Collaborative Research: Semiconducting Behavior in Silsesquioxane Macromonomers and Polymers

在化学系大分子、超分子和纳米化学项目的支持下，密歇根大学安娜堡分校的Richard Laine教授和John Kieffer教授以及蒙大拿州立大学的Aleks Rebane教授将开发新的硅基聚合物家族。硅油和橡胶是疏水、无色和电绝缘的材料，因此用途广泛。最近，开发了两个含硅聚合物家族，其中含硅构建块与荧光块交替。与大多数已知的硅基材料不同，这些聚合物具有强烈的颜色，明亮的荧光，并且表现为半导体。重要的是，它们仍然保留了传统有机硅的关键特性，如耐水性和阻燃性。半导体聚合物，如有机发光二极管（oled）被发现在平板显示器中，在某些情况下可以用来将阳光转化为电能。因此，对这些新聚合物家族的研究可能会带来意想不到的、潜在的有用特性，为许多日常社会应用带来新的、低成本的、更坚固的材料。本研究项目将有助于培养研究生和本科生拓展对这些材料及其行为的认识。硅氧烷（SQs）是一种独特的、规则对称的3D大分子，类似于单个二氧化硅晶体，非常坚固，一些在600°C下仍保持空气稳定。苯基衍生物也可以通过亲电取代反应选择性官能化。笼形中心与激发态中的附加部分相互作用，提供三维共轭（笼形中心lumo）和半导体行为。有潜力开发具有半导体特性的新聚合物家族，其中硅氧烷桥为光子应用提供潜在价值，例如显示器，混合激光和光伏。这些科学探索途径构成了广泛合作的基础，旨在扩大形成假定的笼型中心发光二极管的笼型架构的数量，详细说明促进此类特性发生所需的替代模式，并优化显示、白光和激光应用的单光子和双光子量子效率。这些目标将通过详细的光物理测量、理论建模和电化学探测来实现，目的是提高对该聚合物家族结构-性能关系的基本理解。有可能为化学家、物理学家、材料科学家和工程师提供重要的新型半导体聚合物。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With support of the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Professors Richard Laine and John Kieffer of the University of Michigan-Ann Arbor, and Professor Aleks Rebane of Montana State University will develop new families of silicone-based polymers. Silicone oils and rubbers are hydrophobic, colorless, and electrically insulating materials and as such find wide uses. Recently, two families of silicon-containing polymers were developed wherein silicon-containing building blocks alternate with fluorescent ones. Unlike most known silicon-based materials, these polymers are intensely colored, brightly fluorescent, and behave as semiconductors. Importantly, they still retain key properties of traditional silicones, such as water and flame resistance. Semiconducting polymers, such as, organic light-emitting diodes (OLEDs) are found in flat panel displays and in some instances can be used to convert sunlight into electricity. Hence the study of these new polymer families could lead to unexpected and potentially useful properties, bringing new, low-cost and more robust materials to many everyday societal applications. This research project will facilitate the training of graduate and undergraduate students to expand knowledge of these materials and their behavior. Silsesquioxanes (SQs) are unique, regularly symmetric 3D macromolecules that resemble single silica crystals in being extremely robust, some remaining air-stable up to 600 °C. The phenyl derivatives of SQs can also be selectively functionalized by using electrophilic substitution reactions. The cage centers interact with appended moieties in the excited state providing 3D conjugation (cage centered LUMOs) and semiconducting behavior. There is potential to develop new families of polymers with semiconducting properties wherein siloxane bridges offer potential value for photonic applications, for example for displays, hybrid lasers and photovoltaics. These avenues of scientific inquiry, which constitute the basis for the broad collaboration, aim at expanding the number of cage architectures that form the presumed cage centered LUMOs, detailing the substitution patterns required to promote onset of such properties, and optimizing one- and two-photon quantum efficiencies for display, white light and laser applications. These goals will be pursued through detailed photophysical measurements, theoretical modeling, and electrochemical probing with the aim of improving fundamental understanding of structure-property relationships in this polymer family. The potential exists to make available important new sets of semiconducting polymers for chemists, physicists and materials scientists and engineers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.