Synthesis and characterization of new ferroelectric liquid crystals containing oligomethylene spacers

Abstract

Two series of ferroelectric liquid crystals containing a phenyl biphenyl carboxylate mesogenic group and oligomethylene spacers (n = 3, 4, 6, 8 ) were synthesized and characterized. The chiral moieties are the (S)-2-methylbutoxycarbonyl and (S)-1-methylheptoxycarbonyl groups. The mesomorphic behaviours of the compounds were characterized using di erential scanning calorimetry and optical polarized microscopy. Spontaneous polarization (Ps) of the liquid crystals was measured by an automated polarization tester over a wide temperature range. The mesomorphic properties are discussed as a function of spacer length and position of the chiral centre. It is found that the phase transition temperature decreases with increasing number of oligomethylene units. The phase behaviours of the LC with (S)-1-methylheptoxycarbonyl are more complex than those with (S)-2-methylbutoxycarbonyl, due to thē exible tail in the former. Moreover, the spontaneous polarization depends mainly on the position of the chiral centre, with Ps < 15 nC cmÕ 2 and Ps = 60~123 nC cmÕ 2 for the series with (S)-2-methylbutoxycarbonyl and (S)-1-methylheptoxycarbonyl groups, respectively.

Synthesis and physical properties of difluoroterphenyl ferroelectric liquid crystal with mixed alkenyloxy‐ester terminal ends

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Synthesis and ferroelectric properties of new chiral liquid crystals derived from (S)‐lactic acid with alkoxyethanols

“…The first increase in P s at lower temperature below T c can be attributed to decreased thermal motion at the lower temperature. After maximum P s is reached, a gradual decrease in temperature resulted in a decreasing P s , which might be due to crystallization [18] or the occurrence of an SmC*-SmX* phase transition. The maximum P s values for the three series of materials were in the range of 28-67.9 nC cm 2 .…”

Synthesis and mesomorphic properties of new organosiloxane chiral calamitic liquid crystals

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