Optimization of the methacrylation of carboxymethylcellulose and use for the design of hydrogels and cryogels with controlled structure and properties

Carboxymethylcellulose (CMC) was functionalized using methacrylic anhydride (MA) to produce photo-crosslinkable methacrylated carboxymethylcellulose (mCMC). Optimization of the synthesis led to a wide range of mCMC samples with well-controlled degrees of methacrylation up to 76 ± 6%, surpassing the literature data. Aqueous mCMC formulations with different DM and concentrations of mCMC were UV-cured to obtain hydrogels, which were transformed into cryogels after freeze-drying. An innovative 13 C CP-MAS solid-state NMR methodology was used to calculate the crosslinked methacrylate density in cryogels and thus in hydrogels. These values (from 4.3 × 10 –3 to 1.3 × 10 –2 mmol/cm 3 ) were correlated with both the DM and the mCMC concentration in formulations. These parameters were used to control the material microstructure and rheological properties. As a result, the swelling ratio of hydrated cryogels could be modulated for applications requiring high or low water absorption. Moreover, it was shown that the elastic moduli G’ of the hydrated cryogels were superior to those of the original hydrogels, over the entire frequency range (0.1–10 Hz).