The development of a waterborne acrylic binder that can be formulated into zero VOC paints requires the tuning of film formation under difficult conditions, hardness, and flexibility properties. To meet these requirements, a model of the 'ideal' film was developed and polymers were synthezised to comply with this model. The choice of particle size and glass transition temperature (T g ) of the polymer phases were the key parameters in producing the desired film morphology. However, to ensure good mechanical properties, it was also crucial to optimize the interaction between the polymer phases by varying both the polymer composition and the stabilization of the latex.