Sustainable synthesis and physicochemical characterization of xylan-based pH-sensitive hydrogels

The biodegradable nature of hydrogels is highly promising especially in drug delivery apart from use as fertilizer carrier and in making edible films for packaging foods. In the current study, xylan-based hydrogels were synthesized via a free-radical graft copolymerization reaction. For the synthesis of hydrogels, acrylic acid (AA) and xylan were taken as substrate, N,N-methylene-bis-acrylamide (MBA) as a cross-linker, and potassium persulfate/sodium sulfite (K 2 S 2 O 8 /Na 2 SO 3 ) as initiators. Hydrogels were synthesized using varying molar ratios of AA to xylan in 2:1, 4:1, 6:1, 8:1, and 10:1. The FTIR spectroscopy, solid-state 13 C CP/MAS NMR spectroscopy, gel mass fraction, graft yield and graft efficiency revealed the successful synthesis of hydrogels. Among all, the hydrogel with AA and xylan in a 2:1 molar ratio showed maximal swelling (6824 ± 800%), outstanding porosity (89 ± 1.9%), and the best in vitro degradation (21 ± 0.86% after 27 days). The optimized hydrogel showed 33 times more swelling at pH 6.8 than at pH 4 after 8 h of study and therefore, maybe a valuable substrate for drug administration. TGA study showed excellent thermal stability, and FE-SEM micrographs demonstrated the largest pore size of 114 ± 54 μm, also supporting the results of BET analysis for hydrogel synthesized by taking the molar ratio of AA to xylan as 2:1. Therefore, this synthesized hydrogel is anticipated to be a potential carrier for drug administration and may have significant potential in material science and biomedical applications.