Flexible Conductive Polymer Membranes

与大多数人造塑料不同的是，导电聚合物可以导电，因为它们具有特殊的化学结构，称为共轭。一旦掺杂，也就是带电分子的加入，共轭高聚物链中最初定域的电荷就会被动员起来，通过材料携带电流。例子包括聚吡咯、聚噻吩和聚苯胺。然而，也正是由于这种共轭分子结构，导电聚合物大多是刚性、脆性和非柔性的。机械柔性的缺乏极大地限制了它们在膜和储能技术等领域的应用。为了克服这一缺点，导电聚合物通常与其他柔性聚合物复合，以获得机械性能，例如，涂层在纺织品上或在柔性聚合物膜表面。这样的涂层必须非常薄，否则会损害基材的机械性能。涂层也很容易脱层，并经常从基材上脱落。在文献中，还没有关于由未经改性的本征导电聚合物制成的厚的柔性膜的报道。 Pi的团队最近发现了一种简单的合成工艺，可以制备大尺寸厚(高达1 mm)的纳米多孔聚吡咯膜，在室温下以及一直到-196 oC的液氮温度下都具有极好的膜柔韧性。这种聚吡咯膜具有很高的比表面积，良好的导电性，而且非常轻。科学上，这是柔性聚吡咯的首次发现。这种薄膜具有较高的比表面积、导电性和离子活性、轻薄性和低温性能，在储能、电池、防静电和场屏蔽等领域具有巨大的应用潜力。然而，我们仍然不知道这种结构是如何形成的，以及为什么它在-195℃时仍具有如此大的灵活性。 本研究的目的是：1.研究这种膜的形成机制；2.研究膜的结构与性能的关系。3.探索与其他类型导电聚合物制备类似膜的可能性。4.确定这类膜的潜在应用，包括在合成过程中或合成后膜的功能化。 该项目将培养两名高素质的人员，一名具有聚合物化学和聚合物工程背景，从事合成和膜分析工作。另一位有材料力学背景的学生，研究机械性能与纳米结构的关系。

Unlike most manmade plastics that are insulator to electricity, conductive polymers can conduct electricity owning to their specific chemical structure called conjugation. Upon doping, i.e., addition of charged molecules, the originally localized charges in conjugated polymer chains become mobilized to carry electricity through the material. Examples include polypyrrole, polythiophene and polyaniline. However, it is also because of this conjugated molecular structure conductive polymers are mostly rigid, brittle and non-flexible. The lack of mechanical flexibility has greatly limited their applications in areas such as membrane and energy storage technologies. To overcome this drawback conductive polymers are often composed with other flexible polymers to gain mechanical performance, for example, coated on textiles or on flexible polymer membrane surface. Such coating has to be very thin otherwise it will compromise the mechanical property of the substrate. The coating also easily delaminates and often detaches from the substrate. In literature there has been no report on thick flexible membranes made of unmodified intrinsically conductive polymers. PI's group recently discovered a simple synthetic process to prepare large sized thick (up to 1 mm) nanoporous polypyrrole membranes with excellent membrane flexibility at room temperature and all way down to liquid nitrogen temperature that is -196 oC. This polypyrrole membrane has very high surface area, good electrical conductivity, and is extremely light. Scientifically this is the first discovery of flexible polypyrrole. Such membrane may have great potential in wide spectrum of applications such as energy storage, battery, antieletrostatic and field shielding, owing to its high surface area, electrical conductivity and ionic activity, lightness and low temperature performance. However, we still don't know the mechanism about how such structure is formed and why it has such flexibility even at -195 oC. This proposal is aiming at following objectives: 1. To investigate how such membrane is formed; 2. To study the structure-property relationship of the membrane. 3. To investigate the possibility of producing similar membrane with other types of conductive polymers. 4. To identify the potential application of such membranes, including the functionalization of the membranes during or after synthesis. This project will train 2 highly qualified personnel, one with background in polymer chemistry and polymer engineering, to work on synthesis and membrane analysis. Another with background in material mechanics, to study the how the mechanical properties are related with nanostructures.