Multiplicity of ‘re-entrant’ cholesteric structures in DNA liquid-crystalline dispersions

Information about properties of liquid-crystalline dispersions of DNA molecules formed as a result of their phase exclusion is systematized. The influence of temperature and osmotic pressure on the structure of these dispersions has been elucidated in the framework of the concept of ‘quasinematic’ layers of orientationally ordered DNA molecules in dispersion particles. A new hexagonal$\rightarrow$‘re-entrant’ cholesteric packing phase transition of DNA molecules discovered by the authors is described, taking into account the generalized Lindemann criterion. The multiplicity of the ‘re-entrant’ phases and their structure are shown to depend on the characteristics of DNA and water-polymer solutions.