Simple One Pot Preparation of Chemical Hydrogels from Cellulose Dissolved in Cold LiOH/Urea

Jiayi Yang; Bruno Medronho; Björn Lindman; Magnus Norgren

doi:10.3390/polym12020373

Simple One Pot Preparation of Chemical Hydrogels from Cellulose Dissolved in Cold LiOH/Urea

Polymers (Basel). 2020 Feb 7;12(2):373. doi: 10.3390/polym12020373.

Authors

Jiayi Yang¹, Bruno Medronho^{1

2}, Björn Lindman^{1

3

4}, Magnus Norgren¹

Affiliations

¹ FSCN, Surface and Colloid Engineering, Mid Sweden University, SE-851 70 Sundsvall, Sweden.
² MED-Mediterranean Institute for Agriculture, Environment and Development, Faculty of Sciences and Technology, Campus de Gambelas, Ed. 8, University of Algarve, 8005-139 Faro, Portugal.
³ Physical Chemistry, University of Lund, SE-221 00 Lund, Sweden.
⁴ Chemistry Department, University of Coimbra, 3004-504 Coimbra, Portugal.

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.

Keywords: LiOH/urea; Michael addition; cellulose hydrogel; methylenebisacrylamide.

Abstract

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