Synthesis and mesomorphic properties of chiral liquid crystal dimers containing lactate units

A series of symmetrical chiral ferroelectric liquid crystal dimers viz., alkyl bis{(R)-2-[4-(4′-decyloxyphenyl)benzoyloxyphenoxy]propionates}, ABDBP-n (n = 6–10), containing lactate units were synthesized and characterized. The length of the methylene spacer was increased from 6 to 10 in between the two chiral carbons located at the inner side of dimer. All the synthesized dimers exhibited polymorphism by showing N∗, SmA∗, SmC∗ and SmX∗ (unidentified) mesophase sequence. The mesophases and their corresponding transition temperatures were identified by polarized microscopy and differential scanning calorimetric measurements. Electro-optic switching studies of these dimers in SmC∗ phase has exhibited ferroelectric bistable switching characteristics with the maximum spontaneous polarization of about 60.74 nC cm−2. The tilt angles of the SmC∗ phase was also measured to confirm the tilted phase characteristics.