Finding Order in Chaos: Vibrational Spectroscopy Study of Oriented Soft Materials

软材料的性质和性能取决于它们的化学性质和分子结构：分子在材料中的排列方式。分子的取向是材料结构的一个重要方面。它在高性能纤维、延长食品保质期的薄膜、电视和平板屏幕等方面发挥着重要作用。我们的团队专门研究取向：我们开发了新的振动光谱技术来更好地分析取向，并在其他混乱(无定形和无序)材料中创建取向以改善其性能。这项研究的目标是与我们现有的定向材料计划相一致的三个具体目标。首先，我们想要对含有偶氮苯(Azo)化学单元的材料的“光致伸缩”有一个基本的了解。在这个有趣的现象中，偏振光的照射诱导了偶氮化合物的分子尺度的异构化，导致了中等尺度的取向，最终导致了大规模的运动。我们将应用振动光谱学和其他工具来更好地理解高度争论的光致不稳定性的机制。第二个目标是优化偶氮材料的分子设计，以实现高效的光机械应用，将光能转化为运动或功。其中，我们将使用时间分辨光谱方法(在我们实验室开发)来研究玻璃化转变温度、偶氮化合物的体积、其异构化效率等对光诱导取向和运动的作用。最后，我们将开发新的振动光谱学方法，以避开现有技术测量取向的限制。我们将把它们应用于通过静电纺丝制备的纳米纤维，这项技术具有很好的应用前景，但由于我们对纳米纤维性能的控制不力，其广泛使用受到了限制。我们的研究是创新的，由于我们的特殊专业知识和最先进的基础设施，它无法在世界其他地方进行。它将在三个层面产生重大影响。首先，它将有助于在蓬勃发展的材料科学领域培养20名学生。我们以前的学生现在活跃在加拿大和国外的研究和工业领域。其次，我们将对取向在非晶态材料中的作用以及在无定形材料中的光致移动性和质量输运的激发现象给予新的认识。这些知识将有助于优化偏序软材料的性能。我们的新光谱技术也应该被世界各地的其他研究人员采用。最后，我们将立即产生实际影响，这要归功于我们与工业和军事合作伙伴的持续合作，这些合作伙伴寻求我们在定向和光谱学方面的专业知识，以改善它们在现实世界的应用。

The properties and performance of soft materials depend on their chemical nature and on their molecular structure: how the molecules are arranged within the material. The orientation of molecules is a critical aspect of materials structure. It plays a large role in high-performance fibers, in films that extend food shelf-life, in televisions and flat screens, etc. Our group specializes in the study of orientation: we develop new techniques of vibrational spectroscopy to better analyze orientation and we create orientation in otherwise chaotic (amorphous and disordered) materials to improve their properties. This research targets three specific objectives in line with our existing program on oriented materials. First, we want to gain a fundamental understanding of "photomobility" in materials containing azobenzene (azo) chemical units. In this intriguing phenomenon, irradiation with polarized light induces a molecular-scale isomerization of the azo that leads to an intermediate scale orientation and finally to large-scale motion. We will apply vibrational spectroscopy and other tools to better understand the highly debated mechanism of photomobility. The second objective is to optimize the molecular design of azomaterials for efficient "photomechanical" applications where light energy is converted into motion or work. We will use, among others, a time-resolved spectroscopy method (developed in our lab) to study the role of the glass transition temperature, the bulkiness of the azo, its isomerization efficiency, etc., on light-induced orientation and motion. Finally, we will develop new methods of vibrational spectroscopy that will sidestep limitations of the existing techniques to measure orientation. We will apply them to nanofibers prepared by electrospinning, a technique with highly promising application prospects but whose widespread use is limited by our poor control of the properties of nanofibers. Our research is innovative and, thanks to our specific expertise and state-of-the-art infrastructure, it could not be conducted elsewhere in the world. It will have significant impact at three levels. First, it will contribute to the training of 20 students in the thriving field of materials science. Our previous students are now active in research and industry in Canada and abroad. Second, we will cast new light on the role of orientation in amorphous materials and on the exciting phenomena of photomobility and mass transport in azomaterials. This knowledge will help optimize the performance of partially ordered soft materials. Our new spectroscopy techniques should also be adopted by other researchers worldwide. Finally, we will have an immediate practical impact thanks to our ongoing collaborations with industrial and military partners who seek our expertise in orientation and spectroscopy to improve their real-world applications.