The amphiphilic organoboron block copolymer poly (styreneboronic acid)-block-polystyrene (PSBA-b-PS) has been prepared through a postpolymerization modification route from the silicon-functionalized block copolymer poly(4-trimethylsilylstyrene)-block-polystyrene (PSSi-b-PS). PSBA-b-PS is obtained through highly selective reaction of PSSi-b-PS with BBr3 at room temperature and subsequent hydrolysis of the BBr2-functionalized intermediate. Transmission electron microscopy studies demonstrate that PSBA-b-PS undergoes pH dependent micellization in aqueous solution. Different morphologies could be realized by using different mixtures of water and organic solvents. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2438-2445, 2010