Effect of additives on fabrication and properties of hydroxypropyl methylcellulose-based hydrogels

Hydrogel materials based on bio-degradable polymers have received a lot of interest owing to many potential applications. In this study, hydroxypropyl methylcellulose (HPMC) as a based polymer was cross-linked using 5 wt% of non-toxic citric acid. Polyethylene glycol (PEG) and glycerol were used as gelation accelerants. The effect of reaction temperature on the ability to cross-link the matrix was investigated using differential scanning calorimetry (DSC), thermogravimetric (TGA), and dynamic mechanical analysis (DMA). The cross-linking process could not be observed using DSC or TGA. However, the sample with PEG and glycerol exhibited the highest increase of storage modulus in DMA measurement. A completely gelled state (100% gel fraction) could be obtained in all sample types at the temperature of 140 °C for 10 h. The addition of PEG significantly improved the gel fraction of HPMC-based hydrogel. With a higher concentration of PEG, the increase of C = O groups which were a result of the esterification of citric acid and HPMC molecule was confirmed by Fourier transform infrared spectroscopy (FTIR). The sample with 1 wt% of PEG showed the highest methylene blue adsorption.