With water droplets as sacrificed templates at a particular humidity, micro-porous solid thin films were successfully fabricated by self-assembly using an amphiphilic block polymer, polystyrene-b-polyacrylic acid (PS-b-PAA). Interface interactions between the micro-porous thin film and a cationic surfactant, cetyltrimethylammonium bromide (GAB), are investigated by in-situ AFM in aqueous solutions. An interesting phenomenon was observed in water and GAB solution, which the dimensions of the micropores are remarkably larger than the dimensions of those in air. The solid thin films exhibit different surface morphologies in response to stimulus by different concentrations of GAB. These observations were explained by positing that the PAA chains in the micropores stretch and contract with interface interactions between PM and GAB. A promising electrochemical application of this film is suggested. This study is aimed at strategies for the functionalization of stimulus-responsive micro-porous solid thin films with tunable surface morphologies, and exploring new smart materials. (C) 2010 Elsevier Inc. All rights reserved.