In this work PEGylated polyester-based nanoparticles (NPs) for drug delivery applications were synthetized through emulsion free radical polymerization. These NPs are produced starting from functionalized macromonomers whose average chain length can be tuned in a controlled way. Since the degradation of these NPs occurs through the hydrolysis of side chains, by tuning their length it is possible to obtain NPs with a controllable degradation time, comparable to data obtained with NPs internalized into cells. The long-term colloidal stability of these NPs in isotonic environment has been assessed through dynamic light scattering measurements and their degradation rate in cell medium has been proved to be fast and controllable. The NP behavior in gastric and intestinal solution was also studied.