Glassy Phases Formed by Fast Cooling of Mesomorphic Materials

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Abstract
Our studies of the phases formed by rapid cooling of mesogenic materials in the and smectic phases are described. More than 40 mesogens were investigated. In many, but not all of the cases, a glassy phase was formed. This was examined with scanning calorimetry and Raman, IR and FIR spectroscopy. All of these techniques support the conclusion that the pattern of molecular disorder in the mesophase is frozen-in when the glass is formed. The relationship between molecular structure and glass-forming ability is discussed. Factors which lead to a large number of molecular conformers (such as terminal alkyl chains) favor glass formation, whereas absence of such factors and the presence of factors such as permanent dipole moments, which encourage molecular ordering, inhibit glass formation.