ENGINEERING RESEARCH EQUIPMENT: Differential Scanning Calorimeter for Liquid Crystal Research

CTS-9411604陈设备需要资金用于采购Perkin Elmer DSC-7型差示扫描量热仪，以帮助启动一个关于低摩尔质量玻璃形成液晶的项目。应该指出的是，单晶和液晶在光学和激光系统中都有许多潜在的应用。虽然单晶很难加工，但液晶设备缺乏环境耐用性。为了克服这些问题，近年来人们探索了能够玻璃化的液晶聚合物。然而，聚合物材料的高度粘性带来了一个加工问题，其中器件的一致性至关重要。因此，理想的材料除了具有必要的光学特性外，还应具有较低的熔体粘度。到目前为止，很少有报道能够在玻璃化转变温度高于环境温度的情况下实现玻璃化的低摩尔质量液晶。此外，从化学结构的角度对玻璃形成液晶的认识还很少。有人提出，两个看似对立的结构特征，即介晶核和不含体积的部分，通过柔性间隔物相互化学结合。要在液晶介晶和玻璃形成的单一分子实体中实现液晶的介晶化和玻璃的形成，在介晶核类型和不含体积的部分、单位体积不含部分的介晶核数目和灵活的间隔基团长度之间取得微妙的平衡是关键。具有代表性的结构已被提出用于合成和表征，随后将进行分子模拟，以提供对有机分子的玻璃形成和液晶介晶的新见解。其他正在进行的高双折射向列聚合物、水凝胶和用于眼睛佩戴和光学系统应用的脂环族聚合物的项目也将受益于将获得的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. ***