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Download fileA Self-Healing and Highly Stretchable Polyelectrolyte Hydrogel via Cooperative Hydrogen Bonding as a Superabsorbent Polymer
journal contribution
posted on 22.04.2019, 19:03 authored by Esra Su, Mine Yurtsever, Oguz OkayPoly(2-acrylamido-2-methyl-1-propanesulfonic
acid) (PAMPS) hydrogels
are attractive materials for various application areas due to their
pH-independent large swelling capacities. However, their covalently
cross-linked network structure leads to a brittle behavior even at
low strains. We present here for the first time highly stretchable
superabsorbent PAMPS hydrogels formed via H-bonds entirely that are
stable in water. UV polymerization of AMPS in aqueous solutions at
23 ± 2 °C without a chemical cross-linker produces hydrogels
with large swelling capacities exceeding 1000 times their original
mass. Although the hydrogels are stable in water, they easily dissolve
in chaotropic solvents, suggesting that they form via H-bonding interactions
between PAMPS chains. We show that the high molecular weight of the
primary chains of PAMPS hydrogels formed via UV polymerization contributes
to the H-bonding cooperativity and hence is responsible for their
stability in water. Incorporation of N,N-dimethylacrylamide (DMAA) segments into the physical PAMPS network
further increases the molecular weight of the primary chains, leading
to enhanced mechanical strength of the hydrogels. PAMPS/DMAA hydrogels
in their as-prepared states exhibit a high modulus (up to 0.41 MPa),
tensile fracture stress (up to 0.57 MPa), and high stretchability
(∼1000%) together with an extraordinary swelling capacity (up
to ∼1700 g·g–1) and complete self-healing
efficiency.