Polymeric mesophases with positional order in two dimensions are considered in relation to the established liquid crystal phases. It is proposed that the mesophase with hexagonal symmetry observed in polymers as flexible as polyethylene and poly(diethylsiloxane) is columnar liquid crystal. The relationship is discussed with columnar phases in non-discotic low molar compounds and, particularly, with polymers like poly(dialkylsilane)s or alkylated polyglutamates. It is argued that the presently considered hexagonal phases are properly classified as liquid crystalline in spite of the absence of both rigid moieties and amphiphilic character from some of the polymers concerned. Since the phases described here have in the past prompted the introduction of 'condis crystals' as the third class of mesophases, alongside plastic and liquid crystals, some comments are made about the general classification of mesomorphic states.
Посилання на статтю:
Thermotropic hexagonal phases in polymers: common features and classification* / G. Ungar // Polymer. – 1993. – Vol 34. – P. 2050-2059.