OPTICAL STUDIES OF SUPRAMOLECULAR TUBULAR STRUCTURES GENERATED BY TAPER-SHAPED SIDE-GROUPS IN THE COLUMNAR HEXAGONAL PHASE

Birefringence measurements in the columnar hexagonal phase (phi(h)) an d turbidity measurements in the high temperature isotropic phase (I) h ave been performed on a polymethacrylate (12-AG-4EO-PMA) having taper- shaped side groups: the same measurements were also performed on a sel f-assembling monomeric precursor (12-AG-4EO-OH). We found that the opt ical retardation increases strongly with decreasing temperature in the phi(h)) phase, whereas the turbidity shows no systematic pretransitio nal behavior on approaching the phi(h)-I phase transition temperature T(phih1) from above. Additionally, we found a large bisphasic region a round T(phih1) for mixtures of the monomer and polymer. These results are discussed in terms of the turbidity being dominated by columnar, r ather than orientational, fluctuations.