Nonlinear Optical Properties of Semiconductor-Doped Sol-Gel Waveguides

Thin silica-titania films doped with CdS and PbS nanocrystals have been prepared by the sol-gel route. Their nonlinear properties have been studied using the techniques of degenerated four-wave mixing and m-lines with picosecond (ps) and nanosecond laser pulses. Depending on wavelength, doping level, and laser pulse duration, high negative nonlinearity was found for CdS-doped (n₂ = -2 x 10^-8 cm² per kW) and PbS-doped films (-10^-10 to -2 x 10^-7 cm² per kW). The response time of the nonlinearity was below 35 ps. Saturation of the nonlinearity was observed. Straight, monomode channel waveguides have been fabricated on these films. The influence of MIE-scattering due to the nanoparticles is investigated.     

亚相金属离子与两亲配体LB膜相互作用的研究

The complex formation of 2-hexadecylcarbamoyl-8-hydroxyquinoline(HHQ) monolayers at the air/water interface by reaction with metal ions from the subphase was investigated using X-ray photoelectron spectroscopy. The formation of HHQ-metal complexes leads to the appearance of new peaks assigned to the metal ions. The information on stoichimoetry provided by XPS indicated that a metal ion is coordinated by two HHQ molecules for La3+ and Cd2+ ions, but by one HHQ molecule for Mn2+ and Ni2+ ions.     

Growth of thin polymer films containing side-chain azo-dye analyzed by atomic force microscopy

Thin films containing both the azo-dye disperse red 1 (DR1) and the poly(methylmetacrylate) (PMMA) or the poly(phenylenevinylene) (PPV) are deposited by Langmuir-Blodgett and spin coating techniques on various substrates. The morphology, surface structure and growth pattern of the azo-dye-polymers were studied by atomic force microscopy. Nucleation and growth processes are responsible for the generation of different structures. The spin coated films were additionally oriented using the electric field poling method (corona poling). The film homogeneity is improved by this method in all cases. Due to the polar character of DR1 molecules, rod-like sub-structures are observed after the corona poling process in DR1-MMA films. The indium tin oxide surface enhances reorientation of the azo-dye-polymer molecules during corona poling and results in a significant reduction of the surface roughness.     

Alginate-magnesium aluminum silicate films for buccal delivery of nicotine

Sodium alginate-magnesium aluminum silicate (SA-MAS) dispersions with nicotine (NCT) were prepared at different pHs and characterized for the particle size and zeta potential, NCT adsorbed by MAS, and flow behavior before film casting. The physicochemical properties, NCT content, in vitro bioadhesive property, and NCT release and permeation of the NCT-loaded SA-MAS films were investigated. This study showed that incorporation of NCT into the SA-MAS dispersions caused a change in particle size and flow behavior and that NCT could be adsorbed by MAS. The formation of protonated NCT at acidic and neutral pHs could interact with negatively charged MAS via an electrostatic force, resulting in the formation of NCT-MAS flocculates/complexes that could act as microreservoirs in the films. The NCT-loaded SA-MAS films prepared at pH 5 yielded the highest NCT content due to non-significant loss of NCT during drying. Moreover, pH of the preparation also affected the crystallinity and thermal properties of the films. The NCT release and permeation across the mucosal membrane of the films could be described using a matrix diffusion controlled mechanism. In addition, the NCT-loaded SA-MAS films also possessed a bioadhesive property for adhesion to the mucosal membrane. This finding suggests that the NCT-loaded SA-MAS films composed of numerous NCT-MAS complexes as microreservoirs demonstrated a strong potential for use as a buccal delivery system.     

Langmuir-Blodgett films of cyclopalladated ferrocenylimine: preparation, characterization, and application in Suzuki coupling reaction

Langmuir monolayer and Langmuir-Blodgett (LB) films of cyclopalladated ferrocenylimine 1 were prepared and characterized. The surface pressure (π)-area (A) isotherm of complex 1 indicated the formation of highly condensed monolayer on the subphase. Ultraviolet-visible (UV-vis) and Fourier transform infrared (FTIR) spectroscopy showed that complex 1 monolayer was transferred successfully onto solid supports. Atomic force microscopy (AFM) image suggested that LB films transferred on the solid substrate were well-ordered, homogeneous. Cyclic voltammograms of LB films deposited on glassy carbon electrodes showed quasi-reversible oxidation/reduction waves of ferrocene moiety. From the average thickness of monolayer, the hydrocarbon chain could be fairly directed perpendicular to the substrates. Finally, LB films of complex 1 presented a largely improved catalytic efficiency for Suzuki reaction with respect to its cast films and homogeneous reactions under the same conditions. The results might have an implication on the catalytic mechanism of this reaction.     

CCD紫外增强薄膜旋涂法工艺优化

在硅基探测器的入射窗上制备荧光下转换薄膜,是一种有效降低成本的紫外荧光增强技术。从理论上探讨了由聚二甲基硅氧烷与颜料黄101混合胶体的紫外荧光薄膜旋涂工艺参数与性能之间关系,搭建紫外荧光薄膜应用于光谱分析的性能测试实验平台,对紫外荧光增强薄膜旋涂工艺参数质量配比、旋涂转速进行优化。光谱分析探测器有两个主要指标,光谱响应灵敏度和光谱分辨率,分析与实验结果表明,利用旋涂法制备紫外增强荧光薄膜,旋涂转速将直接影响薄膜的厚度、表面粗糙度和荧光物质的分布,从而影响光谱分析系统的分辨率;紫外荧光增强薄膜的增强效率与荧光溶剂聚二甲基硅氧烷与荧光物质颜料黄101的质量比密切相关,质量比低无法满足对紫外响应效率的提高,但高质量比,荧光物质处在聚集态荧光自猝灭严重,也不利于增强薄膜的紫外响应效率。最终,在薄膜旋涂工艺优化的基础上,旋涂转速2 500～3 000 r·min-1,荧光物质与荧光溶剂质量比为7∶100制备出紫外荧光增强薄膜。汞灯特征光谱测试结果表明该薄膜313 nm紫外波长处探测响应灵敏度提高了1.6倍左右,对比分析镀膜前后特征光谱的半波带宽,镀制紫外增强荧光薄膜对其影响很小。     

The impact of chemical composition on the degradation kinetics of poly(lactic-co-glycolic) acid copolymers cast films in phosphate buffer solution

We have investigated the in vitro degradation of poly(lactic-co-glycolic) acid copolymer with different lactic to glycolic ratio: 50:50, 65:35, 75:25, 95:05 and 100:00 (mol. %). The degradation studies were performed on solvent cast films of controlled thickness and shape. The samples were incubated at 37 °C in phosphate buffered saline solution. The degradation was followed using potentiometry, light microscopy, gravimetry, size exclusion chromatography and differential scanning calorimetry. The same degradation process, as discussed in detail in our previous article for PLGA 50:50 (E. Vey et al., J. of Polym. Deg. and Stab. 2008, 93, 1896-1876), was observed for all the samples investigated, however the time scale over which the different events/degradation steps were observed increased with increasing lactic content of the polymer. The glass transition temperatures of the films increase with lactic content and are thought to have a significant impact on the rate of diffusion of water into the films - the higher the glass transition the slower the diffusion of water - and therefore on the degradation dynamics of the films. Kinetic parameters were extracted from the acid release, molecular weight and mass loss data. In each case linear correlations between the rate constants extracted and the lactic content of the polymer were found. The overall degradation rate of the films was found to decrease with increasing lactic content.     

超疏水多孔阵列碳纳米管薄膜

碳纳米管由于具有特异的力学[1] 、光学[2 ] 、电学[3,4 ] 和磁学性质[5] ,使其在锂离子电池[6 ] 和平板展示器[7] 等方面呈现出广泛的应用前景 .Ebbesen等[8] 对无序碳纳米管材料的浸润性进行了详细研究 ,发现其很容易被水润湿 .然而 ,阵列碳纳米管膜的浸润性研究尚未见报道 .固体表面的浸润性主要由表面化学组分和几何结构两方面控制 .通常 ,加大表面粗糙度可以增强其浸润性 [9～ 16 ] .近来 ,超疏水表面 (即与水的接触角大于 1 5 0°的表面 )的研究显示了广泛的应用背景[13～ 16 ] .这种表面通常可由增加表面粗糙度和降低表面能来制备[1…     

Microstructure of Mixed Cadmium Stearate and Behenate Langmuir-Blodgett Films

X-ray diffraction (XRD) was used to investigate the microstructure and phase separation of mixed multilayers of cadmium stearate (SA) and behenate (BA) deposited onto hydrophilic glass by the Langmuir-Blodgett technique. No unitary fatty acid diffraction peaks in the XRD spectra of the mixed LB films, which reveals that domains in these samples are small and uniform. The interplanar spacing of the mixed LB films changes with the ratio of BA to SA in a step-shaped curve, which suggests that with the changing of the ratio between BA and SA, only three kinds of ordered structure form in the mixed system, and each microstructure, in particular, the short chains against long chains meshed microstructure can be maintained in a certain ratio range . In addition, for the meshed microstructure, the alkyl chains of both SA and BA stand straight or may have exactly the same small tilted angle from the substrate normal, as is indicated by the symmetric and asymmetric stretching vibration of methylene (CH2) peaks which are at 2847.80 and 2914.37 cm-1respectively in the Fourier transform infrared (FT-IR) transmission spectra. The mixed system always goes through a longitudinal regularity decreasing process when BA/SA is out of the intermediate ratio range (BA/SA: 1/5-1/1), which is illustrated by the relative XRD intensity changing with the ratio of BA/ SA in a \W" shape. These results for the mixed LB films of BA/SA provide meaningful data for choosing the mixture ratio when fabricating composite films with special structure.     

有机金属聚合物/多酸纳米杂化LB膜的制备与光电性质研究

以含有共轭大π键的有机金属聚合物(OMP)作有机组分, 以Keggin结构和Dawson结构钨(钼)磷杂多酸作无机组分, 以十八胺为辅助成膜剂, 用LB技术制备了3种新型有机金属聚合物/十八铵/杂多阴离子OMP/ODA/HPA (HPA＝PMo₁₂, PW₁₂, P₂Mo₁₈)杂化LB膜. 用π-A曲线﹑UV-vis吸收光谱﹑荧光光谱﹑原子力显微镜(AFM)﹑扫描隧道显微镜(STM)和表面光电压谱(SPS)对标题LB膜的成膜性能及光电性质进行了研究, 结果表明标题杂化LB膜的崩溃压为26.8 mN/m, 在可见光区有较强的光电压响应, 并有好的发光性质. 当电压为±8.0 V时, 隧道电流是－0.1～－2.3 nA.