小角X射线散射技术在高分子表征中的应用

小角X射线散射(SAXS)技术是表征高分子材料微观结构的一种重要手段.当X射线穿过材料时,在材料不均一的电子云密度分布作用下,发生散射并形成特定的散射图案,使得我们可以根据特定的模型来反推材料的微观结构,并计算相关结构参数.SAXS特有的对微观结构的统计平均及无损探测使其成为了一种不可或缺的高分子材料微观结构分析手段....     

体积排除色谱技术在高分子表征中的应用

体积排除色谱(SEC)也称为凝胶渗透色谱(GPC),是利用多孔填料色谱柱将溶液中的高分子按照流体力学体积大小进行分离的一种液相色谱技术,主要用于测定各种天然和合成高分子的平均分子量及分子量分布.多检测SEC技术可同时获得经色谱柱分离后高分子各级分的含量、分子量、均方根回转半径、流体力学半径、特性黏数等参数,进而推断高分...     

高分子共混体系相分离相结构的光散射研究

本文基于Debye相关函数概念,引入一个有别于Debye型的相关函数Γ(r)=exp(-r/2D_m)cos(r/2D_m)。由此计算了散射光强变化,理论值和实验结果进行了比较,结果表明由新引入的相关函数得到的散射光强可很好地描述高分子共混体系相分离散射行为,在大波矢处具有I(q)～q~(-4)的渐近行为,相关函数的参数物理意义明确。     

光散射技术在研究高分子溶液和凝胶方面的应用

从溶液中的高分子、凝胶粒子及微乳胶粒子形态结构的表征和凝胶化过程、微乳液聚合及大分子缔合等动态过程的跟踪等方面的研究综述了近十几年来光散射技术在高分子溶液和凝胶领域的应用,并简单介绍了光散射技术的基本原理、发展简史和仪器及使用方法。     

小角X射线散射在高分子研究中的应用

本文综述了小角X射线散射理论,并介绍了小角散射在高分子溶液、结晶聚合物、嵌段共聚物和离聚物等研究中的应用.     

光散射在高分子溶液和聚集态研究中的应用

本文较为详细的综述了光散射在聚合物研究中某些领域内的应用，并着重介绍了光散射在聚合物凝胶领域、聚合物稀溶液中、聚合物相行为领域以及聚合物加工领域中的发展历史和研究现状。     

多检测GPC技术在高分子表征中的应用

多检测ＧＰＣ／ＳＥＣ在高分子表征中可获得比普通单检测ＧＰＣ丰富得多的重要信息,因而受到学术界和工业界的广泛重视。详细介绍了ＧＰＣ／ＲＩ／ＲＡＬＬＳ／ＤＶ多检测技术的检测原理,并介绍了应用实例。     

光散射技术在蛋白质晶体生长研究中的应用和进展

光散射技术广泛应用于生物大分子的晶体生长研究中,它包括静态光散射和动态光散射两种。利用静态光散射可以测定蛋白质溶液渗透的第二维里系数;利用动态光散射可以测定蛋白质溶液的平动扩散系数,获得溶液中蛋白质粒子的流体力学半径及分布情况,分离蛋白质结晶的成核与生长过程,研究大分子的聚集行为和晶体生长的动力学。借助光散射技术可以实现蛋白质晶体生长过程的动态控制。近些年光散射仪器向着小型化、轻便化的方向发展,光散射技术不断得到改进,日益完善,不仅用于地面实验,也应用于空间领域蛋白质晶体生长的研究中。     

动静态光散射技术在蛋白质研究中的应用进展

动静态光散射技术是研究蛋白质等大分子物质尺寸、分布、形态及构象的一种重要手段,以其快速、便捷、对样品无干扰等特点,逐步深入到生化、物理、医药病理等领域,具有良好的应用前景。本文简要阐述了光散射技术的发展,主要介绍了动静态光散射技术的原理,从流体力学半径、重均分子量、均方根回旋半径以及渗透第二维里系数4个重要的物理参数出发,对近年来动静态光散射技术在蛋白质研究中的应用进行了调研和综述,并对该技术的发展进行了展望。     

Scattering of Laser Light from Mixed Micelles

Dynamic and static scattering of light was employed to investigate mixed micelles of two homologous anionic surfactants-sodium octyl sulfate and sodium hexadecyl sulfate, above the phase boundary temperature and critical micelle concentrations (cmc). The results indicate that the mixed micelles change from prolate to sphcrical as the molar ratio SOS/SHS increases from 1 to 8. Below 1 or above 8, the formation of micelles is due to one surfactant dissolving the other.     

激光光散射研究天花粉蛋白的聚集过程

运用激光光散射技术研究天花粉蛋白在水溶液及不同浓度KSCN水溶液中的聚集过程．KSCN的加入能提高天花粉在水溶液中的稳定性. KSCN浓度大于0．5mol•L－1时，天花粉溶液透明、稳定，溶液中天花粉以单个分子与聚集体两种形式存在．聚集体主要是由约120个天花粉分子组成，平均流体力学半径Rh值约为49nm，在溶液中排列疏松，类似θ溶剂中的无规线团。     

Laser Light Scattering Study on Aggregation of Cellulose Diacetate in Acetone

We have investigated the properties of cellulose diacetate in solution by using laser light scattering. The cellulose diacetate molecules can form micelles and micellar clusters in acetone besides the individual chains. As the concentration increases, the average hydrodynamic radius （Rh） linearly increases, whereas the ratio of gyration radius to hydrodynamic radins 〈Rg〉/〈Rh〉 linearly decreases. It indicates that the micelles associate and form micellar clusters due to the intermolecular interactions.     

激光光散射表征聚N－异丙基丙烯酰胺的分子量分布

采用自由基聚合法合成了聚N-异丙基丙烯酰胺(PNIPAAM)样品,由激光光散射法(LLS),包括绝对累积散射光强的角度依赖性(静态LLS)和线宽分布的角度依赖性(动态LLS)表征了合成的PNIPAAM样品的分子量分布。通过对动态光散射测得的电场-电场时间相关函数的拉普拉斯变换,求得平动扩散系数分布G(D);结合静态和动态光散射测量的结果,即M_w和G(D),确定了PNIPAAM样品的平动扩散系数D对分子量M的标定关系式D=2.84×10^-4M^-0.55,并将G(D)转换成分子量分布F_w(M).     

时间分辨激光光散射测量系统

自选设计，装配了一套时间分辨的激光光散射测量系统，该系统摄像机，录像机，计算机和自编的软件实现了一体化的数据采集，显示和分析过程，本文给出了该系统的应用实例，球晶的光散射和环氧树脂的固化反应诱导的相分离过程。     

凝胶化反应中标度行为及凝胶化点关系

在苯乙烯(St)-二乙烯苯(DVB)自由基聚合的凝胶化反应过程中,定时取样,得到凝胶化点前后及直至反应终点的一系列溶胶样品,利用光散射技术研究了溶胶相的重均分子量M_w、尺寸均方旋转半径R_g的变化过程,建立了M_w、R_g和反应时间t的标度关系,并在此基础上提出一神新的准确求取凝胶化时间t_gel的方法.     

Hydrodynamic Radius Characterization of a Vinyl-Type Polynorbornene by Size-Exclusion Chromatography with a Static and Dynamic Laser Light Scattering Detector

Both absolute molecular weight and molecular sizes (radius of gyration and hydrodynamic radius) of a vinyl-type polynorbornene eluting from size-exclusion chromatography columns were determined by combined with a static and dynamic laser light scattering detector. The hydrodynamic radius of polymer fraction eluting from size-exclusion chromatography columns was obtained from dynamic laser light scattering measurements at only a single angle of 90° by introducing a correction factor. According to the scaling relationship between molecular sizes and molecular weight and the ratio between radius of gyration and hydrodynamic radius, the vinyl-type polynorbornene took a random coil conformation in 1,2,4-trichlorobenzene at 150 °C.     

Characterization of Carbon Based Nanoparticles Dispersion in Aqueous Solution Using Dynamic Light Scattering Technique

Characterization of physicochemical properties of nanoparticles in aqueous environment prior to conducting hazard studies is strongly recommended by many scientific organizations. In this work we studied the dissolution behaviour and physicochemical properties of carbon based nanoparticles in aqueous solution. The time evolution of the size distribution and the state of dispersion of carbon black and carbon nanotubes in physiological solution have been investigated by means of Dynamic Light Scattering technique. The influence of mechanical agitation such as sonication and stirring on the agglomeration state and particle size distribution has been investigated. However, such processes seem to have little or no effect as far as agglomeration is concerned.     

Structural Characterization of Biomaterials by Means of Small Angle X-rays and Neutron Scattering (SAXS and SANS), and Light Scattering Experiments

Scattering techniques represent non-invasive experimental approaches and powerful tools for the investigation of structure and conformation of biomaterial systems in a wide range of distances, ranging from the nanometric to micrometric scale. More specifically, small-angle X-rays and neutron scattering and light scattering techniques represent well-established experimental techniques for the investigation of the structural properties of biomaterials and, through the use of suitable models, they allow to study and mimic various biological systems under physiologically relevant conditions. They provide the ensemble averaged (and then statistically relevant) information under in situ and operando conditions, and represent useful tools complementary to the various traditional imaging techniques that, on the contrary, reveal more local structural information. Together with the classical structure characterization approaches, we introduce the basic concepts that make it possible to examine inter-particles interactions, and to study the growth processes and conformational changes in nanostructures, which have become increasingly relevant for an accurate understanding and prediction of various mechanisms in the fields of biotechnology and nanotechnology. The upgrade of the various scattering techniques, such as the contrast variation or time resolved experiments, offers unique opportunities to study the nano- and mesoscopic structure and their evolution with time in a way not accessible by other techniques. For this reason, highly performant instruments are installed at most of the facility research centers worldwide. These new insights allow to largely ameliorate the control of (chemico-physical and biologic) processes of complex (bio-)materials at the molecular length scales, and open a full potential for the development and engineering of a variety of nano-scale biomaterials for advanced applications.