Phase diagrams of thermally stable, polymer-dispersed liquid crystals: Exploring the impact of chain length and chemical structure

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• 作者：Keon-Soo Jang and LaShanda T.J. Korley
• 刊名：Polymer Engineering & Science
• 出版年：2016
• 出版时间：April 2016
• 年：2016
• 卷：56
• 期：4
• 页码：388-393
• 全文大小：438K
• ISSN：1548-2634

文摘

Polymer-dispersed liquid crystals (PDLCs) have garnered significant interest and motivated the investigation of the phase behavior of thermally stable smectic liquid crystals (LCs) via thermally induced phase separation (TIPS). In this study, we examined a series of two, biphenyl-based smectic LCs suitable for high temperature polymer blend processing. Phase diagrams for LC/polystyrene (PS) blends at various compositions (0–60 wt%) were constructed. Less than 15 wt% of 8B8 (1,1′-biphenyl-4,4′-diyl dioctanoate) LC in PS led to good polymer miscibility, while phase separation was induced at concentrations higher than 15 wt%. The LC concentration at saturation decreased with increasing aliphatic chain length. We also investigated the chain length (C6-C16) effect on the PS glass transition temperature (T_g) at the LC saturation point. The T_g increased with increasing chain length due to reduced plasticization. We further examined the role of chemical structure (relatively less polar ether vs. more polar ester) on the phase diagram regions and the T_g of the nonpolar PS matrix, respectively. It is anticipated that these LC/PS phase diagrams will benefit elevated temperature processing for TIPS by highlighting the role of LC chemical structure and chain length on blend morphology. POLYM. ENG. SCI., 56:388–393, 2016.