Surface Morphology Diagram for Thin Cylinder-Forming Block Copolymer Films
Xiaohua Zhang, Sangcheol Kim, Brian C. Berry, Ronald L. Jones, Jack F. Douglas, and Alamgir Karim
We investigate the effect of annealing temperature and film thickness on the surface morphology of thin films of cylinder forming block copolymers (BCP). A sharp transition from a perpendicular to parallel cylinder orientation with respect to the substrate is observed upon increasing the BCP (PS-b-PMMA) film thickness hf when the substrate interaction is highly selective for one of the blocks (PMMA), while the polymer-air interface has a nearly unselective interaction with both blocks. Surface morphology transitions with increasing hf are observed in these model ‘frustrated’ interaction films: (a) first a transition from cylinders oriented perpendicularly to the substrate to a mixed or ‘hybrid’ state where the two orientations coexist (b) the hybrid state then transforms to cylinders oriented perpendicularly to the polymer air interface for larger hf . The critical values of hf defining these surface morphological transitions depend on annealing temperature and we construct a surface morphology diagram as a function of hf and T. We interpret the transition lines in the surface morphology diagram in terms of the variation of the interblock interaction with T and hf.
Author information:
Xiaohua Zhang
Mentor: Alamgir Karim
Polymers Division
Bldg 224 Room B204
MS 8541
x 5189 (ph)
x 3928 (fax)
not a member of Sigma Xi
Poster Category: Materials