含氟側取代基對於側鏈液晶聚合物液晶性質影響之研究

Abstract

本研究探討側面氟取代基對於所合成聚合物液晶相之影響，總共合成了兩 系列的側鏈聚甲基丙烯酸酯和聚矽氧烷。第一系列具甲基丙烯酸酯含有1 ~ 3個氧乙基間距和2(S)-2-氯-4-甲基戊酸旋光末端基以及雙苯基3-氟苯 甲酸液晶基。所合成之三種聚甲基丙烯酸酯皆只呈現一個互變的層列A型 液晶相。第二系列聚矽氧烷及共聚矽氧烷則含有3~11個亞甲基單位間距 和(S )-2-甲基-1-丁醇旋光末端基以及苯基苯甲酸或苯基3-氟苯甲酸液晶 基。兩個含3個亞甲基間距之聚矽氧烷無液晶相，六個分別含有4，5或6個 亞甲基間距之聚矽氧烷皆呈現互變的層列A型液晶相，而其中兩個含11個 亞甲基間距之聚矽氧烷則有兩個互變的層列型液晶相，至於共聚矽氧烷其 液晶行為與其相對的聚矽氧烷完全相同。研究結果顯示導入側面氟取代基 於液晶基，會降低所有液晶相之熱穩定性，而共聚合物比其相對之聚合物 有較低之相轉移溫度。 The goal of this research is to study the effect of lateral fluoro-substituent on the mesomorphic properties of the prepared polymers. Two series of side-chain liquid crystalline polymethacrylates and polysiloxanes were prepared. The polymethacrylates containing one to tree oligooxethylene units spacers, a (2S)-2-chloro-4-methylvaleric acid chiral end group and a biphenyl 3-fluorobenzoate mesogen. All of the prepared polymethacrylates exhibits only an enantiotropic smectic A phase. The second series of polysiloxanes and copolysiloxanes containing three to eleven methylene unit spacers, a 4-(S)-2- methyl-1-butanol chiral end group and a phenyl benzoate or a phenyl 3-fluorobenzoate mesogen. Both polysiloxanes containing three methylene units in the spacer present no mesophase. Six polysiloxanes containing respectively four, five or six methylene units in the spacers exhibit only an enantiotropic smectic A phase, while both polysiloxanes containing eleven methylene units in the spacer reveal two enantiotropic smectic phases. All of the copolysiloxanes show very similar mesomorphic behavior as their corresponding polysiloxanes. The results demonstrate that incorporation of the lateral fluoro- substituent in the mesogenic side groups depresses the thermal stability of the mesophase formed. The copolymers show much lower thermal transition temperature than their corresponding homopolymers.