Ta2O5空心球的制备及光催化性能

采用无皂乳液聚合法合成了粒径为500 nm的聚苯乙烯(PS)球。运用层层自组装技术在PS球表面交替沉积单分子层的TaO3纳米页与聚二烯丙基二甲基氯化铵(PDDA)多层膜,650℃煅烧除去PS模板和PDDA高分子层后,得到Ta2O5空心球。空心球的直径为500 nm左右,壁厚约10 nm。XRD结果显示该空心球为正交晶系Ta2O5。空心结构显著提高了Ta2O5的光催化活性,在紫外光照射60 min后,Ta2O5空心球降解亚甲基蓝达90%以上,而商品Ta2O5只能降解28%。     

静电自组装铁电超薄膜及其性能研究

利用静电自组装方法在石英玻璃表面交替沉积聚二烯丙基二甲基氯化铵(PDDA)和聚偏氟乙烯(PVDF)超薄膜,制得PDDA/PVDF铁电复合超薄膜.通过石英晶体微天平实时监测超薄膜的沉积,研究了超薄膜的表面形貌、结构及电性能.结果表明,自组装每层PVDF超薄膜的厚度为7.5 nm;PDDA/PVDF铁电复合超薄膜的表面平整、均匀,其中C1s的光电子能谱与极化处理后充负电荷的PVDF铁电聚合物一致,但F1s由于溶解再组装过程而降低了0.3 eV;静电自组装材料纳米级的薄膜厚度和聚合物的络合作用导致了铁电复合超薄膜的非晶结构和高的表面电阻率.     

聚电解质PSS/PDDA分子沉积膜动力学

聚苯乙烯磺酸钠;;聚二烯丙基二甲基胺盐酸盐;聚电解质PSS/PDDA分子沉积膜动力学     

等离激元纳米贴片天线耦合MEH-PPV超薄膜的高亮快速发射（英文）

作为一类潜在的纳米光源，共轭聚合物薄膜的荧光寿命通常在1～10 ns的范围内，这阻碍了其在高速光子器件中的应用。本文实现了等离激元纳米贴片天线(NPA)耦合聚[2-甲氧基-5-(2-乙基己氧基)-1,4-苯基乙烯基](MEH-PPV)薄膜的高亮、快速发射，其中11 nm厚的聚(二烯丙基二甲基氯化铵)/聚苯乙烯磺酸钠(PDDA/PSS)_n多层自组装膜用作介质层来调节等离激元微腔的损耗特性。实验结果表明，MEH-PPV超薄膜的发射强度增强了1.9倍，而辐射速率增加了7.2倍。以上结果为开发基于MEH-PPV聚合物薄膜的高速光子源提供了理论依据。     

聚电解质PDDA/PSS层层自组装膜的渗透汽化性能

采用聚电解质层层自组装(LbL)技术, 在不同盐浓度下制备了聚(二烯丙基二甲基氯化铵)/聚苯乙烯磺酸钠(PDDA/PSS) 多层自组装膜, 并用于渗透汽化性能的研究. 重点考察了组装溶液中NaCl的浓度、组装层数及操作温度对自组装膜的异丙醇脱水性能的影响. 同时, 用扫描电镜观测了不同条件下制备膜的表面形貌. 结果表明, 在高NaCl含量的聚电解质溶液中只需组装几个双层的LbL膜, 即能获得较高的分离因子和较大的通量, 并解释了该LbL膜呈现反“trade-off”现象的原因.     

胶体颗粒在聚电解质多层膜表面的可控组装

利用原子力显微镜和扫描电子显微镜研究了磺化聚苯乙烯胶体颗粒在由聚二甲基二烯丙基氯化铵和聚苯乙烯磺酸钠层状自组装而成的多层膜表面的组装.该组装受表面性质影响,通过对多层膜的最外层的组装条件或利用盐溶液对多层膜进行后处理可以控制胶体颗粒在膜表面的组装密度.     

预混合自组装辣根过氧化物酶生物活性膜及其催化活性研究

以阳离子化的辣根过氧化物酶 (HRP)和阴离子聚苯乙烯磺酸钠 (PSS)的预混合溶液 ,与阳离子聚电解质聚二甲基二烯丙基氯化铵 (PDDA)通过逐层组装 ,在阴离子化聚对苯二酸乙二酯 (PET)表面构建了多层生物活性膜 .用紫外 可见光谱仪 (UV Vis)和原子力显微镜 (AFM)研究了交替自组装膜的结构和表面形膜 ,并测定了自组装膜的生物催化活性 .结果表明 ,预混合溶液中的PSS与HRP一起沉积在PDDA膜层上组装成 (PSS+HRP)膜层 ,且每层中PSS和HRP的比例一致 ;(PSS +HRP)膜层呈条状分布 ,膜表面较为平整 ;多层膜中的HRP催化H2 O2 与 4 氨基安替比林的显色反应的表观米氏常数为 9 7× 10 - 5mol·L- 1 (相对于H2 O2 底物 ) ,较溶液中 (1 5 2× 10 - 4mol·L- 1 )的小 .     

静电层层自组装制备聚苯乙烯微球(核)/MCM-41纳米粒子(壳)阶层结构复合微粒

采用聚苯乙烯磺酸钠(PSS)和聚二烯丙基二甲基氯化铵(PDDA)两种聚电解质, 通过静电层层自组装成功地将MCM-41介孔二氧化硅纳米粒子包覆到聚苯乙烯(PS)微球表面. 实验结果表明, 当以尺寸为1.4 μm的PS微球为核时, 包覆了两个聚电解质双层(PDDA/PSS)2的PS(PDDA/PSS)2(PDDA/MCM-41)复合结构微粒与包覆了一个聚电解质双层(PDDA/PSS)的PS(PDDA/PSS)(PDDA/MCM-41)复合结构微粒相比, 复合结构微粒之间的交联程度降低, 但是MCM-41纳米粒子在聚苯乙烯微球表面的包覆都比较松散, 且产物中存在大量杂质. 而当以尺寸为5 μm的聚苯乙烯微球为核时, MCM-41纳米粒子紧密地包覆在聚苯乙烯微球表面, 复合结构微粒之间只有少量桥连物, 且产物中杂质很少.     

基于多壁碳纳米管/二茂铁接枝壳聚糖的核/壳结构组合物多层膜电极的组装及其电催化

以聚二烯丙基二甲基氯化铵(PDDA)修饰的玻碳电极(GCE)为基础电极, 利用静电层-层自组装的方法将多壁碳纳米管/二茂铁接枝壳聚糖的核/壳结构组合物(MWCNTs@CHIT-Fc)和聚苯乙烯磺酸钠(PSS)在该电极表面进行交替多层组装. 用循环伏安(CV)、紫外-可见光谱(UV-Vis)和扫描电子显微镜(SEM)等方法对组装过程进行了跟踪表征. 用CV方法研究了抗坏血酸(AA)在该多层膜电极上的电催化氧化. 研究结果表明, 当MWCNTs@CHIT-Fc为6个双层时, AA在该修饰电极上的氧化峰电位与裸GCE相比降低了约0.4 V. 用控制电位电流法研究了不同MWCNTs@CHIT-Fc双层时AA的电流响应. 用该电极测定了AA的灵敏度, 检测限及线性范围等性能参数可通过控制组装的MWCNTs@CHIT-Fc双层数进行调节.     

二氧化硅纳米粒子薄膜的制备及光学性能

以二氧化硅胶体和聚二烯丙基二甲基氯化铵(PDDA)为原料,利用静电自组装技术制备了PDDA/SiO2复合薄膜. TEM图象显示,薄膜中的SiO2纳米粒子为密堆积,薄膜均匀、致密;电子衍射实验结果显示,所组装的薄膜为非晶态膜.载玻片表面组装SiO2纳米粒子薄膜后,透射率随薄膜双层数增加呈现周期变化.薄膜具有增透作用,载玻片双面组装薄膜后在一定波长范围内的透射率可提高5％以上. PDDA/SiO2复合薄膜的光学性质主要由SiO2纳米粒子决定,每一双层的平均物理厚度小于SiO2纳米粒子的粒径,薄膜中存在层间穿插现象,逐层组装的复合薄膜具有单层光学薄膜的特性.     

Ultrathin Multilayer Films Incorporating Keggin-type Heteropolyanion Clusters

In recent years, there has been considerable interest in the fabrication of self-assembled ultrathin multilayer films, because of their availability to form nanostructured materials with tailored architecture and properties1. The layer-by-layer (LBL) self-assembly, initially developed for pairs of oppositely charged polyelectrolytes2, is an unusually simple and versatile technique to built up of ultrathin multilayer films. A special feature of the multilayer films is that the composition, t…     

Nanopatterning and fabrication of memory devices from layer-by-layer poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) ultrathin films

A write-read-erasable memory device was fabricated on layer-by-layer (LbL) ultrathin films prepared from poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT-PSS) and poly(diallyldimethylammonium chloride) (PDDA). By use of current-sensing atomic force microscopy (CS-AFM), nanopatterns were formed by applying a bias voltage between a conductive tip (Pt-coated Si3N4 cantilever) in contact with the polymer film and gold substrate. The dependence of the nanopatterns on film thickness, applied bias, and writing speed was studied. Moreover, the height of the patterns was 3-5 times higher than the original thickness of the films, opening the possibility for three-dimensional nanopatterning. The ability of the patterns to be erased after nanowriting was also investigated. By comparing the I-V characteristics under ambient conditions and under N2 environment, a joule-heating activated, water meniscus-assisted anion doping mechanism for the nanopatterning process was determined. Write-read-erase memory device capability was demonstrated on the nanopatterns.     

Assembly of Electroactive Ordered Multilayer Films of Cobalt Phthalocyanine Tetrasulfonate and Polycations

Films with alternating layers of the anion cobalt phthalocyanine tetrasulfonate (CoIIPcTS4-) and cationic polydimethyldiallylammonium chloride (PDDA) were prepared by electrostatic layer-by-layer adsorption. Quartz crystal microbalance and optical studies demonstrated formation of smooth ultrathin films with a linear increase in thickness with the number of deposition steps. Films containing 1, 2, 3, 4, and 5 bilayers of CoIIPcTS4-/PDDA on a gold electrode gave reversible, reproducible steady state cyclic voltammetry for the CoII/CoI redox couple with midpoint potential at -0.28 V vs a saturated calomel reference electrode. Voltammetry was controlled predominantly by charge transport processes in the film, even for films containing only a bilayer of PDDA/CoIIPcTS4-. The peak reduction current increased with the number of layers and showed a tendency to saturation after a deposition of 4-5 bilayers. Copyright 1999 Academic Press.     

Identification of Skim Milk Electroacidification Fouling: A Microscopic Approach

The self-assembly film fabricated via the layer-by-layer technique was studied by the dynamic contact angle (DCA) method (wilhelmy plate method). The used polyelectrolytes are poly(diallyl-dimethylammonium chloride) (PDDA), poly(etheleneimine) (PEI), diphenylamine-4-diazonium-formaldehyde resin (DR), 2-nitro-N-methyl-4-diazonium-formaldehyde resin (NDR), and poly(sodium-p-styrenesulfonate) (PSS). For the self-assembly systems of PDDA/PSS, PEI/PSS, DR/PSS, and NDR/PSS, their individual contact angle fluctuates regularly with the fabrication of each layer, while the magnitude of different systems' contact angle depends on the participant polycation. The re-organization of components and the adjacent layer interpenetration are presented here to explain this phenomena. We also found that DR or NDR can adsorb itself via the layer-by-layer method to form multilayer film, and the hydrophobic interaction is put forward to effect this process. Moreover, the procedure of washing and drying after adsorption was studied and considered as a prerequisite for the successful fabrication, especially of the same charge carried components. Copyright 2001 Academic Press.     

Kinetic studies of glucose oxidase in polyelectrolyte multilayer films by means of scanning electrochemical microscopy (SECM)

Multilayer films of glucose oxidase (GOx) and poly(dimethyl diallyl ammonium chloride) (PDDA) prepared by layer-by-layer deposition were studied using scanning electrochemical microscopy (SECM). Aminated glass slides were coated with five bilayers of poly(styrene sulfonate) (PSS) and PDDA and used as substrates onto which GOx/PDDA multilayers were deposited. UV-Vis experiments confirmed multilayer growth, scanning force microscopic images provided morphological information about the films. SECM current-distance curves enabled the determination of kinetic information about GOx in GOx/PDDA multilayers as a function of layer number, film termination, inert covering layers, and enzyme substrate concentration after fitting to numerical models. The results indicate that only the topmost layers contributed significantly to the conversion. An odd-even pattern was observed for PDDA-terminated films or GOx-terminated films that correlated with morphological changes.     

Self assembly and optical properties of dendrimer nanocomposite multilayers

Ultrathin multilayers are important for electrical and optical devices, as well as for immunoassays, artificial organs, and for controlling surface properties. The construction of ultrathin multilayer films by electrostatic layer-by-layer deposition proved to be a popular and successful method to create films with a range of electrical, optical, and biological properties. Dendrimer nanocomposites (DNCs) form highly uniform hybrid (inorganic-organic) nanoparticles with controlled composition and architecture. In this work, the fabrication, characterization, and optical properties of ultrathin dendrimer/poly(styrene sulfonate) (PSS) and silver-DNC/PSS nanocomposite multilayers using layer-by-layer (LbL) electrostatic assembly techniques are described. UV-vis spectra of the multilayers were found to be a combination of electronic transitions of the surface plasmon peaks, and the regular frequency modulations attributable to the multilayered film structure. The modulations appeared as the consequence of the highly regular and non-intermixed multilayer growth as a function of the resulting structure. A simple model to explain the experimental data is presented. Use of DNCs in multilayers results in abrupt, flat, and uniform interfaces.     

聚电解质PSS/PDDA分子沉积膜表面性能研究

PSS PDDAMD膜紫外 可见吸光度与层数呈线性关系 ,其延长线基本为零证实了是一单分子层层状沉积过程 ;利用接触角测量仪跟踪MD膜沉积过程 ,其结果表明 ,层数较少时PSS PDDAMD膜表面润湿性呈“奇 偶”性规律变化 ,层数较多时规律性不明显 ,这说明聚电解质MD膜结构缺陷随着层数的增加有增大趋势 ;通过对原子力显微镜 (AFM)测定结果的分析 ,进一步证实了多层PSS PDDAMD膜存在结构缺陷 .     

Fabrication of Layer-by-layer Films of Polyhedral Oligomeric Silsesquioxanes

Layer-by-layer(LBL)self-assembly method was used to fabricate siliceous ultrathin films by using polyhedral oligomeric silsesquioxanes as building blocks.Ammonium salt of kctasilsesquioxane acid (OSi8) and bply(diallyldimethylammonium chloride)(PDDA) were altermately assembled onto CaF2 slide to form nanocomposite multilqyers,Linear build-up of the LBL films was confirmed by UV-Vis spectroscopy.IR spectrum suggests existence of OSi8 and PDDA in the LBL films.Atomic force microscopic surface topography of the LBL films indicates the OSi8 covers the entire surface of the topmost layer and shows a granular morphology.