We tested the stability of the synthesized HA derivatives by 1 H NMR spectroscopy and SEC analysis. The polymers were stored as solids at room temperature in the dark for 15 months. At different time points, samples were dissolved at 15 mg mL -1 in D2O and 1 H NMR spectra were recorded (Figure ). The NMR spectra of HA-AE and HA-NB showed no changes in the vinyl proton signals in the 15 months, whereas HA-MA showed additional peaks in the spectrum already after 4 months of storage. The stability studies confirm the higher shelf-life of ene-precursors, presumably as consequence of insusceptibility to autopolymerisation of AE and NB groups. A higher stability of the amide and ether groups in HA-AE and -NB vs. the ester group in HA-MA is also expected.