构、双连续结构和多孔结构等。这些结构在下一代的光刻技术、光子晶体、与锂离子电池等相关的离子传输、分离和催化等领域都有重要的潜在应用。本文介绍了近年来这方面的研究进展,旨在为进一步的探讨提供参考。     

退火气氛对掺银TiO2薄膜结构和光催化性能的影响

本文采用sol-gel法制备了掺银的TiO2/glass纳米光催化薄膜,并分别在空气和真空条件下对薄膜进行退火处理, 结构和光催化性能的测试结果表明, 退火气氛对薄膜的结构和薄膜对染料溶液的光催化降解效率都有影响。经真空退火处理的TiO2及Ag-TiO2薄膜较空气中退火处理的同样薄膜的光催化性能都低, 但适量掺银的Ag-TiO2薄膜的光催化活性较TiO2有不同程度的增强。     

表面图案诱导两嵌段共聚物形成穿孔层状结构的模拟

利用耗散粒子动力学方法研究了两嵌段共聚物在表面圆形图案诱导下的相行为.通过调节圆形诱导图案的半径和嵌段共聚物薄膜的厚度,体系出现了非常丰富的穿孔层状相结构(PLS).经过区分将这些结构分为4类,并用PLS-Ⅰ,PLS-Ⅱ,PLS-Ⅲ,PLS-Ⅳ表示.绘制了这些结构与圆形图案半径和薄膜厚度关系的相图,并分析了这些结构出现的原因和规律,为设计和发展嵌段共聚物功能薄膜材料提供理论支持.     

退火温度对CdSe纳米薄膜的形成及光电性能影响

在室温下,采用循环伏安法在ITO上沉积CdSe纳米薄膜。利用X射线衍射仪(XRD)、场发射扫描电镜(FESEM)、原子力显微镜(AFM)、X射线光电子能谱分析(XPS)、紫外-可见(UV-VIS)分光光度计以及电化学工作站对不同温度退火后的CdSe纳米薄膜的晶体结构、形貌、光学性能、光电化学性能进行表征和测试。结果表明,退火温度对CdSe纳米薄膜的形貌和性能起到关键性作用。薄膜表面平整、厚度均匀,且由呈纳米颗粒状的立方相CdSe构成;经退火后,CdSe纳米颗粒出现不同程度的长大现象,Se含量随退火温度的升高而减少。紫外-可见吸收光谱表明随着退火温度的升高,CdSe纳米薄膜对可见光的吸收发生红移,表明禁带宽度逐渐减小,表现出量子尺寸效应。通过光电流测试表明随着退火温度的升高,CdSe薄膜的光电响应效应显著提高。     

退火温度对CdSe纳米薄膜的形成及光电性能影响

在室温下,采用循环伏安法在ITO上沉积CdSe纳米薄膜。利用X射线衍射仪(XRD)、场发射扫描电镜(FESEM)、原子力显微镜(AFM)、X射线光电子能谱分析(XPS)、紫外-可见(UV-VIS)分光光度计以及电化学工作站对不同温度退火后的CdSe纳米薄膜的晶体结构、形貌、光学性能、光电化学性能进行表征和测试。结果表明,退火温度对CdSe纳米薄膜的形貌和性能起到关键性作用。薄膜表面平整、厚度均匀,且由呈纳米颗粒状的立方相CdSe构成;经退火后,CdSe纳米颗粒出现不同程度的长大现象,Se含量随退火温度的升高而减少。紫外-可见吸收光谱表明随着退火温度的升高,CdSe纳米薄膜对可见光的吸收发生红移,表明禁带宽度逐渐减小,表现出量子尺寸效应。通过光电流测试表明随着退火温度的升高,CdSe薄膜的光电响应效应显著提高。     

丝网印刷法制备纳米银线透明导电薄膜

以高纯纳米银线作为导电介质,采用低成本丝网印刷法在普通透明玻璃基底上制备纳米银线薄膜层。经低温退火处理后,采用冷场发射扫描电子显微镜对薄膜的形貌进行表征;分别采用紫外可见分光光度计和四探针测试仪对薄膜的光学透过率和导电性能进行测试。实验系统研究了印刷浆料中纳米银线的含量、印刷层数和退火温度对薄膜的光学透过率和导电性能的影响。当印刷浆料中纳米银线的含量为3%(w/w),印刷层数达到3层,经低温275℃退火后,可制备出光电性能良好的纳米银线薄膜,该薄膜最大可见光透过率为39.4%,表面方块电阻仅为25.6Ω·□~(-1)。     

硫醇类配体修饰金纳米粒子在嵌段共聚物中自组装的研究进展

本文综述了不同类型硫醇配体修饰金纳米粒子的合成方法以及功能性金纳米粒子在嵌段共聚物薄膜中的自组装研究进展,重点介绍了硫醇类配体修饰金纳米粒子的合成方法,包括Brust合成法、原位合成法、grafting from合成法、配体置换法、单晶模板法等。总结了硫醇基小分子或聚合物配体修饰的金纳米粒子与嵌段共聚物之间自组装的调控方法,如利用配体与嵌段共聚物组分的隔离作用、配体与嵌段共聚物组分形成的氢键作用、溶剂蒸气退火或热退火等诱导嵌段共聚物/纳米粒子复合薄膜自组装。展望了功能性金纳米粒子以及嵌段共聚物/金纳米复合材料的发展方向。     

仿花瓣表面多功能高分子纳米薄膜的制备

以红玫瑰花瓣为模板, 用纳米压印图案转移法进行仿生合成, 获得具有多功能性的高分子薄膜. 通过将薄膜进行染色, 制得了具有特殊花瓣颜色的人工薄膜, 并探讨了化学色与结构色之间的关系.     

退火温度对TiO_2/CdSe纳米片异质结薄膜光电性能的影响

采用水热法在FTO上制备(001)高活性晶面主导的TiO_2纳米片薄膜,利用循环伏安法在TiO_2纳米片薄膜上沉积CdSe颗粒,制备了TiO_2/CdSe纳米片异质结薄膜。分别在150、250、350、450℃,氩气保护气氛中对样品进行退火。利用X射线衍射仪(XRD)、场发射扫描电镜(FESEM)、X射线光电子能谱分析仪(XPS)、紫外-可见(UV-Vis)分光光度计以及电化学工作站对不同温度退火后的TiO_2/CdSe纳米片异质结薄膜的微观形貌、晶体结构、光电化学性能进行表征和测试。结果表明:六方相CdSe纳米颗粒均匀包覆在TiO_2纳米片表面,直径30 nm左右;随着退火温度的升高CdSe纳米颗粒长大,形成光滑的CdSe薄膜,且晶化程度提高;TiO_2纳米片表面的Se元素与Cd元素发生氧化;TiO_2/CdSe纳米片异质结薄膜对可见光的吸收光谱发生红移,禁带宽度逐渐减小。光电化学性能测试表明随着退火温度的升高,TiO_2/CdSe纳米片异质结薄膜的光电流密度显著提高,开路电压减小,但由于SeO_2和CdO的出现,导致填充因子减小,影响光电转换效率的提高。在本实验条件下,TiO_2/CdSe纳米片异质结薄膜的最佳退火温度为150℃,填充因子为0.77,光电转换效率达到3.12%。     

丝网印刷法制备纳米银线透明导电薄膜

以高纯纳米银线作为导电介质,采用低成本丝网印刷法在普通透明玻璃基底上制备纳米银线薄膜层。经低温退火处理后,采用冷场发射扫描电子显微镜对薄膜的形貌进行表征;分别采用紫外可见分光光度计和四探针测试仪对薄膜的光学透过率和导电性能进行测试。实验系统研究了印刷浆料中纳米银线的含量、印刷层数和退火温度对薄膜的光学透过率和导电性能的影响。当印刷浆料中纳米银线的含量为3%(w/w),印刷层数达到3层,经低温275℃退火后,可制备出光电性能良好的纳米银线薄膜,该薄膜最大可见光透过率为39.4%,表面方块电阻仅为25.6Ω·□^-1。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.