Because hydrogels exhibit similar properties to living tissues, they are interesting candidates for biomedical applications such as for tissue engineering. However, the weak mechanical properties of hydrogels are often a drawback. Various strategies have been developed to improve the mechanical strength and the stretchability of hydrogels, among them, the use of polymeric nanoparticles that are able to act as crosslinkers of the hydrogel and to absorb energy during stretching. The present project investigated the possibility to use hyperbranched polyglycerols (HPGs) to reinforce poly(acrylic acid) hydrogel, which is a cheap biocompatible hydrogel that is fragile. HPGs are three dimensional macromolecules that bear several hydroxyl groups at the surface of their structures, which allow the formation of multiple chemical crosslinks of the poly(acrylic acid) chains by the esterification of their carboxylic groups. After having synthesized poly(acrylic acid) (PAA) hydrogels by free-radical polymerization, in presence of different amounts of HPG;  the final composition of the samples was determined by TGA and the esterification was confirmed by FTIR. The impact of the HPG/PAA proportion on the phase separation, on morphology and water uptake was evaluated.