Surface analysis of diblock copolymer films by TOF‐SIMS in combination with AFM

Abstract

For block copolymers, the chemical difference between the two blocks will result in a preferential segregation of one of the blocks to the interface, but the phase separation is only on a microscopic scale, forming micro‐domain structures due to the influence of inter‐segment linkages, which restricts the extent to which the phases can separate. In this study, we report the characterization of the morphology from the lower disorder–order transition diblock copolymer, polystyrene‐b‐poly(2‐ethyl hexyl acrylate) (PS‐PEHA) where the PS blocks are perdeuterated, using surface techniques. The molecular surface composition and microscopic morphology for the diblock copolymers were obtained by time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS) and atomic force microscopy (AFM). TOF‐SIMS depth profiles of diblock copolymers showed consistently regular alternative patterns with a constant period that was the same size as the lamellar spacing structure, as determined by AFM images. Structural characterization of dPS‐PEHA thin films by TOF‐SIMS and AFM was also performed for different molecular weights and film thickness. Copyright © 2014 John Wiley & Sons, Ltd.