Investigations on the dynamics of polyelectrolyte multilayers by spinlabeling and EPR spectroscopy

该项目的主题是聚电解质多层膜，它可以通过在各种衬底上使用逐层技术交替吸附聚阴离子和聚阳离子来制备。这是一种通用和广泛适用的技术，能够制造许多不同的定制结构。聚电解质多层膜在表面和膜的靶向修饰方面受到越来越多的关注。各方面，如生长机制、层的内部结构以及动力学等，对实际应用具有重要的意义。虽然结构的许多细节是已知的，但关于多层膜中聚合物的重要动力学的知识要少得多。该项目的目的是对多层膜中聚电解质链段的流动性获得新的见解，并显示这些多层膜的内部结构和动力学与所产生的性质之间的相关性。为了实现这一目标，聚电解质分子被配备有自旋标记，并以定义的方式并入PEM中。EPR谱提供了研究连接到大分子上的自旋标记的旋转扩散的可能性，并获得关于聚合物链段流动性的定量信息，这些信息得到了对较长时间尺度敏感的核磁共振数据的补充。实验研究了所用聚电解质的化学结构、制备PEM的条件、周围介质的参数(离子强度、pH)和聚合物链段在多层膜不同区域的迁移率之间的关系。聚电解质在多层膜中的内部动力学对其作为膜时在多层膜中的传输和通过多层膜的传输有影响。聚合物动力学的温度依赖性和小客体分子的扩散之间的关联导致了对传输机制的深入了解。

Subject of the project are polyelectrolyte multilayers that can be prepared by alternating adsorption of polyanions and polycations using the Layer-by-layer technique on various substrates. It is a general and broadly applicable technique that enables manufacturing numerous different tailored structures. Polyelectrolyte multilayers find increasing attention in the targeted modification of surfaces and membranes. Various aspects, such as the growth mechanism, the internal structure of the layers as well as the dynamics are of fundamental interest for practical applications. While many details of the structures are known, there is much less knowledge for no less important dynamics of polymers in the multilayers. The aim of the project is to gain new insights into the mobility of chain segments of polyelectrolytes in multilayers and to show correlations between the internal structure and dynamics in these multilayers and resulting properties. In order to achieve this goal polyelectrolyte molecules are equipped with spin labels and incorporated in a defined manner in the PEM. The EPR spectroscopy offer the potential to study the rotational diffusion of the spin label linked to the macromolecule and to gain quantitative information about the mobility of polymer segments, which are complemented by NMR data,which are sensitive to longer time scales. The experimental investigations aim at the relationships between the chemical structure of the polyelectrolytes used, the conditions at the preparation of the PEM and the parameters of the surrounding medium (ionic strength, pH) and the mobility of polymer segments in different zones of the multilayer. The internal dynamics of the polyelectrolytes in the multilayers has an influence on the transport in the multilayer and through the multilayer when it is used as a membrane. The correlation of the temperature dependence of the polymer dynamics and the diffusion of small guest molecules results in insights in the mechanism of transport.