ENGINEERING RESEARCH EQUIPMENT: Differential Scanning Calorimeter for Liquid Crystal Research

CTS-9411604 Chen 请求提供设备资金，用于采购Perkin Elmer DSC-7型差示扫描量热仪，以帮助启动一个低摩尔质量玻璃形成液晶项目。 应该注意的是，单晶和液晶都在光学和激光系统中发现了许多潜在的应用。 尽管单晶难以加工，但液晶器件缺乏环境耐久性。 为了克服这些问题，近年来已经开发了能够玻璃化的液晶聚合物。 然而，聚合物材料的高粘性性质已经提出了器件均匀性至关重要的加工问题。 因此，理想的材料除了具有必要的光学特性外，还应具有低熔体粘度。 迄今为止，很少有低摩尔质量的液晶能够玻璃化，玻璃化转变温度高于环境温度。 此外，从化学结构的角度对玻璃形成液晶的理解很少。 有人提出，两个看似相反的结构特征，介晶核心和体积排除部分，通过一个灵活的间隔化学键合到彼此。 为了在介晶核和体积排除部分的类型、每体积排除部分的介晶核的数量和柔性间隔基长度之间取得微妙的平衡，是在单个分子实体中实现液晶介晶性和玻璃形成的关键。 代表性的结构已被提出的合成和表征，分子模拟将随后进行提供新的见解玻璃形成和液晶介晶的有机分子。 用于眼镜和光学系统应用的高双折射聚合物、水凝胶和脂环族聚合物的其他正在进行的项目也将受益于即将收购的DSC系统。 ***

CTS-9411604 Chen Equipment funds are requested for the procurement of a Perkin Elmer DSC-7 differential scanning calorimeter to help initiate a project on low molar mass glass-forming liquid crystals. It should be noted that both single crystals and liquid crystals have found numerous potential applications in optical and laser systems. Whereas single crystals are difficult to process, liquid crystal devices lack environmental durability. To overcome these problems, liquid crystalline polymers capable of vitrificaton have been explored in recent years. However, the highly viscous nature of polymeric materials has presented a processing problem where device uniformity is critical. Hence, ideal materials should possess low melt viscosity besides requisite optical characteristics. Few low molar mass liquid crystals capable of vitrification with glass transition temperature above the ambient have been reported to date. Furthermore, there is little understanding of glass-forming liquid crystals from the perspective of chemical structure. It is proposed that two seemingly opposing structural features, a mesogenic core and a volume-excluding moiety, be chemically bonded to each other via a flexible spacer. To strike a subtle balance between the types of mesogenic core and volume-excluding moiety, the number of mesogenic cores per volume excluding moiety, and the flexible spacer length is the key to accomplishing liquid crystal mesomorphism and glass formation in a single molecular entity. Representative structures have been proposed for synthesis and characterization, and molecular simulation will subsequently be performed to furnish new insights into glass formation and liquid crystal mesomorphism by organic molecules. Other on-going projects on high birefringence nematic polymers, hydrogels, and cycloaliphatic polymers for eye wear and optical systems applications will also benefit from the DSC system to be acquired. ***