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 (B0.4 g cm 3). The CD induction occurring in that concentrated phase was temperature sensitive. When the phase-separating solution was quenched from 40 to 15 1C, the CD increased according to first-order reaction kinetics, and it was a rather slow process (the rate constant was 2.5 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