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.