The non-isothermal kinetic analysis of the isotropic-melt to liquid crystalline phase transition of novel liquid crystalline ionogenic copolymers, LCI, the 10-(4-methoxyazobenzene-4'-oxy)decyl methacrylate]-co-2-(acrylamido-2-methyl-1-propanesulfonic acid)s, 10-MeOAzB/AMPS, copolymers, has been performed based on calorimetric experiments at different cooling rates. A classical nonisothermal crystallisation methodology, based on Avrami's equations, was applied and it has shown that the formation of the mesophases from the isotropic state occurred close to the thermodynamic equilibrium and can be described with high accuracy by using different kinetic parameters. The results evidence the presence of several individual processes in the formation of liquid crystalline phases from the melt and a strong dependence of phase transition rates and activation energies with acid contents. In addition, the decrease in the phase transition rate is related to a decrease in orientational entropy and the final inhibition of the liquid crystal behaviour is ascribed to an exponential increase in the activation energy of the phase transition, promoted by strong acid aggregation. An optimum composition of the 10-MeOAzB/AMPS copolymers to achieve the dual characteristics of LCI (ionogenic and liquid crystalline behaviour) requires acid concentrations capable of promoting structure-forming effects on the LC phases and the evolution of phase separated morphologies. I have submitted a manuscript entitled "A kinetic study of the formation of smectic phases in novel liquid crystal ionogens" for consideration for publication in the European PolymerJournal. The manuscript describes the melt-liquid crystal transition of a set of novel liquid crystal side chain copolymers containing sulfonic acid groups having application potential as anisotropic polymer electrolyte membranes. Due to the relevance of the structure-properties relations in these materials, it is important to describe the successive processes involved in the formation of the mesomorphic templates from the isotropic phase. The study of the nonisothermal calorimetric transition carried out in this paper has proved to be useful to describe the forming role of the acid groups on the stabilisation of the liquid crystal phase.The manuscript contains original material which has not been published nor is being considered for publication elsewhere.I look forward to hearing from you in due course. AbstractThe non-isothermal kinetic analysis of the isotropic-melt to liquid crystalline phase transition of novel liquid crystalline ionogenic copolymers, LCI, the 10-(4-methoxyazobenzene-4'-oxy)decyl methacrylate]-co-2-(acrylamido-2-methyl-1-propanesulfonic acid)s, 10-MeOAzB/AMPS, copolymers, has been performed based on calorimetric experiments at different cooling rates. A classical non-isothermal crystallisation methodology, based on Avrami's equations, was applied and it has shown that the formation of the mesophases from the isotropic state occurred close to the thermodynamic...
Three new homologous series of liquid crystal tetramers in which four mesogenic groups are linked via three alkyl spacers have been synthesised and characterised. In each series the length of the outer two spacers, n, is varied from 3 to 12 methylene units while the central spacer is held at 5 methylene units. The three series differ only in the substitution pattern around the inner two mesogenic units. The series in which the inner spacer is attached to the 4-position on both mesogenic groups is referred to as n-p5p-n while n-p5m-n refers to attachment at the 4-position on one group and the 3-position on the other. n-m5m-n refers to attachment at the 3-position on both groups. All the members of the n-p5p-n and n-p5m-n series exhibit nematic behaviour. The nematic-isotropic transition temperatures exhibit a pronounced alternation as the length and parity of the outer spacers are varied but which attenuates as n is increased. By contrast, the odd-even effects shown by the associated entropy changes are not attenuated as n is increased. 4-p5m-4 and 5-p5m-5 also exhibit smectic behaviour. 4-m5m-4 shows a nematic phase and an alternating smectic phase analogous in structure to that observed for certain semi-flexible main chain liquid crystal polymers. The n-m5m-n compounds with n ~6, 8, 9 and 10 also exhibit a nematic phase and a disordered crystalline phase. The trends in the transitional properties of the series are interpreted in terms of average molecular shapes and a model developed to understand the behaviour of liquid crystal dimers.{Basis of a presentation given at Materials Discussion No. 4,[11][12][13][14]
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