Structure and Interfacial Energy Control by Semifluorinated Polymers, as a Mechanistic Tool to Orient Liquid Crystals

半氟化聚合物的结构和界面能量控制作为液晶定向的机械工具

• 批准号: 0203660
• 负责人: Dvora Perahia
• 金额: --
• 依托单位: Clemson University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2007-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0203660&HistoricalAwards=false
• 关键词: Structure; Interfacial; Energy; Control; Semifluorinated

This award seeks to develop the relationship between the molecular structure of a novel class of semifluorinated polymers, and their interfacial structure and energies. Long term it seeks to test the potential of these polymers as support layers to orient liquid crystal thin films. This will be attained using a novel fluoropolymer with a mesogenic group (i.e. liquid crystal molecule), beta-methylstilbene on its backbone bridged by a perfluorocyclobutyl ring (PFCB). The bridging groups are used to control the surface energy and flexibility of the polymer. Atomic Force Microscopy (AFM), polarized optical microscopy, contact angle measurements, and X-ray/neutron scattering and reflectivity will be used. For any liquid crystal based device, the liquid crystal molecules have to be aligned by the surface, however, the have to respond quickly, without any memory effects to an external stimuli. A delicate balance between two opposing factors, surface orientation and weak azimuthal anchoring is requires. The significance of the problem is manifested in the large number of studies, which address the issue. In the last 10 years fluorine has been introduced as a modifier for the surface anchoring. In the present study we propose to utilize the chemical structure of a polymer confined to construct orienting layers. Their surface interactions will depend solely on the nature of the polymer with no further external treatments. The design of the polymer includes incorporating a mesogenic group, or similar chemical backbone, which are expected to serve as a "nucleation site" for inducing ordering, bridged by a group that can modify the surface energy of the polymer to alter the anchoring energy. Standard techniques including differential scanning calorimetry X-ray scattering NMR and polarized optical microscopy will be utilized to characterize the bulk properties of the newly synthesized polymers. Films will then be cast on different supports and will be studied by atomic force Microscopy polarized optical microscopy, contact angle measurements, and X-ray/neutron scattering and reflectivity, to study their structure and surface energies. Following the formation of the energy controlled interfaces; composites with well-characterized liquid crystalline molecules will be formed. The orientation of the LC cast on the polymer layers and its response to electrical stimuli will be studied.The significance of the proposed research lies in the basic understanding of interfacial characteristics of polymers and its correlation with interfacial alignment of liquid crystals leading to far-reaching technological applications, ranging from new fast responding LC devices, to optical wave-guides and new fiber optics.

该奖项旨在开发一类新型半氟化聚合物的分子结构与其界面结构和能量之间的关系。 从长远来看，它试图测试这些聚合物作为支撑层来定向液晶薄膜的潜力。 这将使用具有介晶基团（即液晶分子）的新型含氟聚合物来实现，其主链上的β-甲基芪由全氟环丁基环（PFCB）桥接。 桥连基团用于控制聚合物的表面能和柔性。 将使用原子力显微镜（AFM）、偏振光显微镜、接触角测量以及X射线/中子散射和反射率。 对于任何基于液晶的设备，液晶分子必须通过表面对准，然而，必须快速响应，而对外部刺激没有任何记忆效应。 需要在表面取向和弱方位锚定这两个相反因素之间保持微妙的平衡。 这一问题的重要性体现在针对这一问题的大量研究中。 在过去的10年中，氟已被引入作为表面锚定的改性剂。 在本研究中，我们建议利用聚合物的化学结构限制构建定向层。 它们的表面相互作用将仅取决于聚合物的性质，无需进一步的外部处理。 聚合物的设计包括引入介晶基团或类似的化学主链，其预期充当用于诱导有序化的“成核位点”，通过可以改变聚合物的表面能以改变锚定能的基团桥接。 标准的技术，包括差示扫描量热法，X射线散射，核磁共振和偏光显微镜将被用来表征新合成的聚合物的整体性能。 然后将薄膜浇铸在不同的载体上，并通过原子力显微镜、偏光显微镜、接触角测量、X射线/中子散射和反射率来研究它们的结构和表面能。 随着能量控制界面的形成，将形成具有良好表征的液晶分子的复合材料。 液晶在聚合物层上的取向及其对电刺激的响应将被研究，该研究的意义在于对聚合物界面特性的基本理解及其与液晶界面取向的相关性，从而产生深远的技术应用，从新的快速响应液晶器件到光波导和新的光纤。