Kinetics of the Ordered Phase Growth across the Isotropic-Nematic Phase Transition in Liquid Crystal Azomethine Polymers during Cooling |
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Authors: | Sergei Kostromin Sergei Bronnikov Elena Perju Vasile Cozan |
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Affiliation: | 1. Russian Academy of Science , Institute of Macromolecular Compounds , Sankt Petersburg , Russian Federation;2. Romanian Academy , “Petru Poni” Institute of Macromolecular Chemistry , Ia?i , Romania |
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Abstract: | Main-chain azomethine liquid crystal (LC) polymers varying in spacer length were studied using differential scanning calorimetry and polarizing optical microscopy. The nematic droplets appearing across the isotropic-nematic phase transition during cooling the polymer melt were treated statistically and their size distributions were described with equation based on the principles of irreversible thermodynamics. Kinetics of the ordered phase growth was described analytically with the universal law for cluster growth. Analysis of the mean LC droplet diameter as a function of time allowed recognition of two regimes of the ordered phase growth: i) nucleation and fast LC droplet growth and ii) consequent cluster coarsening. The length of the spacer in the polymer chain was shown to have an influence on the duration of the LC droplet growth regimes. |
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Keywords: | azomethine liquid crystal polymers isotropic-nematic phase transitions polarizing optical microscopy differential scanning calorimetry model of reversible aggregation ordered phase growth |
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