Structure and Properties of New de Vries SmA∗ Liquid Crystals

Artikel i vetenskaplig tidskrift, 2004

We synthesized a chiral mesogen AC11 and two different siloxanes MSi2-AC11 and DSi3-AC11 derived from it by a hydrosilylation reaction. The effects of varying the molecular architecture were investigated with special attention being devoted to the occurrence of the de Vries SmA* phase. Strong hints that all the three molecules follow the scenario suggested by de Vries were found in the behavior of the susceptibility by studies of their electrooptical response in the SmA* phase. In particular DSi3-AC11 containing two mesogens interconnected by a siloxane spacer presented a critical exponent gamma as high as 1.97, indicating a practically pure de Vries behavior Temperature-dependent X-ray analysis revealed that the three materials underwent a small layer shrinkage at the SmA*-SmC* transition.