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Abstract
Two series of semi‐fluorinated chiral liquid crystals, 2F(m = 8–12) and 3F(m = 8–12), with monofluoro‐substitution at the 2‐ and 3‐positions of the first phenyl ring near the chiral chain, respectively, have been synthesized and characterized. The mesomorphic properties were analyzed by differential scanning calorimetry, polarizing optical microscopy and electric‐optical measurements. It was found that in the series 2F(m = 8–12) the two materials 2F(m = 8, 10) exhibit broad temperature ranges for the antiferroelectric phase with the phase sequence
. In the series 3F(m = 8–12), the three materials 3F(8–10) display the
transition, accompanied by a higher order ferroelectric SmX* (SmI* or SmF*) phase. The remaining materials exhibit SmA* and SmC* phases. The switching current, spontaneous polarization, title angle, dielectric constant and electro‐optical response for the materials in the SmC*,
and SmX* phases were measured. The effect of the position of the fluoro substituent and the influence of the alkyl chain length on mesomorphic behaviour are discussed.
Acknowledgment
The authors are grateful for the financial support of the National Science Council of Taiwan, ROC (NSC 93‐2216‐E‐036‐021).