聚合物稳定胆甾相液晶网络形变的表征和控制及其对光电性能的影响
发布时间：2018-07-15 08:08
【摘要】：聚合物稳定胆甾相液晶(polymer-stabilized cholesteric texture,PSCT)在一定条件作用下,其网络形貌会发生形变。聚合物网络形变会导致液晶取向,螺距梯度和网络锚定力等发生改变,从而对器件的性能产生重要影响。由于聚合物网络尺度微小,形变程度难以表征。采用扫描电子显微镜(scanning electron microscope,SEM)和共聚焦显微镜(confocal microscope)等手段可以观察网络形貌,但是往往要破坏器件结构,且不能表征网络形变的动态过程。聚合物稳定胆甾相液晶,其动态响应过程源于液晶局部指向矢(local director)的重新排列。这一过程由介电耦合效应(dielectric coupling effect) /自组装效应(self-assembly effect)和聚合物网络形变(polymer network deformation)来主导。使用双指数模型来拟合动态响应的实测数据,能拟合的很好,拟合度达到99%以上。通过对动态响应瞬间上升和下降过程的模拟,聚合物网络形变的程度可以被定量的计算出来。通过调节驱动电场强度,驱动信号频率,环境温度和单体浓度可以控制聚合物网络的形变程度。在一定范围内,降低驱动电场强度、提高驱动信号频率、降低环境温度或增大单体浓度能分别减弱聚合物网络形变的程度。降低聚合物网络形变程度和提高网络形变回复速度能有效地抑制迟滞(hysteresis)效应;在其他条件相同的情况下,更小的网络形变还能缩短撤电响应时间(field-offresponse time)。以上研究结果,为制备PSCT器件和优化其性能提供了积极有益的指导。
[Abstract]:The network morphology of polymer stabilized cholesteric liquid crystal (polymer-stabilized cholesteric) will deform under certain conditions. The deformation of polymer network will lead to the change of liquid crystal orientation, pitch gradient and network anchoring force, which will have an important impact on the performance of the device. Because the scale of polymer network is small, it is difficult to characterize the degree of deformation. Scanning electron microscope (scanning electron) and confocal microscope (confocal microscope) can be used to observe the morphology of the network, but the device structure is often destroyed and the dynamic process of network deformation can not be characterized. The dynamic response of polymer stabilized cholesteric liquid crystal is due to the rearrangement of the local directional vector (local director) of the liquid crystal. The process is dominated by dielectric coupling effect (dielectric coupling effect) / self-assembly effect) and polymer network deformation (polymer network deformation). Using the double exponential model to fit the measured data of dynamic response can fit well, and the fitting degree is over 99%. The degree of deformation of polymer networks can be quantitatively calculated by simulating the transient ascending and descending process of dynamic response. The deformation degree of polymer networks can be controlled by adjusting the driving electric field intensity, driving signal frequency, ambient temperature and monomer concentration. In a certain range, the degree of polymer network deformation can be reduced by decreasing the driving electric field intensity, increasing the driving signal frequency, lowering the ambient temperature or increasing the monomer concentration. Reducing the degree of polymer network deformation and increasing the recovery rate of network deformation can effectively suppress the hysteresis (hysteresis) effect, and the smaller network deformation can also shorten the response time (field-offresponse time).) under the same conditions. These results provide useful guidance for PSCT device fabrication and performance optimization.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O753.2
本文编号：2123420
[Abstract]:The network morphology of polymer stabilized cholesteric liquid crystal (polymer-stabilized cholesteric) will deform under certain conditions. The deformation of polymer network will lead to the change of liquid crystal orientation, pitch gradient and network anchoring force, which will have an important impact on the performance of the device. Because the scale of polymer network is small, it is difficult to characterize the degree of deformation. Scanning electron microscope (scanning electron) and confocal microscope (confocal microscope) can be used to observe the morphology of the network, but the device structure is often destroyed and the dynamic process of network deformation can not be characterized. The dynamic response of polymer stabilized cholesteric liquid crystal is due to the rearrangement of the local directional vector (local director) of the liquid crystal. The process is dominated by dielectric coupling effect (dielectric coupling effect) / self-assembly effect) and polymer network deformation (polymer network deformation). Using the double exponential model to fit the measured data of dynamic response can fit well, and the fitting degree is over 99%. The degree of deformation of polymer networks can be quantitatively calculated by simulating the transient ascending and descending process of dynamic response. The deformation degree of polymer networks can be controlled by adjusting the driving electric field intensity, driving signal frequency, ambient temperature and monomer concentration. In a certain range, the degree of polymer network deformation can be reduced by decreasing the driving electric field intensity, increasing the driving signal frequency, lowering the ambient temperature or increasing the monomer concentration. Reducing the degree of polymer network deformation and increasing the recovery rate of network deformation can effectively suppress the hysteresis (hysteresis) effect, and the smaller network deformation can also shorten the response time (field-offresponse time).) under the same conditions. These results provide useful guidance for PSCT device fabrication and performance optimization.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O753.2
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相关期刊论文 前2条
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2 沈奕,刘丙战,李永忠;胆甾相液晶场致织构变化的偏光显微镜观测[J];现代显示;2005年01期
，本文编号：2123420
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