A comprehensive Langmuir film balance/atomic force microscope study of the surface aggregation behavior of an H-type block copolymer having four branches of polystyrene (PS) blocks (number average molar mass (M-n) = 5000 Da per each branch) and poly(phenylsilsesquioxane) (PPSQ) (M-n = 40,000 Da) has been performed. Temperature dependent surface pressure isotherms and hysteresis experiments were combined with molecules aggregation number per surface micelle, leading to a self-consistent picture of the surface morphology and aggregation phenomena. In spite of the ladder structure of the PPSQ segment, the micelles mostly exist as spherical aggregates because of strong interaction between PS blocks. (C) 2012 Elsevier Ltd. All rights reserved.