Experimental and Theoretical Investigation of an Aqueous Two Phase System with a Hyperbranched Polymer

基于水两相体系（ATPS）混相间隙的萃取是浓缩蛋白质的主要方法。这些系统由足够的聚合物、盐组成。本研究项目的基本思想是通过超支化聚酯酰胺与右旋糖酐结合形成atp来扩展材料基础。并与PEG8000和葡聚糖组成的经典ATPS进行了比较。与线性聚合物不同，可以合成具有不同官能团和不同结构的超支化聚合物，这些超支化聚合物会影响其热力学行为和混相间隙。超支化聚合物在流体分离中的另一个优点是与线性聚合物相比粘度低。在两个atp中，l -丝氨酸在两个共存相上的分配被实验研究。相平衡的建模是萃取的基础，它可以通过一个热力学模型来实现，该模型完成了聚合物的结构和官能团。热力学模型是晶格簇理论（LCT）和Wertheim理论的结合。应用所建立的热力学模型，可以通过调整模型参数分别为二元三元子系统来预测l -丝氨酸在两种ATPS相上的分配。作为后续步骤，开发的热力学模型将用于研究两种ATPS的界面现象，如界面张力或跨界面的传质。这些现象的建模将通过将所开发的模型与密度梯度理论（DGT）相结合来进行。DGT给出了非齐次系统的亥姆霍兹能的表达式。因此，有可能计算平衡界面张力，并提供化学势的表达式，从而可以计算传质。除了建模外，还将通过实验确定界面张力和跨界面的传质。在这项研究中，将使用旋转滴法来确定界面张力，并使用尼希池来研究界面上的传质。如果该项目取得成功，除了大大扩展ATPS的物质基础外，还将提供一个描述ATPS的封闭理论，包括相平衡和传质。

Extraction which is based on the miscibility gap of aqueous two phase systems (ATPS) is a principal possibility to concentrate proteins. These systems are composed by adequate polymers, salts. The fundamental idea of this research project was the extension of the material base by the application of hyperbranched polyesteramid in combination with dextran to form an ATPS. The characteristics of this ATPS were compared with a classical ATPS composed of PEG8000 and dextran. In contrast to linear polymers hyperbranched polymers with different functional groups and different architectures which influence the thermodynamic behaviour and the miscibility gap can be synthesized. A further advantage of hyperbranched polymers in fluid separation is the low viscosity compared to linear polymers. In both ATPS the partitioning of L-serin on the two coexisting phases was experimentally investigated. The modeling of the phase equilibria which are the basis of the extraction can be realized by a thermodynamic model which accomplishes for the polymer architecture and the functional groups of the hyperbranched polymer. The thermodynamic model is the Lattice Cluster theory (LCT) combined with the Wertheim Theory. By the application of the developed thermodynamic model it was possible to predict the partitioning of L-serin on the phases of both ATPS by an adjustment of the model parameters to binary respectively ternary subsystems. As a subsequent step, the developed thermodynamic model will be used to investigate interfacial phenomena of both ATPS such as interfacial tension or mass transfer across the interface. The modelling of these phenomena will be conducted by the combination of the developed model with the density gradient theory (DGT). The DGT gives an expression for the Helmholtz Energy of an inhomogeneous system. Therefore, it is possible to calculate the interfacial tension in equilibrium and to provide an expression for the chemical potential which allows calculating the mass transfer. In addition to the modelling the interfacial tension and the mass transfer across the interface will be experimentally determined. For this investigation, the spinning drop method will be used to determine the interfacial tension and a Nitsch-celle will be used to investigate the mass transfer across the interface. If this project is successful, a closed theory for the description of ATPS including phase equilibria and mass transfer would be provided in addition to the considerably extension of the material base of ATPS.