Some Dynamic Properties of the Interface

Russian Journal of General Chemistry - By means of an original technique, two dynamic effects at the interface, viscoelasticity and spreading, were considered. The first effect was studied with the...     

Electrical and Optical Properties of the Nitramine Group and Molecular Structure of Some N-Nitramines

The electrical and optical properties (dipole moment, electrooptical and optical Kerr constants, molecular polarizability anisotropy, polarizability tensor, molecular refraction) of N,N-dimethylnitramine as the simplest N-NO₂ derivative were studied by a set of experimental and theoretical methods with the aim to determine the components of the polarizability ellipsoid of the N-NO₂ group and develop a valence-optical scheme for calculating the optical and electrooptical parameters of N-NO₂ compounds. Conjugation of the p electrons of the imide nitrogen atom with the electrons of the nitro group results in deviation of the properties of N,N-dimethylnitramine from the additive values. Comparative evaluation of the parameters of the Csp³-NO₂, Csp²-NO₂, and N-NO₂ groups was made.     

Studies of the Influence of Polyelectrolyte Adsorption on Some Properties of the Electrical Double Layer of ZrO2- Electrolyte Solution Interface

An influence of the molecular weight of the polymer and inorganic contaminations of zirconia on the adsorption and electrokinetic properties on ZrO₂-electrolyte solution interface was studied. Two polymers were used; polyacrylic acid (PAA) and polyacrylamide (PAM). On the basis of the obtained dependencies, main factors responsible for observed changes of zeta potential and surface charge of washed and contaminated ZrO₂ were determined. It was showed, that the change of ionic structure in the Stem layer depends on the number and arrangements of-COOH groups in PAA and PAM macromolecules. These groups are responsible for the conformation of polymer chains near the surface and have direct influence on the amount of the adsorbed polyelectrolyte. The inorganic ions, present on the surface of the oxide, blocking some part of active sites, making them inaccessible for adsorbing by carboxylic groups polymer chains. That makes the adsorption on the contaminated oxide lower than on the washed one. From the comparison of the determined values of the diffuse layer charge and surface charge, the main factor influencing the zeta potential changes at different pH, molecular weight and polymer concentration was determined. Also was demonstrated, that the contaminations of the solid are reason for considerable shift of pH_pzc in relation to pH_icpof the zirconia. Thickness of the adsorption layers and free energies of the adsorption of polyacrylic acid and polyacrylamide on the surface of ZrO₂ were calculated.     

天然聚多糖的溶解机理及溶液性质

21世纪"绿色"化学已成为各国科学界和工业界研究与开发的方向.天然高分子中纤维素、甲壳素等聚多糖来源丰富,是重要的可再生资源,也是未来主要的化工原料之一.由于大量的分子内和分子间氢键,它们的溶解长期以来都是非常棘手的问题.另一方面,聚多糖的结构非常复杂,只有弄清楚其链构象和溶液性质,才可能进行合理的分子设计,实现其更好的应用.本文简要介绍了本课题组用碱/尿素水体系低温溶解纤维素和甲壳素等天然高分子的机理和溶液中分子链构象,以及活性多糖在水溶液中的链构象和溶液性质的研究进展.     

Separation of Electrical and Optical Energy Gaps: Selectively Adjusting the Electrical and Optical Properties for a Highly Efficient Blue Emitter

The design concept of separation of optical and electrical bandgap for wide bandgap materials is further developed in DCzSiPI. The HOMO/LUMO levels can be tuned by incorporation of PI and DCz substituents. The tetraphenylsilane core avoids the intramolecular charge transfer from DCz to PI (DCz=dimer carbazole, PI=phenanthro[9,10‐d]imidazole). The allowed transitions are found to be from HOMO?1 to LUMO providing DCzSiPI with sufficient bandgap.     

聚苯胺-富勒烯复合膜的光电响应

通过溶液共混方法制备了聚苯胺（PANI）-富勒烯复合膜, 并用IR、XRD、UV-Vis等技术对其进行表征.红外光谱表明聚苯胺与C60之间存在相互作用且表现为掺杂态聚苯胺红外谱图样.X射线衍射表明复合体材料的结晶性能增强.光致发光谱表明聚苯胺与C60分子之间存在有效光诱导电荷分离现象.光电响应实验表明复合体薄膜的光吸收增强, 光电流增大, 说明聚苯胺-富勒烯复合膜受光照射后发生了光诱导电荷分离现象, C60掺杂聚苯胺有助于改善光伏特性.     

硫化镉纳米薄膜的制备及其光电性能

CdCl2·2H2O与S在N,N-二甲基甲酰胺中制备纳米CdS薄膜,其结构经UV-Vis,FL,XRD,SEM,Ⅳ表征.n(CdCl2)∶n(S) =0.065∶0.01,反应电压5V,于80℃(水浴温度)反应5 min制得CdS薄膜的光电性能、稳定性及薄膜结构均较好.     

吖啶酮类衍生物的光电性质研究

测定了8个吖啶酮类衍生物的紫外吸收光谱、荧光光谱和荧光量子产率,以研究它们的结构与光学性质之间的关系,用循环伏安法测出它们各自的电子势．发现吖啶酮类衍生物都具有较高的电子亲和势,表现出比常用的电子传输材料2-(4-联苯基)-5-(叔丁苯基1—1,3,4-二唑(PBD)更容易被还原的优良电化学性能。     

Optical and Electrical Properties of Polymerizing Plasmas and Their Correlation with DLC Film Properties

Diamond-like carbon (DLC) films were grown from radiofrequency plasmas of acetylene-argon mixtures, at different excitation powers, P. The effects of this parameter on the plasma potential, electron density, electron temperature, and plasma activity were investigated using a Langmuir probe. The mean electron temperature increased from about 0.5 to about 7.0 eV while the mean electron density decreased from about 1.2 × 10⁹ to about 0.2 × 10⁹ cm^–3 as P was increased from 25 to 150 W. Both the plasma potential and the plasma activity were found to increase with increasing P. Through actinometric optical emission spectrometry, the relative concentrations of CH, [CH], and H, [H], in the discharge were mapped as a function of the applied power. A rise in [H] and a fall in [CH] with increasing P were observed and are discussed in relation to the plasma characteristics and the subimplantation model. The optical properties of the films were calculated from ultraviolet-visible spectroscopic data; the surface resistivity was measured by the two-point probe method. The optical gap, E _G, and the surface resistivity, _s, fall with increasing P. E _G and _s are in the ranges of about 2.0–1.3 eV and 10¹⁴–10¹⁶ /, respectively. The plasma power also influences the film self-bias, V _b, via a linear dependence, and the effect of V _b on ion bombardment during growth is addressed together with variation in the relative densities of sp² and sp³ bonds in the films as determined by Raman spectroscopy.     

Dynamic Covalent Synthesis of Donor–Acceptor Interlocked Architectures in Solution and at the Solution:Surface Interface

Despite advances in the range of mechanically interlocked architectures that can be synthesized and operated as supramolecular machines, motors and sensors in solution, in many cases their synthesis is laborious and expensive requiring long multistep pathways with extensive purification at each stage. Dynamic covalent chemistry has been shown to overcome problems with traditional kinetically controlled synthetic approaches that often afford low yields of interlocked architectures due to irreversible formation of non‐interlocked by‐products. Herein, we describe the use of reversible disulfide exchange reactions as a means to assemble catenanes and rotaxanes in organic solutions. Moreover, the application of this thermodynamic approach to assemble interlocked architectures at the solution:surface interface, specifically polymer resins, is discussed.     

火焰原子吸收法连续测定镉镍浸渍液中镁钾钙铁

火焰原子吸收光谱法连续测定镉镍浸渍液中镁、钾、钙和铁是一种非常有效的仪器分析方法 ,该方法灵敏度高 ,分析精度好 ,分析速度快。以往采用的比色法和容量法 ,不仅操作繁杂 ,分析要求也极为严格 ,稍有不慎便会带来误差。本文用火焰原子吸收光谱法对镉镍浸渍液中镁、钾、钙和铁连续测定 ,并对测定条件、干扰因素进行了综合试验。各元素测定的相对标准偏差小于 1 .0 % ( n=1 0 ) ,标准加入回收率在 97%～ 1 0 3%内。方法简便、快速 ,适用于多元素镉镍浸渍液生产控制分析和样品系统分析。1　试验部分1 .1　仪器与试剂AA- 670型 ( Shimadzu)…     

基于ZnTMPP一维线性配位聚合物的合成及其光、电性能

以四(对甲基苯基)卟啉锌(ZnTMPP)配合物为核心配体,选择联吡啶、联苯胺和新合成的Schiff碱-双(4-吡啶甲醛)缩联苯胺为桥联配体合成了3种新型π-π共轭的一维线性配位聚合物。通过FT-IR、1 H-NMR、UV-Vis-NIR和XRD衍射谱图等对配体及配位聚合物结构进行了表征。考察了桥联配体的长度及结构对配位聚合物光学性能、电性能和结晶态的影响。结果表明,以Schiff碱-双(4-吡啶甲醛)缩联苯胺为桥联配体合成的配位聚合物在300~1 100nm有宽吸收带,并且可在低电位发生氧化还原反应,其满带和空带之间的能隙为0.19eV;以联吡啶和联苯胺为桥联配体的配位聚合物结晶度较好。     

Femtosecond Spectroscopy and Nonlinear Optical Properties of aza-BODIPY Derivatives in Solution

The fast relaxation processes in the excited electronic states of functionalized aza-boron-dipyrromethene (aza-BODIPY) derivatives ( 1 – 4 ) were investigated in liquid media at room temperature, including the linear photophysical, photochemical, and nonlinear optical (NLO) properties. Optical gain was revealed for nonfluorescent derivatives 3 and 4 in the near infrared (NIR) spectral range under femtosecond excitation. The values of two-photon absorption (2PA) and excited-state absorption (ESA) cross-sections were obtained for 1–4 in dichloromethane using femtosecond Z-scans, and the role of bromine substituents in the molecular structures of 2 and 4 is discussed. The nature of the excited states involved in electronic transitions of these dyes was investigated using quantum-chemical TD-DFT calculations, and the obtained spectral parameters are in reasonable agreement with the experimental data. Significant 2PA (maxima cross-sections ∼2000 GM), and large ESA cross-sections ∼10⁻²⁰ m² of these new aza-BODIPY derivatives 1–4 along with their measured high photostability reveal their potential for photonic applications in general and optical limiting in particular.     

Electrical and Optical Properties of MgO Thin Film Prepared by Sol-Gel Technique

MgO thin films with either (111) or (200) preferential orientation have been prepared on (100) Si substrates by sol-gel method after a heat-treatment at 800°C. The obtained (111) preferentially oriented MgO film has a dielectric constant of 7.0 with a loss factor of 5% and a dielectric strength higher than 8 × 10⁵ V/cm. The optical refractive index, which depends on the film thickness, is 1.71 when the film thickness is 260 nm. The surface structure of the Si substrate is believed to affect the preferential orientation of the sol-gel derived MgO film. Specifically, the microstructures at the interface indicate an interdiffusion of Mg, O, and Si between the film and the substrate.     

MWNTs/HDPE复合体系在太赫兹波段的光电性质

利用太赫兹时域光谱技术和电导测量研究了多壁碳纳米管/高密度聚乙烯(MWNTs/HDPE)复合体系的光电性质. 直流电导率结果表明, 复合体系的逾渗阈值在5%左右; 交流电导率则随频率的变化出现一个拐点, 拐点的位置与颗粒浓度以及导电颗粒的存在状态密切相关. 加入碳纳米管后, 复合体系在太赫兹波段的吸收系数和折射率均有很大的提高. 通过假定在此波段导电颗粒在聚合物中的介电行为类似于偶极子的弛豫, 利用Cole-Cole理论对复合材料的介电性质进行了解释.     

Ga掺杂纳米TiO2薄膜的制备及其光电特性

利用射频磁控溅射法在玻璃衬底上制备了Ga掺杂的TiO₂薄膜,并在真空中于550 ℃下进行了2 h的退火处理。采用XRD、SEM、UV-Vis和PL光谱对薄膜进行了表征。XRD结果提示,在溅射功率为200 W,室温下制备的TiO₂薄膜具有混晶结构,且退火后的晶粒有长大的趋势。SEM分析表明,掺Ga薄膜的颗粒分布得较为均匀并存在尺寸变小的趋势,且出现有利于提高光催化性能的岛状结构,其平均颗粒尺寸为50 nm。UV-Vis透过谱指出,掺Ga后的TiO₂薄膜吸收边发生了明显红移,且退火后进一步红移了10~50 nm。通过接触角的测量与计算可知,550 ℃退火2 h后的薄膜具有良好的亲水性。光催化降解结果表明：样品具有较强的光催化能力。当用低功率(15 W)紫外灯照射8 h后,Ga掺杂的纳米TiO₂薄膜样品对亚甲基蓝溶液的降解率最高可达到71.8%。     

Consequences of Chemical Modification on Optical and Solution Properties of Rodlike Polyamides

Abstract

Rodlike polyamides were substituted to 50–55% on the nitrogen atom of the amide group with benzyl, 1-naphthylmethyl, and 4-(1,3,6,8-tetrabromo-9-carbazolyl)-1-butyl groups using a standard literature procedure. The resulting polymers exhibit significantly lower isotropic refractive indices and enhanced solubility. Polymers composed of the isophthaloyl moiety, with or without N-substitution, also exhibit lower refractive indices and enhanced solubility when compared to their rodlike analogs. These differences in properties are due to a great extent to the large difference in conformational rigidity between the two polymer types.     

Synthesis,Molecular Structure,Optical Properties and Electrical Conductivity of Zwitterionic Ferrocenyldithiophosphonates

Ferrocenyldithiodiphosphetane [FcPS(μ‐S)]₂ [Fc = Fe(η⁵‐C₅H₄)(η⁵‐C₅H₅)] reacts with the aminoethanol derivatives 1‐ethyl‐3‐pyrrolidinol and 2‐(piperazin‐1‐yl)ethanol to give the zwitterionic (O‐ethylammonium)ferrocenyldithiophosphonates ( 2 ) and ( 3 ), which were fully characterized by elemental analysis, IR and NMR spectroscopy and mass spectrometry. The optical and electrical properties of 2 and 3 as well as those of the previously reported [FcP(S)S(OC₂H₄NHEt₂)] ( 1 ) were studied. A molecular structure determination of 1 is also reported.     

Optical and Electrical Properties of Ferroelectric SBN Thin Films Prepared by Sol-Gel Process

Strontium barium niobate thin films were prepared by sol-gel method on various substrates using an improved process, two-step heating process. The two-step heating process applies an additive heat-treatment before crystallization for enhancement of the densification and the nucleation of films. Also, highly c-axis oriented SBN thin films with various compositions were obtained on MgO(100) and Pt(100)/MgO(100) substrates. Their optical and electrical properties such as optical propagation loss, refractive index, P-E hysteresis, and dielectric constant, were characterized as a function of the film composition.