高分子分散型液晶之介面極化

Interface polarization in polymer-dispersed liquid crystal

林威廷(Wei-Ting Lin)

中原大學/理學院/物理研究所/碩士(2012年)

https://doi.org/10.6840/cycu201200550

摘要

本論文運用介電頻譜術觀察高分子分散型液晶之極化特性。吾人發現，具高分子與液晶複合結構之高分子分散型液晶，其介電頻譜中多了一極化現象－介面極化，此極化現象出現於中頻率範圍（103 Hz至105 Hz）。為進一步探討高分子分散型液晶中之介面極化特性，本論文分別藉由改變樣品製作參數（如高分子/液晶混合比例與照光聚合條件）以及樣品對外在因素（如電壓和溫度）的依存性，分析介電頻譜的變化。
　　在改變樣品製作參數下，可發現高分子分散型液晶的結構完整與介面極化的貢獻大小有關，高分子分散型液晶結構越完整時，介面極化的現象越明顯。而在外界因素中，隨著溫度的上升，介面極化也會隨之增高，但當溫度到達液晶澄清點溫度時，介面極化的現象將會漸漸消失。在電壓方面，外加電壓需達到高分子分散型液晶之驅動電壓，介面極化才會有明顯的變化。最後高分子分散型液晶放置時間的長短並不影響介面極化的貢獻。本論文有效的將介電頻譜術應用於複合式材料的觀測中，利用介面極化的極化貢獻變化，而了解高分子分散型液晶的各種特性。

關鍵字

高分子分散型液晶 ； 介面極化

並列摘要

In this study, dielectric properties as well as polarization characteristics in a polymer dispersed liquid crystal (PDLC) are investigated based on the dielectric spectroscopy. The dielectric spectrum of PDLC cells indicates that a interface polarization is observed in the frequency regime of 103 Hz to 105 Hz. In this thesis, the concentration of monomer/LC mixture conditions of photo-curing for creating PDLC cells are used as the parameters to clarify the characteristics of interface polarization in the PDLC cell. Furthermore, the effect of external stimulus such as electric field and temperature on the existence of interface polarization in the PDLC cell is disused.
In the case of changing the curing process, one can find the relationship between the interface polarization and PDLC structure. When the PDLC structure is completely formed, the interface polarization is clear. In regard to the discussion to the effect of external stimulus on the formation of interface polarization in the PDLC cell, the interface polarization in the nematic phase of PDLC cells is enhanced with increasing temperature. On the other hand, the interface polarization is clear when the voltage is increased over the critical voltage of the PDLC.
Finally, we confirm that the interface polarization keep permanently even when the PDLC cell is put steadily for a long time. This thesis uses dielectric spectroscopy to investigate the composite material. Based on our experimental results, one can discuss the characteristics of PDLC in terms of the strength of interface polarization.

並列關鍵字

Polymer-Dispersed Liquid Crystals ； Interface Polarization

參考文獻

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