Development of a 2D-FTIR/Dielectric Spectrometer for Materials Research

这项拨款将有助于开发一种新的聚合物表征仪器，该仪器将结合介电弛豫和二维（2D）红外光谱测量。多年来，介质弛豫测量一直被用作聚合物链动力学的探针，通过检测由各种耦合或局部运动引起的跃迁和弛豫。红外光谱提供了分子水平结构的探测，在某些系统中，还提供了分子间相互作用的探测。显然，一种技术（或者更准确地说，一种混合技术）可以测量各种跃迁和弛豫的温度和频率范围，同时探测所涉及的官能团及其运动耦合的程度，将是一种极其强大的分析工具。本质上，我们将使用介电光谱仪提供振荡电场来调制样品的偶极子。这种调制可以用红外光谱来探测。应用互相关分析的标准方法，得到的同相和非相信号可以用来构建二维图，其中，除其他外，允许识别其运动耦合的官能团。通过改变应用于样品的振荡频率及其温度，可以研究聚合物（和其他）材料中发生的弛豫和转变的分子基础，为结构和动力学提供了新的强大探针。新仪器最初将应用于我们研究小组面临的一系列问题，包括识别聚合物共混物中特定相互作用中涉及的官能团，这种混合物中官能团和链段的动力学，可结晶混相共混物中发生的弛豫现象，聚合物液晶和聚合物分散液晶中的弛豫，等等。当聚合物链受到外力，如拉伸或其他类型的机械变形时，链需要时间来调整或“放松”到新的构象。聚合物中的弛豫过程是复杂的，取决于一些因素，比如样品中单个链的柔韧性，以及不同链相互缠绕的程度。弛豫过程对聚合物的性质及其用途有着深远的影响，从日常生活中的应用到先进设备的结合。因此，了解这种弛豫所涉及的分子机制不仅对理解目前使用的聚合物的行为，而且对设计新应用的材料都很重要。不幸的是，这些信息并不容易获得，因为某些技术可以测量弛豫过程，但无法提供有关分子机制的信息，而其他技术可以探测分子本身，但无法提供有关弛豫的信息。为了解决这个问题，我们建议建立一种新的混合仪器，同时探测分子弛豫（或聚合物动力学）和分子水平结构。介电光谱和红外光谱分别是两种技术将被结合起来，新仪器将被称为2D-FTIR/介电光谱仪。这两种技术都是分析的标准工具，我们的任务是构建一个样品细胞，使它们能够一起工作

0079432PainterThis grant will help develop a new instrument for polymer characterization that will combine dielectric relaxation and two-dimensional (2D) infrared spectroscopic measurements. Dielectric relaxation measurements have been used for many years as a probe of the dynamics of polymer chains, through the detection of the transitions and relaxations that are a result of various types of coupled or local motions. Infrared spectroscopy provides a probe of molecular level structure and, in certain systems, intermolecular interactions. Clearly, a technique (or, more accurately, a hybrid-technique) that can measure the temperature and frequency range of various transitions and relaxations, while simultaneously probing the functional groups involved and the degree to which their motions are coupled, would be an extremely powerful analytical tool. Essentially, we will use a dielectric spectrometer to provide an oscillating electric field to modulate the dipoles of a sample. This modulation can be probed by infrared spectroscopy. Applying standard methods of cross-correlation analysis, the resulting in-phase and out-of-phase signals can be used to construct two dimensional plots, which, amongst other things, allow an identification of the functional groups whose motions are coupled. By varying the oscillatory frequency applied to the sample and its temperature, the molecular basis of the relaxations and transitions that occur in polymer (and other) materials can be investigated, providing a new and powerful probe of structure and dynamics. The new instrument will be initially applied to the range of problems facing our research groups, including the identification of the functional groups involved in specific interactions in polymer blends, the dynamics of functional groups and chain segments in such mixtures, the relaxation phenomena that occur in crystallizable miscible blends, relaxations in polymer liquid crystals and polymer dispersed liquid crystals, and so on.%%%When a polymer chain is subjected to some external force, such as stretching or other types of mechanical deformation, the chains take time to adjust or "relax" to a new conformation. Relaxation processes in polymers are complex and depend upon factors such as the flexibility of the individual chains in a sample and how much different chains are tangled up with one another. Relaxation processes have a profound effect on the properties of polymers and hence their uses, ranging from applications in everyday life to their incorporation into advanced devices. An understanding of the molecular mechanisms involved in such relaxations is therefore important in not only understanding the behaviour of polymers presently in use, but designing materials for new applications. Unfortunately, this information is not easily obtained, as certain techniques can measure relaxation processes, but give no information on the molecular mechanisms involved, while others probe the molecules themselves, but give no information on relaxations.To solve this problem we are proposing to build a new hybrid instrument that will simultaneously probe molecular relaxations (or polymer dynamics) and molecular level structure. Dielectric spectroscopy and infrared spectroscopy, respectively, are the two techniques that will be combined and the new instrument will be called a 2D-FTIR/Dielectric Spectrometer. The two techniques are both standard tools for analysis and our task is to construct a sample cell that will allow these to work together.***