Non-uniformities in polymer/liquid crystal mixtures
II. Nematic nucleationA. Matsuyama1, R.M.L. Evans2 and M.E. Cates3
1 Department of Chemistry for Materials, Faculty of Engineering, Mie University, Tsu Mie 514-8507, Japan
2 Department of Physics and Astronomy, The University of Leeds, Leeds LS2 9JT, UK
3 Department of Physics and Astronomy, The University of Edinburgh, Edinburgh EH9 3JZ, UK
(Received 9 August 2002 / Published online: 22 November 2002)
We theoretically model the nucleation of nematic droplets during phase ordering in mixtures of a flexible polymer and a low-molecular-weight liquid crystal. By appealing to classical nucleation theory (CNT), we calculate the energy barrier to nucleation and the size of a critical nucleus. We study the influence of a metastable intermediate phase on the nucleation of the nematic. Below a triple point in the phase diagram, there are two distinct mechanisms for the formation of a nematic nucleus: 1) direct nucleation from the isotropic phase and 2) nucleation via a precursor metastable isotropic phase. We calculate the crossover concentration as a function of temperature, delineating the regions of the phase diagram in which each mechanism prevails. In the latter case, the presence of a hidden metastable isotropic-isotropic binodal may either promote or delay the nucleation of a nematic phase.
61.30.-v - Liquid crystals.
61.30.St - Lyotropic phases.
64.90.+b - Other topics in equations of state, phase equilibria, and phase transitions.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2002