This project has two objectives. First is to investigate the influence of lateral confinement on phase separation kinetics and dynamics of polymer blend thin films. Second is to evaluate theblend morphologies under various aspect ratios of strip width to film thickness. The blend thin film is laterally confined by either micro-molding or micro-contact printing(mCP). The polymer blend used for the study contains a 50/50 by mass of poly(methyl methacrylate) (PMMA) and poly(styrene-ran-acrylonitrile) (SAN). This blend exhibits a lower critical solution temperature (LCST) with a critical temperature of 160°C. The samples are annealed inside a vacuum oven at 200°C. The surface topography as well as the interface between the PMMA-rich and SAN-rich phases are evaluated by Atomic Force Microscopy (AFM) and confocal microscopy. The samples are examined before and after the removal of the PMMA-rich phase.

We have studied the dynamics of phase separation under lateral confinement (Zhang Newby, submitted to Macromolecules). One distinguishing observation for laterally confined film compared to the semi-infinite film case is the formation of the SAN-rich core encapsulated by the PMMA-rich shell. This core/shell morphology is only observed with the strips having a strip width to film thickness aspect ratio less than 20. Currently, we are investigating how the final phase morphology depends on various aspect ratios.

Post-doc: Bi-min Zhang Newby