Anti-swelling P(DAC-co-NaSS-co-VDT) polyampholyte hydrogel with solvent displacement and salinity enhanced wet strength and adhesion.

Polyampholyte (PA) hydrogels in general possess excellent mechanical properties, but their underwater applications are largely limited due to swelling induced dramatically reduced strength and poor wet adhesion, especially in high salinity environments. Here, we report our approach to fabricating an anti-swelling poly(acryloyloxyethyltrimethyl ammonium chloride (DAC) -co- sodium p-styrenesulfonate (NaSS) -co- 2-Vinyl-4,6-diamino-1,3,5-triazine (VDT), or P(DAC -co- NaSS -co- VDT), PA hydrogel by introducing multi-hydrogen bonding capable functional VDT moieties into the DAC/NaSS coexisting and cation/anion ratio easily tunable PA network. The mechanical properties of the P(DAC -co- NaSS -co- VDT) hydrogel in bulk and at interface were controllable with dimethyl sulfoxide (DMSO)/H 2 O solvent displacement and Hofmeister effect in a wide salinity range, exhibiting maximum tensile strength, Young's modulus, and wet adhesion toughness of 7.6 MPa, 200 MPa, and 350 J m−2, respectively. The anti-swelling and strong P(DAC -co- NaSS -co- VDT) PA hydrogel developed in this work may find great potential in underwater sensing and sewage treatment as well as for many biomedical applications. • Polyelectrolyte P(DAC -co- NaSS -co- VDT) hydrogels can maintain volume stability in different salt solutions. • Hofmeister effect improves the mechanical properties of hydrogels. • The underwater adhesion of hydrogel can be regulated by solvent exchange. [ABSTRACT FROM AUTHOR]