High-strength and pH-responsive self-healing polyvinyl alcohol / poly 6-acrylamidohexanoic acid hydrogel based on dual physically cross-linked network

The fabrications of hydrogel with both good mechanical properties and self-healing ability are still challenging issues. Herein, we report a high strength and pH responsive hydrogel based on polyvinyl alcohol (PVA) and poly 6-acrylamidohexanoic acid (PAACA) using dual physically cross-linking strategy. Owing to the H-bonds and the crystallites domains, the prepared hydrogel present considerable tensile strength. Meanwhile, the PAACA could facilitate the crystallization behavior of PVA, resulting in the fabrication of hydrogel through one simple freezing step instead of repeated freeze/thaw cycles. Furthermore, the hydrogel exhibit reversible pH responsive self-healing and swelling property stemming from protonated and deprotonated of the carboxyl groups in PAACA side chains, allowing external control over the healing and swelling process.