Structural reorganizations in thin block copolymer films during vapor treatment

Prof. Dr. Christine M. Papadakis

Block copolymer thin films are attractive candidates for the fabrication of sensors or of high-density data storage devices. At this, solvent vapor post-treatment has emerged as a routine method to anneal defects in block copolymer thin films appearing during the preparation by spin-coating. This way, long-range ordered mesoscopic structures are obtained.

Using real-time, in-situ grazing-incidence small-angle X-ray scattering (GISAXS) at synchrotron sources, we have found that the processes encountered during solvent vapor treatment of block copolymer thin films are complex. We have investigated the swelling and the rearrangement of the lamellae in thin films of lamellar poly(styrene-b-butadiene) diblock copolymers during treatment with saturated vapors of selective and non-selective solvents. Instabilities and transient states are encountered which we attribute to the interplay between the increasing polymer mobility, the decreasing interfacial tension between the two blocks and the changing molecular conformation upon uptake of solvent.