Polyelectrolyte Multilayer-Coated Colloids: Hydration, Internal Properties and Interactions

将研究层状聚电解质复合体中的水化水：将以颗粒为模板，在胶体表面制备交变电荷聚离子逐步自组装形成的多层膜(小组1)。利用这种包覆颗粒的分散体，体积技术可以应用于聚电解质多层膜的研究。聚电解质多层膜形成二维层状网络结构，可与强交联凝胶相媲美。有趣的问题是层状排列对分子尺度上局部性质的影响：局部非均质性是一些重要的宏观性质的关键参数，例如小分子的渗透性。核磁共振自旋弛豫实验提供了包覆胶体分散体中平均水的流动性和结构的信息。2H的自旋弛豫速率将被用在氚水分散体中，以前的实验表明它具有很高的灵敏度(团队1)。可以预料，层中的水存在于不同的位置，因此将进行冻结实验，以研究在略低于冰点的温度下液态水成分的比例和松弛速率。额外的DSC数据可以确认冰点的移动，并可以进一步有助于水中心的分离。此外，多层膜的水合作用可以通过在规定的渗透压下平衡它们来控制(小组2)。平衡距离可以通过结构技术来确定，它是多层膜的内部水化/膨胀以及终止聚合物层的空间排列的函数。将自旋松弛、渗透压平衡和差示扫描量热法等体积法结合起来研究质子交换膜中的水，有望深入了解质子交换膜的水化特性。

The hydration water in layered polyelectrolyte complexes will be investigated: Multilayers formed by stepwise self-assembly of polyions of alternating charge will be prepared on colloidal surfaces, using particles as templates (team 1). Employing dispersions of such coated particles, volume techniques can be applied to the study of polyelectrolyte multilayers. Polyelectrolyte multilayers form a 2-dimensionally stratified network structure, comparable to a strongly crosslinked gel. Interesting questions are the influence of the layered arrangement on local properties on a molecular scale: The local heterogeneity is a key parameter for a number of important macroscopic properties, such as permeability for small molecules. NMR spin relaxation experiments deliver information about the average water mobility and structure in coated colloid dispersions. The spin relaxation rate of 2H in deuterated aqueous dispersions will be employed, where previous experiments showed a high sensitivity (team 1). It can be expected that water in the layers exists in different sites, therefore freezing experiments will be performed to investigate the fraction and relaxation rate of the liquid water component at temperatures just below the freezing point. Additional DSC data can confirm the shift of the freezing point, and can further contribute to a separation of water sites. In addition, the hydration of multilayers can be controlled by equilibrating them at defined osmotic pressures (team 2). The equilibrium distance can be determined by structural techniques, and is a function of the internal hydration/ swelling of the multilayers, as well as of the steric arrangement of the terminating polymer layer. The combination of such volume methods studying water in PEMs, such as spin relaxation, osmotic pressure equilibration and DSC measurements is expected to give insight into details of the hydration properties of PEMs.