Non-uniformities in polymer/liquid crystal mixtures II. Nematic nucleation.
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.
Matsuyama
A
A
Department of Chemistry for Materials, Faculty of Engineering, Mie University, Tsu Mie 514-8507, Japan. matuyama@chem.mie-u.ac.jp
Evans
R M L
RM
Cates
M E
ME