Self-assembly of a coil-rod-coil block molecule complexed with LiCF3SO3

Enantiotropic liquid crystalline phases were induced by the complexation of docosyl 4-(4-oxy-4'-biphenylcarbonyloxy)-4'-biphenyl carboxylate, containing poly(ethylene oxide) of twelve ethylene oxide subunits, with 0.25 mol of LiCF₃SO₃ per ethylene oxide unit. The existence of oblique columnar, rectangular columnar (Col_rec), and smectic A (SmA) mesophases of this complex was demonstrated by a combination of polarized optical microscopy and X-ray diffraction. This complex was observed to transform from the rectangular columnar phase to a lamellar phase on heating. The unusual phase transition behaviour in this complex is believed to originate from the mixing entropy of the added LiCF₃SO₃. Also, the Col_rec-SmA phase transition was accompanied by a change of the packing structure from bilayer to monolayer.