Molecular Crystals and Liquid Crystals, Vol.378, 51-58, 2002
Induction of chirality in a cationic surfactant nematic phase by hydroxypropylcellulose
Addition of the water-soluble chiral polymer hydroxypropylcellulose (HPC) to a cationic nematic lyotropic phase induces cholesteric behavior. In this work, thirteen different well-characterized samples of HPC of known molecular weight and polydispersity were added to an N D phase consisting of myristyltrimethylammonium bromide, 1-decanol, ammonium bromide, and water, and the fingerprint texture of the cholesteric phase was utilized to determine the helical twisting powers (HTPs) of the solutes. Samples with molecular weights ranging from 12,000 to 140,000 were soluble in the concentrated surfactant system. Above molecular weight 140,000 phase separation was observed. The HTP of HPC was found to be independent of both molecular weight and molecular weight distribution of the chiral polymer with a value of 11+/-1 (mum wt fraction)(-1) . HTP appears to depend only on the number density of chiral units in the phase and not on the polymer chain length.