Behavior of tethered polyelectrolytes in poor solvents

Using scaling theory and a two-dimensional self-consistent field calculation (SCF), we determine the morphology and phase behavior of charged polymers tethered by one end onto a flat substrate, and immersed in a poor solvent. For degrees of ionization, α, below a critical value, α*, the effects of the poor solvent dominate and the tethered chains collapse into pinned micelles on the planar surface. For values of α>α*, the chains extend to form a laterally uniform layer. This collapsed-to-stretched transformation constitutes a first-order phase transition. The specific routes to this transition are dependent on the relative solvent quality, and are described via the scaling theory. The structure of the layers above and below α* can be visualized through the polymer density profiles, which are obtained from the SCF calculations. The SCF calculations also show agreement with predictions from the scaling analysis.