Design and synthesis of dynamic materials

威廉姆斯小组的研究重点是开发工具，使我们能够在纳米、微观和宏观尺度上控制材料的结构。我们正在寻求两个主要的研究途径：1)柱状液晶的研究，它表现出不同寻常的性质，即它们同时是有序的和流动的；2)基于可逆光化学反应的材料设计，这使我们能够利用光来控制材料的性质。我们对液晶的研究集中在一类被称为盘状介原的特殊分子上。这些圆盘状分子堆积成流体柱状结构。近年来，柱状液晶作为光伏（即太阳能电池），led和化学传感器等应用的候选者受到了相当大的关注。我们正试图了解分子水平上的变化是如何影响分子自组织成液晶相的。如果我们要设计可以商业化的材料，这样的理解是必不可少的，对于自我组装过程的基本理解也是至关重要的。我们也在研究在新材料的设计中使用蒽衍生物。这些分子表现出显著的特征，当用近紫外线或可见光照射时，它们形成坚固的二聚体。这些二聚体可以通过将它们暴露在较短波长的光下，转换回原来的蒽分子。因此，使用不同波长的光将材料组合和分离成为可能。这让我们有机会创造出属性可以“即时”编程的材料。我们正在开发新的方法来利用这种反应性，这将对广泛的学科产生影响，包括催化、组合化学、嵌段共聚物、微流体和药物输送。

Research in the Williams group focuses on developing the tools that will enable us to exert control over the structure of materials at the nano-, micro- and macroscale.   We are pursuing two primary avenues of enquiry: 1) the study of columnar liquid crystals, which exhibit the unusual property that they are simultaneously ordered and fluid; 2) the design of materials based on reversible photochemical reactions, which permits us to control the properties of materials using light.    Our studies of liquid crystals focus on a specific class of molecules known as discotic mesogens.  These disc-shaped molecules stack into fluid columnar structures.  Columnar liquid crystals have received considerable attention in recent years as candidates for applications such as photovoltaics (i.e. solar cells), LEDS and chemical sensors.  We are trying to understand how changes at the molecular level impact upon the self-organization of molecules into liquid crystalline phases.  Such an understanding is essential if we are to design materials that can be commercialized, and is also crucial to the fundamental understanding of self-assembly processes.   We are also examing the use of anthracene derivatives in the design of new materials.  These molecules exhibit the notable feature that, when irradiated with near-UV or visible light, they form robust dimers.  These dimers can be converted back into the original anthracene molecules by exposing them to shorter wavelengths of light.  Hence, it is possible to put together and take apart materials using light of different wavelengths.  This gives us the opportunity to create materials who properties can be programmed "on-the-fly".  We are developing new methods in which to exploit this reactivity that will impact upon a broad range of disciplines, including catalysis, combinatorial chemistry, block copolymers, microfluidics and drug delivery.