Utilizing sorbitol to improve properties of cellulose-based biodegradable hydrogels

Hydrogels are commonly used in medicine, pharmaceuticals, and agriculture. Hydrogels absorb water by swelling and re-release this water by diffusion. Therefore, hydrogels that can absorb more water will be more useful in these applications. This study sought to synthesize a biodegradable, cellulose-based hydrogel that is more effective at absorbing and re-releasing water than those produced by current methods. We prepared crosslinkers with the ratios of moles citric acid (CA) to moles sorbitol (S) ranging from 1:6 to 90:1. We selected three crosslinkers (3:1, 10:1, and 54:1) to produce hydrogels with carboxymethyl cellulose and hydroxyethyl cellulose. We tested the compressive strength of both the dry and swollen gels and the tensile strength of the swollen gels to elucidate the gel structure. We hypothesized that a 10:1 ratio of CA to S would produce the most effective hydrogel. We compared the swelling ratios to a gel crosslinked solely with CA. 3:1 gels aided in soil moisture retention the most, revealing that a 3:1 ratio of CA to S produces the most effective gels for water absorption and re-release. Fourier Transform Infrared (FTIR) spectra demonstrated that gel production was successful and that functional groups were the same across all ratios. S improved the properties of hydrogels with different ratios necessary to maximize various parameters. These new hydrogels will be able to better improve plant survival in drought conditions, deliver drugs directly to tissues that need them, and prevent brain injury when applied to helmets.