The current investigation describes in detail the influence of the polymer molar mass as well as polymer-solvent interactions on the formation of nanoparticles using the nanoprecipitation methodology. For this purpose, a homologous series of poly(methyl methacrylate)s with molar masses ranging from 7,700 to 274,000 g mol-1 was prepared. Subsequently nanoprecipitation was performed in an automated and systematic manner using liquid handling robots and a variation of different initial concentrations of the polymers and solvent/nonsolvent ratios. To elucidate information about the polymer behavior in the solvents used for the nanoprecipitation procedure (acetone, tetrahydrofuran), intrinsic viscosity measurements were performed. The nanoparticle formulations were examined in terms of particle size and size distribution, particle shape as well as zeta-potential. The conditions for the preparation of stable and uniform nanoparticles, regardless of molar mass and hydrodynamic volume of the initial polymer, were determined. (C) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012