Chemically Crosslinked Alginate Hydrogel with Polyaziridine: Effects on Physicochemical Properties and Promising Applications

Alginate biopolymer is widely employed in many industrial fields thanks to its pleasing features of biodegradability, biocompatibility, low toxicity, and relatively low cost. The gelling process of alginate with divalent cations is fairly simple and thus it is used as a versatile biomaterial to tailor the desired mechanical and moisture properties. This study focused on developing new gel formulations to enhance the properties of calcium-alginate hydrogel (CA). The newly synthesized hydrogels, referred to as CA-CHEM gels, were chemically cross-linked with different ratios of pentaerythritol tris[3-(1-aziridinyl)propionate] (PTAP) through the reaction between the carboxylic groups of alginate and aziridines of PTAP. The reaction was successfully monitored by NMR. The new CA-CHEM gels were chemically characterized using FTIR-ATR, while SEM analysis confirmed the changes in the porosity and homogeneity of the network. Additionally, thermogravimetric analyses and mechanical properties showed improvement in degradation stability and in structural strength, compared to plain CA, with an increasing PTAP content up to 1 % w/w. Finally, the new CA-CHEM gels effectively controlled water absorption and release. In particular, CA-CHEM-1 performed as the most controlled system, making it promising for delivering aqueous cleaning solutions on water-sensitive surfaces such as a wooden historical musical instrument.