A series of interpenetrating polymer networks (IPNs) of polyurethane/polyacrylates were synthesized. Their morphology was investigated by means of small-angle X-ray scattering (SAXS) and transmission electron microscope (TEM). The influence of an active positive charge group (-N(CH3)(2)) on the phase structure of the aforementioned IPNs was studied. The results show not only that the size of phase segregation zones varies with composition but also that the specific interfacial surface areas have a maximum when the weight ratio of polyurethane and polyacrylates is 1: 2. Moreover, the introduction of an active positive charge group (-N(CH3)(2)) is an important way of increasing the miscibility between two component polymers.