Synthesis and phase behaviour of a homologous series of polymethacrylate-based side-chain liquid crystal polymers

Abstract

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...

New insights into the transitional behaviour of methyl-6-O-(n-dodecanoyl)-α-D-glucopyranoside using variable temperature FTIR spectroscopy and X-ray diffraction

“…Specifically, the 1472 cm −1 band can be assigned to C-H groups preferentially found in trans conformations. [33,34] The increase in the 1463 cm −1 contribution may then be attributed to a dynamic exchange towards an increased number of gauche configurations of the alkyl chain, indicative of an increase in disorder on melting. In addition, the relative increase of the lower wavenumber contributions (~1454 cm −1 ) may be understood in terms of a greater number of C-H units being involved in stronger intermolecular interactions.…”

Hydrogen bonding and liquid crystallinity of low molar mass and polymeric mesogens containing benzoic acids: a variable temperature Fourier transform infrared spectroscopic study

“…This assignment of a smectic C phase is consistent with the value of the entropy change associated with the clearing transition measured using DSC, DS SmCI /R, of 1.45 which is similar to that normally observed for SCLCPs. [44] Returning to the DSC trace, we can now assign the lower temperature second-order transition to a glass transition and the higher temperature endotherm to a smectic C-isotropic transition. This contradicts the previous phase assignment as a nematic phase but which was made entirely on the basis of the observed optical textures, [7] although molecular weight effects cannot be ruled out, which would also account for the higher clearing temperature observed.…”

Conductive imidazolium side chain liquid crystal polyacrylates prepared from postpolymerization functionalization

“…However, no clear small angle reflection was observed for the smectic phases formed by the imidazolium polyacrylates. Fully interleaved packing of side chains, as the smectic structure of side chain methylpolyacrylates suggested by Cook et al, may account for the XRD patterns. The phase transition temperatures and corresponding enthalpy changes derived from the DSC thermograms are listed in Table .…”