Ultrastretchable, Tough and Superabsorbent Hydrogel with Spherical Polyelectrolyte Brushes as Macromolecular Crosslinkers
Yu Cang, Rui Zhang, Xuhong Guo
State Key Laboratory of Chemical Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
Abstract: Hydrogels were three-dimension networks of chemical or physical crosslinked polymer chains. The adequate mechanical properties were necessary for applications of hydrogels, which have been important characteristics to evaluate their performance. Many strategies were devoted to robust hydrogel synthesis, such as introduction the coexisting network to form double-network hydrogel, using inorganic/macromolecular crosslinkers to form homogenous networks. All these methods could improve the mechanical properties by increasing the crosslinked density of network, but at expense of water absorbency property. We used spherical polyelectrolyte brushes (SPBs) as crosslinkers to form ionic hydrogel which was tough and could absorb considerate water simultaneously. The polymer chains of SPBs was modified with thiol groups and covalent bonded with monomer via Michael-type addition reaction. The SPBs hydrogel was enough robust to sustain high level compression and stretched up to more than 40 times their original length. Besides, the water absorbency was surprisingly large that the swelling ratio reached above 3000 (Figure 1). The ideal combination of mechanical properties and water absorbency would open a new scope for hydrogels.
Keywords: spherical polyelectrolyte brushes, hydrogel, superabsorbent, crosslinker
Figure 1. (A) Optical images showing the hydrogel with high mechanical properties. (B) The elongation. elastic modulus and tensile test of hydrogel with different concentration of monomers and crosslinkers.