Induced circular dichroism of an optically active polyfluorene derivative in phase-separating solutions

When methanol, a nonsolvent, was added to dilute tetrahydrofuran solutions of an optically active polyfluorene derivative, liquid-liquid phase separation occurred, and circular dichroism (CD) was induced at a low temperature. The polymer concentration of the minor separating phase, estimated by light scattering, was very high (similar to 0.4g cm(-3)). The CD induction occurring in that concentrated phase was temperature sensitive. When the phase-separating solution was quenched from 40 to 15 degrees C, the CD increased according to first-order reaction kinetics, and it was a rather slow process (the rate constant was 2.5 x 10(-4)s(-1)). The intermolecular chiral interaction in the concentrated phase may be responsible for the CD induction or non-racemization of this helical polyfluorene derivative in phase-separating solutions. Polymer Journal (2010) 42, 195-200; doi:10.1038/pj.2009.330; published online 23 December 2009