Synthesis of monodisperse, highly ordered polymer foams via milli- and microfluidic techniques

聚合物泡沫在包装、绝缘或冲击保护等不同领域具有很大的商业价值。根据其应用，聚合物泡沫必须满足特定的要求，这些要求可以通过组成和结构来定制。在提议的项目中，我们想研究结构-性质关系。为了表征泡沫结构，需要确定孔隙大小、孔隙数量、孔隙分布和孔隙连通性等许多细节。然而，传统制造工艺的高度复杂性使得控制材料的结构和性能变得非常困难，甚至是不可能的。即使是允许改变泡沫结构的工艺也不允许制造单分散和高度有序的聚合物泡沫。所有市售泡沫都具有广泛的尺寸分布，这意味着其性能只是各自分布的平均值。最重要的是对结构的精确控制，这将使我们能够定制聚合物泡沫的性能。为了达到这一目标，需要找到新的概念。拟议的项目旨在发展这样一个新概念。重点将放在聚苯乙烯泡沫塑料上，但请记住，长期目标是将这一概念推广到各种聚合物泡沫塑料上。这个概念是基于单分散的聚合，高度有序的液体泡沫和乳液，分别通过毫流体和微流体技术产生。其基本思想是通过易于制作的模板来制造所需的材料。在一种情况下，这将是一个苯乙烯含量很高的水中苯乙烯乳液，我们将通过流体技术进行泡沫。随后的发泡乳液聚合旨在产生其孔径与模板泡沫的气泡大小相对应的聚苯乙烯泡沫。在第二种情况下，我们将生成苯乙烯水乳液，它将直接被聚合。期望聚合物泡沫具有与模板乳液的水滴大小相对应的孔径。在这两种情况下，氧化还原引发剂将用于启动自由基聚合。一旦概念确立，我们将开发具有明确孔径梯度的聚合物泡沫的路线。最后但并非最不重要的是，需要测量所得聚合物泡沫的机械性能。为了量化结构和性能之间的关系，我们将比较(a)不同孔径和连通性的单分散聚合物泡沫，(b)没有和具有孔径梯度的单分散聚合物泡沫，以及(c)具有多分散聚合物泡沫的单分散聚合物。

Polymer foams are of great commercial interest in such diverse fields as packaging, insulation or impact protection. Depending on its application a polymer foam has to meet specific requirements which can be tailored via the composition and the structure. In the proposed project we would like to study structure-property relationships. To characterise the foam structure a number of details such as pore size, number of pores, pore size distribution and pore connectivity need to be determined. However, the high complexity of traditional manufacturing processes makes it very difficult, often even impossible, to control the structure and thus the properties of the material. Even processes which allow changing the structure of the foam do not allow manufacturing monodisperse and highly ordered polymer foams. All commercially available foams have a broad size distribution, which means that the properties are just the mean of the respective distribution. It is above all the precise control of the structure which will enable us to tailor the properties of polymer foams. To reach this goal new concepts need to be found.The proposed project aims at developing such a new concept. The focus will be on polystyrene foams, keeping in mind, however, that the long-term aim is to transfer this concept to a broad variety of polymer foams. The concept is based on the polymerisation of monodisperse, highly ordered liquid foams and emulsions which are generated via milli- and microfluidic techniques, respectively. The basic idea is to manufacture the desired materials via templates which are easy to make. In one case this will be a styrene-in-water emulsion with a high styrene content which we will foam via the fluidic technique. The subsequent polymerisation of the foamed emulsion is intended to lead to a polystyrene foam whose pore size corresponds to the bubble size of the templating foam. In the second case we will generate a water-in-styrene emulsion which will directly be polymerized. The polymer foam is expected to have pore sizes which correspond to the water droplet size of the templating emulsion. In both cases a redox-initiator will be used to start the radical polymerisation. Once the concept is established, we will develop a route towards a polymer foam with a clearly defined pore size gradient. Last but not least, the mechanical properties of the resulting polymer foams need to be measured. In order to quantify the relation between structure and properties we will compare (a) monodisperse polymer foams of different pore sizes and connectivities, (b) monodisperse polymer foams without and with a pore size gradient, and (c) monodisperse with polydisperse polymer foams.