| dc.description.abstract | Recently, the electro-optical characteristics of blue phase liquid crystals (BP-LCs), such as the temperature range, stabilization as applying voltages, etc, have been paid much attention significantly. Moreover, the temperature range of BP-LCs is definitely narrow. It is clear that the extension of temperature range is one of the key points in BP-LCs field. Polymer-stabilized blue phase is the most commonly used method to extend the temperature range of BP-LCs. In this thesis, the electro-optical properties of chiral polymer-doped BP-LCs, as well as the comparisons between achiral and chiral polymers, are reported.
According to the experimental results, the polymerized chiral polymer onto the substrates can be used to extend the temperature range of BP-LCs significantly. To elucidate the mechanism for extending the temperature range of BP-LCs, several factors for the processes of photo-polymerization are considered. They includes (1) concentration of chiral dopant and chiral polymer; (2) LC phase (cholesteric, blue, and isotropic phases) during photo-polymerization; (3) curing duration; (4) cell gap, and others. It is demonstrated that the temperature range of BP-LCs can be extended to 30oC by polymerizing chiral polymer (6 wt%) polymerization in isotropic phase. Refer to some references; the extension of temperature range of BP-LCs via polymer stabilization can only be achieved by polymerizing achiral polymer in LC blue phase. Thus the proposed method (chiral polymer) is much easier than the conventional one (achiral polymer) to extend the temperature range of BP-LCs. Additionally, the electro-optical properties of chiral polymer-stabilized BP-LCs are as good as those of polymer-stabilized BP-LCs.
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