Influence of external pressure and surface energies on the phase evolution of ultrathin blend films under symmetrical confinement

Abstract

Influence of external pressure and surface energies on the phase evolution of ultrathin blend films under symmetrical confinement1 ZHENG ZHANG, ZHEN WANG, YIFU DING, Univ of Colorado - Boulder — We investigate the phase evolution of an ultrathin ( 100 nm) PS/PMMA blend film strongly confined between two parallel rigid plates with identical surface energy. The symmetry was achieved by pressurizing a spun-cast PS/PMMA film on a silicon wafer with a native oxide layer against another silicon wafer under a nanoimprinter. During subsequent annealing without pressurization, preferential wetting of a component (PMMA) occurred on both substrates, leading to phase inversion. The correlation wavelength in the final morphologies was reduced in half, compared with non-capped systems. When annealed while maintaining an external pressure, the predominant preferential substrate wetting of PMMA was prevented completely. 1Acknowledgement is made to NSF and ACS-PRF for financial support.