具含氟單體前驅物之高分子穩固藍相液晶的光電與介電性質

Abstract

本研究主要探討摻含氟單體之高分子穩固藍相液晶在水平電場驅動下之光電特性。我們在既有的高分子混合物（RM257 + TMPTA）中添加含氟單體，在固定RM257與TMPTA之比例為1:1以及總濃度為10 wt%的條件下，以含氟單體濃度為變數進行研究。由電壓穿透率量測結果得知，隨著含氟單體的濃度由0 wt%增加至2.7 wt%，高分子穩固藍相液晶之驅動電壓將有效地由46下降至32 V。此外，含氟單體的摻雜可增加高分子網絡的強度，進而降低因電壓驅動後所造成的相位遲滯。 為了進一步了解含氟單體影響高分子穩固藍相液晶光電特性之原因，我們以介電頻譜術分析樣品在高分子聚合後之離子行為。透過數據擬合我們發現，具有含氟單體之高分子穩固藍相液晶，其離子濃度隨著含氟單體濃度的增加而減少，因此我們認為含氟單體在完成聚合後，可有效吸咐藍相液晶中之離子雜質，進而抑制電雙層的形成並降低驅動電壓。

This study focuses on the electro-optical properties of in plane switching (IPS) mode polymer-stabilized blue phase liquid crystals (PS-BPLCs) impregnated with fluorine-containing monomer precursors. The monomer mixture used contains three materials—RM257, TMPTA, and fluorine-containing monomer precursors. The weight ratio between RM257 and TMPTA is 1:1 and the concentration of the monomer mixture with respect to the BPLC is fixed to 10 wt%. Experimental results based on the voltage-dependent transmission curves indicate that the operating voltage of PS-BPLCs can effectively be reduced from 46 to 32 V when increasing the concentration of fluorine-containing monomer precursors from 0 to 2.7 wt%. Moreover, impregnating the fluorine-containing monomer precursor into PS-BPLCs enhances the strength of polymer networks and thus, reducing the residual phase retardation, caused by electric field induced helical deformation. Furthermore, in order to realize the influence of fluorine-containing monomer precursors on the electro-optical properties of PS-BPLCs, the ionic behaviors of samples after photopolymerizations are investigated by means of dielectric spectroscopy. By fitting experimental results into appreciated formula, it is found that the ionic concentration of the PS-BPLC gradually gets decreased with increasing dopant concentration of fluorine-containing monomer precursors. This implies the ion-trapping ability of the fluorine-containing polymers so as to repress the strength of the electrode double layer and reduce the operating voltage of the PS-BPLCs.