A thorough understanding of the morphology of the environmental sensitive nanogels was indispensable to obtain a deeper insight on their stimuli-responsive behavior. Therefore, in this work the colloidal characterization and the study of the inner morphology were related by using light scattering technique and H-1-nuclear magnetic resonance transverse relaxation measurements combined with the Flory-Rehner theory. Different biocompatible and dual-stimuli-sensitive nanogel particles based on poly(2-diethylaminoethyl) methacrylate were synthesized using three different crosslinkers: two bifunctional and one multifunctional. All the nanogels obtained had a core-shell type heterogeneous morphology, but they presented completely different swelling behaviors due to their different crosslinking points' distribution and polymeric chains' microstructure. (c) 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 2017-2025