AbstractAqueous polyurethane dispersions derived from various polycarbonatediols, carboxylic diols, and m‐di(2‐isocyantopropyl)benzene (TMXDI) were prepared by a solvent‐free process. The dispersing procedure was investigated by Fourier transform infrared spectroscopy and it was found that the use of TMXDI could avoid the over hydrolysis of the isocyanate groups during dispersing in water. The molecular weight tends to reach a maximum around an NH2/NCO ratio during chain extension of 0.8 : 1.0. The particle size, tensile properties, thermal properties, and dynamic mechanical properties of the polyurethane dispersions were investigated. The properties were significantly influenced by the molecular weight of the polycarbonatediols and the chemical structure of the carboxylic diols, and described by the effects of the ionic content, miscibility between the polycarbonate soft segment and the polyurethane segment, and the soft segment content. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012