Coupled measurement system for investigation of adsorption and complexing behaviour of polymers and nanoparticles in mortar and concrete: FFF-MALS-ICP-MS

现代水泥基粘结剂系统是以多组分组合物为特征的高性能材料。在硬化过程中，许多反应同时发生，例如溶解、成核和生长以及溶胶-凝胶反应。有机掺合料的部分未知结构、整个体系的复杂组成和早期反应产物的极小尺寸使得难以研究水泥水化早期阶段的过程。联邦航空局魏玛包豪斯大学的Finger Institut für Baustoffkunde（FIB）几十年来一直在国际层面上研究这些过程。应用耦合测量系统，其能够分别表征不同结构、组成和电荷的离子、聚合物、复合物、纳米颗粒和微米颗粒。该系统由分馏模块和检测模块组成。分馏模块由基本HPLC组件泵和自动进样器、可由GPC/SEC柱替换的不对称通量场流分馏通道（AF 4通道）以及带电场的AF 4通道组成。分离发生在开放通道（AF 4）中，其具有取决于颗粒的流体动力学半径的不对称流动轮廓，由此具有小半径的颗粒比较大半径的颗粒更早地被分离。如果向流体动力学流动轮廓另外施加电场，则颗粒根据它们的电泳迁移率分离。可通过比较两个色谱图（分别为AF 4和电AF 4）计算zeta电位。如果必须测定纯聚合物的分子量，则AF 4通道可以由GPC/SEC柱代替。检测模块由多角度激光散射检测器（MALS）、动态光散射检测器（DLS）、折射率检测器（RI）和电感耦合等离子体质谱仪（ICP-MS）组成。MALS用于确定颗粒的回转半径，其可用于计算聚合物的分子量。结合静态光散射，流体动力学半径提供了有关聚合物构象及其二级结构的重要信息。特殊RI检测器是一种高浓度灵敏度检测器，用于定量溶液中的聚合物。具有低检测限和高检测速度的在线耦合ICP-MS提供了关于颗粒的化学组成的信息。许多质量痕迹的瞬时记录应使人们有可能区分颗粒的有机和无机性质。应用的耦合测量系统集成到F.A.的化学分析实验室中。Finger建筑材料研究所由建筑化学和高分子材料主席（Osburg教授）以及建筑材料科学主席（Ludwig教授）运营。

Modern cement-based binder systems are high-performance materials that are characterized by a multi-component composition. During the hardening process many reactions occur simultaneously, for instance solution, nucleation and growth as well as sol-gel reactions. The partially unknown structure of organic admixtures, the complex composition of the entire system and the very small dimensions of the early reaction products make it difficult to study the processes in the early phase of cement hydration. The F.A. Finger Institut für Baustoffkunde (FIB) at the Bauhaus Universität Weimar has been researching these processes on an international level for decades. A coupled measurement system is applied for which is capable of characterizing ions, polymers, complexes, nanoparticles and microparticles of different structure, composition and charge respectively. The system consists of a fractionation module and a detection module. The fractionation module consists of the basic HPLC components pump and autosampler, an asymmetric flux-field flow fractionation channel (AF4 channel) which can be replaced by a GPC/SEC column as well as an AF4 channel with electric field. The separation takes place in an open channel (AF4) with an asymmetrical flow profile depending on the hydrodynamic radii of the particles, whereby particles with small radii elute earlier than larger ones. If an electric field is additionally applied to the hydrodynamic flow profile, the particles are separated according to their electrophoretic mobility. The zeta potential can be calculated by comparing both chromatograms (AF4 and electric-AF4 respectively). The AF4 channel could be replaced by a GPC/SEC column if the molecular mass of pure polymers has to be determined. The detection module consists of a multi-angle laser scattering detector (MALS), a dynamic light scattering detector (DLS), a refractive index detector (RI) and an inductively coupled plasma mass spectrometer (ICP-MS). The MALS is used to determine the gyration radii of the particles, which can be used to calculate the molecular weight of polymers. In combination with static light scattering, the hydrodynamic radius provides important information about the conformation of the polymer and its secondary structure. The special RI detector is a highly concentration-sensitive detector used for quantification of polymers in solution. An inline-coupled ICP-MS possessing low detection limits and high detection speed provides information on the chemical composition of the particles. The transient recording of many mass traces should make it possible to distinguish between the organic and inorganic nature of the particles. The applied coupled measuring system is integrated into the chemical analysis laboratory of the F.A. Finger Institute of building materials and is operated by the Chair of Building Chemistry and Polymer Materials (Prof. Osburg) as well as the Chair of Construction Material Science (Prof. Ludwig).