Micelles have been prepared by mixing poly(styrene)-block-poly(4-vinylpyridine) (PS-b-P4VP) copolymers and poly(acrylic acid) (PAA) homopolymers in organic solvents. Complexation via hydrogen bonding occurs between the P4VP and PAA blocks. Further aggregation of the accordingly formed complexes results in micelles stabilized by a corona of PS blocks. The influence of the relative lengths of the different blocks and of the quality of the solvent towards the complexes on the micellar characteristic features is studied. Soluble, non-aggregating, complexes have been observed in DMF, provided that the complexes are sufficiently small. In all other cases, the complexes were insoluble and aggregated in micelles. The size of those micelles depends strongly on the length of the P4VP blocks but only weakly on the PAA length. (c) 2007 Elsevier Ltd. All rights reserved.