Phase separation of ultrathin polymer-blend films on patterned substrates

The phase separation of ultrathin polymer-blend films of polystyrene and polybutadiene on microcontact printed alkanethiol patterns with hydrophobic and hydrophilic end groups $(-{\mathrm{CH}}_3$ and -COOH) is investigated by atomic force microscopy. Simulations suggest that the phase-separation morphology can be controlled through patterns that modulate the polymer-surface interaction, and this concept is verified experimentally. Length scale pattern control is found to be limited to a scale on the order of a few micrometers.