AbstractAt concentrations above 15 wt-%, aqueous solutions of mixtures of aminoterminated poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) block copolymers (PEPE) and hyaluronic acid show a reversible sol-gel-transition upon change of temperature. For non-aminoterminated PEPEs, this gel transition could be related to micellization and subsequent colloidal jamming of the micelles. Here, the mechanism of gelation for the aminoterminated compound is investigated by fluorescence spectroscopy and 1H-NMR spectroscopy. The aminoterminated PEPE also form micelles. The onset of micellization is temperature and concentration dependent, and can be tuned to 20–40 °C. Interestingly, with increasing molecular weight of the hyaluronic acid component, the micellization is observed at lower concentrations.