Abstract
In this work, non-derivatized cellulose pulp was dissolved in a cold alkali solution (LiOH/urea) and chemically cross-linked with methylenebisacrylamide (MBA) to form a robust hydrogel with superior water absorption properties. Different cellulose concentrations (i.e., 2, 3 and 4 wt%) and MBA/glucose molar ratios (i.e., 0.26, 0.53 and 1.05) were tested. The cellulose hydrogel cured at 60 °C for 30 min, with a MBA/glucose molar ratio of 1.05, exhibited the highest water swelling capacity absorbing ca. 220 g H2O/g dry hydrogel. Moreover, the data suggest that the cross-linking occurs via a basic Michael addition mechanism. This innovative procedure based on the direct dissolution of unmodified cellulose in LiOH/urea followed by MBA cross-linking provides a simple and fast approach to prepare chemically cross-linked non-derivatized high-molecular-weight cellulose hydrogels with superior water uptake capacity.
Highlights
Increasing environmental awareness and concern have drawn considerable attention towards using the available commodities in sustainable and environmental friendly ways
Apart from the induced gelation by addition of a certain cross-linking agent, cellulose solutions are often metastable, and gelation tends to occur with temperature, pH, time or changing solvent concentration
It is well known that the stability of cellulose solutions in aqueous alkali is strongly temperature dependent
Summary
Increasing environmental awareness and concern have drawn considerable attention towards using the available commodities in sustainable and environmental friendly ways. In this respect, cellulose occupies a prominent position as the most abundant biopolymer on earth. Among the vast list of possible applications, cellulose-based hydrogels have recently attracted great attention due to their numerous advantages, such as hydrophilicity, renewability, biodegradability, biocompatibility, low cost and non-toxicity [3,4,5]. Due to superior water absorbency, these systems can be used in many different areas such as in personal healthcare [6], agriculture [7], biomedicine [8], construction [9] and among others [10]
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