Phase behavior of polymer blends with reversible crosslinks—A self-consistent field theory study

An extended version of self-consistent field (SCF) theory that was recently introduced by the authors [Li et al., J. Chem. Phys.137, 024906, (2012)] is used to study the phase behavior of a polymer blend with reversible crosslinks. The system consists of symmetric AB diblock copolymers and homopolymers of type A and B. We consider reversible crosslinks that can form between the diblock copolymers with a crosslink strength z and crosslink weights ωA and ωB for monomers of type A and B, respectively. Crosslinks between homopolymers are disabled. We present a phase diagram as a function of the A fraction of homopolymers \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\phi _{{\alpha }}^{{\rm{rel}}}$$\end{document}, the crosslink strength z, and the crosslink asymmetry ∆ω = ωA − ωB. A hexagonal phase is found for suitably large \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\phi _{{\alpha }}^{{\rm{rel}}}$$\end{document}, and suitably small z and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left| {\Delta {{\omega }}} \right|$$\end{document}. Otherwise the system forms a lamellar phase. A deeper insight into the phase behavior is gained from analyzing the free energy contributions in the hexagonal and the lamellar phase with the help of the capabilities of the extended SCF theory developed by us.