Molecular mass determination in the liquid crystalline state - lyotropic cholesteric phase of a cellulose derivative

Lyotropic cholesteric phases of cellulose derivative/solvent systems exhibit a reflection wavelength or supermolecular helicoidal pitch dependency on molecular mass besides the well known variation of the pitch by temperature and concentration. This observation allows a molecular mass determination by spectroscopic means (UV/VIS-, ORD-, CD-spectra) or by an evaluation of the colours seen in a polarizing microscope or by a direct measurement of the pitch with the Cano-Grandjean technique.