New polysaccharide-based bio-super-absorbents for water stress control in agriculture: preparation and properties

In this study, glucose units within the polymeric structure of cellulose were transformed into 2,4-dihydroxy-3-(1-hydroxy-2-oxoethoxy) butanal, denoted as cellulose containing dialdehyde units, through oxidation with sodium periodate. Subsequently, a Horner–Wadsworth–Emmons reaction with triethyl phosphonoacetate was employed to convert dialdehyde cellulose (DACs) into cellulose containing sodium 2,3-dipropenoate units (DACAcr). The modified cellulose underwent thorough characterization using various methods and was utilized as both a copolymer of acrylic acid and itaconic acid and a grafting agent to synthesize an environmentally friendly super-absorbent material, designated as DACAcr-g-poly(AA-IA). The introduction of double bonds at the C₂ and C₃ positions of β-d-glucose units is supposed to enhance linkages between cellulose and acrylic acid by copolymerization and increased the overall number of hydrophilic carboxylate groups, resulting in the development of a more robust, flexible and expanded network for the swelling process in water. This network exhibited the capacity to efficiently absorb and store significant amounts of water, attributed to increased Bio-Superabsorbents (BioSAP) flexibility. The study delved into investigating the modification and synthesis conditions of the super-absorbent, determining the oxidation state of glucose units and evaluating the impact on water absorbency.