Stacks of correlated polymer lamellar crystals as platform for functional assemblies

聚合物片状晶体可以被认为是具有可调厚度和(功能)表面性质的准二维纳米薄片家族的一部分。除了单层晶体外，溶液或熔体还可以形成具有独特取向的多层聚合物晶体的相关堆栈。人们普遍认为，在基片的无定形褶皱表面上形成新的结晶层需要一个成核过程。然而，负责堆叠形成的机制以及堆叠的层如何相互连接尚不清楚。在这项联合提案中，我们的目标是从均聚物和嵌段共聚物中生产大量相关的聚合物片层晶体。通过系统地改变高分子链的特征参数和结晶条件，可以调节层状核和界面层的厚度、层状层数和连接链面密度。我们将系统而详细地研究自诱导成核对褶皱表面的影响。对于相关片层堆叠的形成，将建立一个考虑形核、生长和扩散竞争的模型。此外，我们将使用层叠的相关聚合物片状晶体作为功能各向异性组件的平台，以产生具有单晶特征的复合材料。例如，我们将合成末端官能化的高分子链(例如，使用四苯基乙烯)，当末端基团以高面密度聚集时会发光，导致聚集诱导发射。这种末端官能化聚合物结晶后，官能团被限制在晶片之间的无定形夹层中。我们还将尝试在无定形夹层中加入量子点或小染料分子。我们将详细研究堆积层状晶体的荧光行为(取向和偏振相关性)。此外，锂盐将被插入到非晶态中间层中，并将测量其电(传输)性能。我们期望联合项目的成果不仅将加深我们对聚合物晶体中自诱导成核导致相关聚合物片层晶体(高)堆栈形成的中心机制的理解，而且还将为基于二维聚合物片层晶体相关堆栈设计功能材料提供新的概念。

Polymer lamellar crystals can be considered as part of the family of quasi-two-dimensional nano-sheets with tunable thickness and (functional) surface properties. Besides single-layer crystals, correlated stacks of multi-lamellar polymer crystals with unique orientation can be generated from solution or melt. It is generally accepted that the formation of new crystalline layers on top of the amorphous fold surface of a basal lamella requires a nucleation process. However, the mechanism responsible for stack formation and how the stacked layers are mutually connected is not yet clear. In this joint proposal, we aim to produce stacks of correlated polymer lamellar crystals, both from homopolymers and block copolymers. The thickness of the lamellar core and the interfacial layer, the number of lamellar layers and the areal density of connecting tie chains in the stacks will be tuned via systematic variation of characteristic polymer chain parameters and crystallization conditions. The effect of self-induced nucleation on the fold surface will be examined methodically and in detail. For the formation of stacks of correlated lamellae, a model accounting for the competition of nucleation, growth and diffusion will be developed. Furthermore, we will employ stacks of correlated polymer lamellar crystals as platform for functional anisotropic assemblies yielding composite materials exhibiting features of single crystals. For instance, we will synthesize end-functionalized polymer chains (e.g., using tetraphenylethylene) which emit light when the end-groups aggregate at high areal densities, leading to aggregation-induced emission. After crystallization of such end-functionalized polymers, the functional groups are confined within amorphous interlayers between crystalline lamellae. We will also attempt to incorporate quantum dots or small dyes molecules within the amorphous interlayers. The fluorescence behavior (orientation and polarization dependence) of the stacked lamellar crystals will be investigated in detail. In addition, lithium salts will be inserted into amorphous interlayers and the electric (transport) properties will be measured. We expect that the outcome of the joint project will not only deepen our understanding of the central mechanism of self-induced nucleation in polymer crystals leading to the formation of (high) stacks of correlated polymer lamellar crystals, but also provide new concepts for designing functional materials based on correlated stacks of two-dimensional polymer lamellar crystals.