磷钼酸/二氧化钛复合薄膜的结构及光致变色性能

利用溶胶-凝胶法制备了磷钼酸/二氧化钛（PMoA／TiO2）复合薄膜。通过红外光谱（FT-IR）、原子力显微镜（AFM）和X射线晶体衍射（XRD）对复合薄膜的组成和结构进行了表征。利用紫外／可见吸收光谱（UV-vis）和电子自旋共振光谱（ESR）对复合膜的光致变色性能进行了研究。FT-IR分析结果表明,Keggin结构磷钼酸分子的基本结构在复合薄膜中仍然存在,在PMoA与TiO2界面间形成了Mo—O—Ti键电荷转移桥。AFM结果表明复合前后TiO2薄膜以及复合膜光照前后的表面形貌发生了显著变化。复合膜具有可逆的光致变色性质,在紫外光照下,复合薄膜由无色变为蓝色,蓝色薄膜在空气中暗处放置后可恢复为无色。ESR结果表明TiO2受紫外光激发产生光生电子,导致PMoA发生光还原反应,生成杂多蓝。PMoA／TiO2体系的光致变色过程是按照电子迁移的机制进行的。     

石墨烯分散液及其组装膜的性能

通过对比表面活性剂十二烷基硫酸钠(SDS)和聚乙烯醇(PVA)对石墨烯的分散能力,发现SDS可有效避免石墨烯片层之间的团聚,使得石墨烯在水溶液中分散得更加均匀.将浓度分别为0.39和0.30 mg/m L的石墨烯(G)和石墨烯片(GF)的SDS分散液旋涂在ITO电极表面制备出G膜和GF膜.透射电子显微镜和原子力显微镜观测结果表明,两类石墨烯膜均呈现出纱状透明的片状结构,同时具有石墨烯特有的褶皱.在石墨烯膜上继续进行钌配合物分子膜的自组装实验,得到G/Ru复合膜和GF/Ru复合膜.采用循环伏安法及紫外-可见吸收光谱法对石墨烯复合膜进行光电化学分析,结果表明石墨烯膜与钌配合物分子膜的复合可有效加强薄膜对太阳光的吸收.     

Na-MMT掺杂对PMA/PVP复合膜结构及光致变色性能的影响研究

将钠基膨润土(Na-MMT)掺入磷钼酸/聚乙烯基吡咯烷酮(PMA/PVP)体系中,利用透射电子显微镜(TEM)、原子力显微镜(AFM)、红外光谱(FTIR)、热重-差热(TG-DTA)、紫外-可见吸收光谱(UV-Vis)、X射线光电子能谱(XPS)等手段对复合薄膜的结构、热稳定性和光致变色性能进行了研究.红外光谱结果表明keggin结构磷钼酸和聚乙烯吡咯烷酮的基本结构在复合膜中仍然存在,复合膜中高分子与质子结合,以阳离子的形式与杂多阴离子成盐.Na-MMT的掺杂未对复合膜中PVP和PMA间的相互作用产生影响,但其掺杂提高了复合膜的热稳定性.在紫外光照下,复合膜由无色变为蓝色,杂多酸被还原产生杂多蓝.Na-MMT的掺杂降低了复合膜的光致变色响应性,这是由于多酸分子与钠基膨润土之间发生阳离子交换作用导致的.     

Gemini对PVA分散螺吡喃有机凝胶薄膜光致变色行为的调控

通过共溶剂-乳化-溶剂挥发法制备了聚乙烯醇(PVA)分散螺吡喃(SP)光致变色有机凝胶薄膜(PDPGSP),采用双子型表面活性剂六亚甲基-1,6-双十二烷基二甲基溴化铵(Gemini)调控聚合物/有机凝胶界面相互作用,系统研究了薄膜光致变色行为、褪色行为、微观结构形貌、力学性能及耐疲劳性能.结果表明,PDPG-SP薄膜表现出良好的光致变色行为与类溶液的褪色行为,SP在薄膜中褪色速率与聚丙二醇(PPG)溶液相近;薄膜具有优异的力学性能,其弹性模量与拉伸强度分别高达~547和~23.5 MPa;经过10次变色-褪色循环后,薄膜最大吸收波长处吸光度A衰减了约35%,相比以PVA1为表面活性剂(衰减约53%),耐疲劳性明显提升.Gemini有序聚集过程中头基分离力的有效阻抑,抑制了PVA/有机凝胶界面对SP的锚定,使更多SP分子分布于自由异构的有机凝胶微环境,提高薄膜褪色速率,同时可逆异构分子数量的增加,使薄膜耐疲劳性提高.     

镶嵌钨硅酸的新型有机-无机纳米复合薄膜的制备及光致变色性能研究

将超分子自组装技术与Sol-gel过程相结合,制备了镶嵌Keggin结构钨硅酸的MAAM/VTEOS/TEOS纳米复合薄膜,并采用IR,XRD和TG-DSC等方法对薄膜进行了结构表征.在复合薄膜光照变蓝后,通过UV-Vis和ESR光谱对薄膜的光致变色性能及其机理进行了研究.结果表明,钨硅酸在复合网络中仍保持Keggin结构,与有机-无机复合基体中的-NH₂通过氢键发生强烈的相互作用,经紫外光照后发生电荷转移,[SiW₁₂O₄0]₄^-被还原为[SiW₁₂O₄0]₅^-,同时产生氨基自由基.褪色过程则与氧气存在与否有关,实验结果表明,该薄膜具有良好的光致变色性能,对光有较快的响应恢复速度和良好的可逆重复性.     

氢键复合膜在酸性溶剂中溶解研究

以聚乙烯吡咯烷酮(PVPON)、聚丙烯酸(PAA)分别为氢键受体和氢键给体,利用层层组装技术制备高分子氢键复合膜.利用紫外-可见光谱、红外光谱及原子力显微镜研究了PVPON/PAA氢键复合薄膜在甲酸、三氟乙酸、磷酸、多聚磷酸中的解离过程.氢键复合薄膜在酸性溶剂中解离速率的快慢为三氟乙酸磷酸甲酸.在不同的酸性溶剂中,氢键复合膜的解离机理不同.三氟乙酸体系主要与薄膜中的PAA发生作用,致使PAA与PVPON之间的氢键解离,从而薄膜溶解.而磷酸和多聚磷酸体系则主要与PVPON发生作用,使薄膜溶解.多聚磷酸与磷酸相比,具有更多质子给体基团,与PVPON作用是体现出协同效应.甲酸和PAA同属于羧酸,甲酸分子很难取代PAA,与PVPON形成氢键,其溶解速度非常缓慢.     

燃料电池用聚乙烯醇基碱性聚合物电解质膜的制备及其性能

通过在不同浓度KOH溶液中进行掺杂,制备出了聚乙烯醇(PVA)、聚乙烯醇/聚乙烯吡咯烷酮(PVA/PVP)和聚乙烯醇/聚乙二醇二甲醚(PVA/PEGDE)碱性聚合物电解质膜详细考察了膜的外观形貌、微观结构、热稳定性、离子电导率和化学稳定性等.结果表明,PVA与PVP以及PEGDE具有很好的相容性,所制备的复合膜断面致密...     

溶胶-凝胶法制备Tb-PDA/PVA薄膜及其荧光性能

采用溶胶-凝胶法制备了铽(Ⅲ)-吡啶-2,6-二羧酸/聚乙烯醇(Tb-PDA/PVA)发光薄膜,其结构经IR,差热分析,原子力显微镜及荧光光谱表征.分析结果表明:薄膜表面平整,PVA中的纳米Tb-PDA(平均粒径为90 nm)分散均匀,在270 ℃以下具有良好的热稳定性.在紫外光照射下,薄膜发出较强的绿色荧光,最大发射峰位于544 nm,归属于Tb3+的5D4→7F5跃迁.     

聚乙烯醇/纳米纤维素复合膜的渗透汽化性能及结构表征

将聚乙烯醇/纳米纤维素(PVA/NCC)复合膜应用于乙醇-水混合溶液的渗透汽化脱水过程,探讨了纳米纤维素对膜的溶胀性能、机械性能和渗透汽化性能的影响; 利用原子力显微镜(AFM)探测了纳米纤维素的形貌特征; 采用傅里叶变换红外光谱仪(FTIR)、扫描电镜(SEM)、差示扫描量热仪(DSC)和热重分析仪(TGA)对膜结构...     

基于静电纺丝技术的PET/PVA复合超滤膜制备条件的探索

采用多喷头静电纺丝技术制备了复合超滤膜,该复合超滤膜是以聚对苯二甲酸乙二酯(PET)无纺布为支撑层,PET/PVA复合纳米纤维膜为分离层,再用丙酮和水的混合溶剂处理得到致密分离层.采用扫描电镜法(SEM)、红外光谱法(FTIR)对复合膜表面进行表征,测试了复合超滤膜的抗水解性能.SEM结果表明,复合膜表面的PET纳米纤维的直径为960 nm,PVA纳米纤维的直径为320 nm,用不同比例的混合溶剂对复合超滤膜进行处理会产生不同的表面形貌,最佳的比例是w(丙酮)/w(水)=30/70.抗水解性能实验结果显示比较适宜的交联剂加入量为2 wt%,用该含量对复合膜进行交联,复合膜具有较好的抗水解性能,其中重量损失率为2.12%,溶胀度为3.62%.红外光谱分析表明,交联处理后,复合膜表面的—OH量大大减少,耐水性能提高,交联前后膜表面在—C O和C—O—C处的吸收峰有很大的区别.     

Structure and photochromic properties of molybdenumphosphoric acid/TiO<Subscript>2</Subscript> composite films

TiO₂ sol-gel composite films with dropping molybdenumphosphoric acid (PMoA) have been prepared by sol-gel method. The structure and constitute of composite thin films were studied with Fourier transforms infrared spectroscopy (FT-IR) atomic force microscopy (AFM), and X-ray diffraction (XRD) patterns, respectively. The photochromic behavior and mechanism of composite thin films were investigated with ultraviolet-visible spectra (UV-vis) and electron spin resonance (ESR). FT-IR results showed that the Keggin geometry of PMoA was still preserved inside PMoA/TiO₂ composite thin films, and a charge transfer bridge was built at the interface of PMoA and TiO₂ through the Mo-O-Ti bond. Surface topography of the composite film showed obvious changes before/after adding PMoA, and the surface topography of composite films showed obvious changes before/after irradiating as well. Composite thin film had reversible photochromic properties. Irradiated with UV light, transparent films changed from colorless to blue and they can bleach completely with ambient air in the dark. ESR results showed that TiO₂ were excitated by UV light to produce electrons, which deoxidized PMoA to produce heteropolyblues. The photochromic process of PMoA/TiO₂ system was carried through electron transfer mechanism.     

Structure and photochromic properties of molybdenumphosphoric acid/TiO_2 composite films

TiO_2 sol-gel composite films with dropping molybdenumphosphoric acid(PMoA) have been prepared by sol-gel method.The structure and constitute of composite thin films were studied with Fourier transforms infrared spectroscopy(FT-IR),atomic force microscopy(AFM),and X-ray diffraction(XRD) patterns,respectively.The photochromic behavior and mechanism of composite thin films were inves-tigated with ultraviolet-visible spectra(UV-vis) and electron spin resonance(ESR).FT-IR results showed that the Keggin geometry...     

Preparation and Photochromic Behavior of Novel Hybrid Inorganic—Organic Thin Film

A novel photochromic complex comprising of Keggin type tungstophosphate acid (PW12) and polyacrylamide(PAM) was prepared. FT-IR results showed that the Keggin geometry of PW12 was still preserved inside the composite, and a charge-transfer bridge was built between pw12 and PAM via hydrogen bond. AFM images indicated that surface topography of polymer matrix changed after adding PW12. Under UV irradiation, the film was reduced photochemically to yield a blue species, which was reversible in the present of oxygen in polymeric network.     

UV-light and visible-light photochromism of inorganic–organic multilayer films based on polyoxometalate and poly(acrylamide)

Novel UV-light and visible-light photochromic inorganic–organic multilayers composed of polyoxometalates (phosphomolybdic acid (PMoA)) and poly(acrylamide) (PAM) were prepared by the layer-by-layer (LbL) self-assembly method. The grown process, composition, surface topography, and photochromic properties and mechanism of the multilayer films were investigated by ultraviolet–visible (UV–vis) spectra, Fourier transform infrared spectra (FT-IR), atomic force microscopy (AFM), electron resonance spectra (ESR), and X-ray photoelectron spectra (XPS). Irradiation with UV-light or visible-light, the transparent films changed from colorless to blue and showed reversible photochromism. PMoA/PAM LbL films had higher photochromic efficiency under UV-light irradiation than visible-light irradiation. The bleaching process occurred when the films were in contact with O₂ in the dark or heated in air. The photochromic process of PMoA/PAM LbL film was in accordance with radical mechanism.     

Preparation and photochromic properties of pyrazolones/polyvinyl alcohol composite films

Novel photochromic composite films have been successfully fabricated by dispersing pyrazolone derivative:1,3-Diphenyl-4-(3-chlorobenzal)-5-hydroxypyrazole 4-phenylsemicarbazone (1a) into hydrosol of polyvinyl alcohol (PVA). The microstructure, photochromic behaviors and thermal bleaching properties were investigated by Raman spectroscopy, X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and ultraviolet-visible absorption spectroscopy (UV-vis). The results showed that 1a was not only blended but also well dispersed in the PVA polymer films with a suitable content of chromophore. Upon UV light irradiation, the composite films gradually changed from colorless to yellow and recovered fully to the initial state upon thermal bleaching. The time constants of photochromic reactions were almost the same as those of 1a observed in their crystalline state, indicating that the photochromic phenomenon is barely disturbed by the polymer matrix.     

三氧化钼与金纳米粒子复合薄膜光致变色特性的研究

MoO3具有光致变色特性,在大屏幕显示、高密度存储和灵巧窗等研究领域中具有潜在的应用前景^[1-3]。但由于MoO3薄膜中相当一部分光生载流子被复合,其参与变色反应的利用率很低,导致MoO3薄膜的变色效率较低,使其难以实现实用化。半导体表面修饰贵金属后,在半导体／金属界面上可形成Schottky势垒,这将有助于光生载流子的有效分离,从而提高其利用率。据此,本文采用在MoO3薄膜表面修饰金纳米粒子的方法,制备了MnO3和金纳米粒子的复合薄膜（MoO3/Au),变色试验结果表明,MoO3/Au复合薄膜的紫外和可见光变色效率相对MoO3薄膜均有较大的提高。     

Preparation and photochromism of Keggin-type molybdphosphoric acid/silica mesoporous composite thin films

Using tetraethoxysilane and 3-aminopropyltriethoxysilane as the silica sources, amino-functionalized organic/inorganic hybrid mesoporous silica thin films with 2-dimensional hexagonal structure have been synthesized by evaporation induced self-assembly process in the presence of cetyltrimethyl ammonium bromide templates under acid conditions. The Keggin-type molybdphosphoric acid (PMo) is incorporated into the mesoporous silica thin films with amino-groups by wetness impregnation, and the PMo/silica mesoporous composite thin films are obtained. The results of X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), and Fourier transform infrared (FTIR) spectra indicate the PMo molecules maintain Keggin structure and are homogeneously distributed inside mesopores. The composite thin films possess excellent reversible photochromic properties, and change from colorless to blue under ultraviolet irradiation. The photochromic mechanism of the composite thin films is studied by ultraviolet-visible (UV-vis), electron spin resonance (ESR) and X-ray photoelectron spectroscopy (XPS) spectra. It is shown that intervalence charge transfer (IVCT) and ligand-to-metal charge transfer (LMCT) are the main reasons of photochromism. PMo anions interact strongly with amino-groups of the mesoporous suface via hydrogen bond and electrostatic force. After ultraviolet irradiation, the charge transfer occurs by reduction of heteropolyanions accompanying the formation of heteropolyblues with multivalence Mo(VI, V), and the bleaching process of composite thin films is closely related to the presence of oxygen.     

Properties of Poly(Vinyl Alcohol)‐Based Composite Membranes for Direct Methanol Fuel Cell Applications

The feasibility of poly(vinyl alcohol)(PVA)/sulfosuccinic acid(SSA)/heteropolyacid (HPA) composite membranes was investigated to apply for direct methanol fuel cells (DMFC). The composite membranes were prepared by the solution casting method and their properties were examined. The FTIR spectra showed that the Keggin unit of HPA was preserved in the composite membranes and that specific interactions were involved between PVA and HPA. The composite membranes showed uniform distribution of PWA particles in the PVA/SSA/PWA composite membranes by FE‐SEM. The HPA bleeding out was observed to decrease with increasing HPA concentration. The proton conductivity of PVA/SSA/HPA composite membranes improved at low HPA concentration (5‐10 wt.%), while those properties decreased as HPA concentration increased over 10 wt.%.     

Photochromic inorganic-organic multilayer films based on polyoxometalates and poly(ethylenimine)

Novel photochromic inorganic-organic multilayers composed of polyoxometalates and poly(ethylenimine) have been prepared by the layer-by-layer (LbL) self-assembly method. The growth process, composition, surface topography, and photochromic properties of the multilayer films were investigated by UV-visible and Fourier transform infrared spectroscopy, atomic force microscopy, electrospin resonance (ESR), and X-ray photoelectron spectroscopy (XPS). Irradiated with ultraviolet light, the transparent films changed from colorless to blue. Moreover, the blue films showed good reversibility of photochromism and could recover the colorless state gradually in air, where oxygen plays an important role in the bleaching process. On account of the ESR and XPS results, parts of W6+ in multilayers were reduced to W5+, which exhibited a characteristic blue; a possible photochromic mechanism can be speculated. This work provides basic guideline for the assembly of multilayers with photochromic properties.     

光响应性偶氮聚电解质自组装研究

将3种侧链带有不同偶氮生色团的聚电解质,用逐层浸渍的方法使其组装成多层膜.利用原子力显微镜(AFM)研究了自组装膜的表面形貌以及随着组装层数增加的变化.详细研究了在紫外光的照射下,薄膜内偶氮生色团由反式到顺式构型的光响应转变,以及在暗室中由顺式回复到反式构型的回复特性.与自组装膜的光响应性和相应的旋涂膜进行比较发现,其中的PNAPE/PDAC自组装膜没有明显的光色效应,而PEAPE/PDAC,PPAPE/PDAC具有明显的光色效应.在暗室中,随生色团的结构不同和在不同的凝集态中,由顺式回复到反式构型的速率明显不同.