Ion-triggered reconfigurable hydrogels with salt-enhanced mechanical and swelling properties via network topological adaptation
4 affiliations
- 1School of Petroleum Engineering, China University of Petroleum (East China), Qingdao, China
- 2College of Chemical Engineering, Qingdao University Science and Technology, Qingdao, China. [email protected]
- 3School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
- 4School of Petroleum Engineering, China University of Petroleum (East China), Qingdao, China. [email protected]
Abstract
Hydrogels typically deteriorate in high salinity due to electrostatic screening and solvent-quality loss. Here, we report a double network hydrogel, composed of poly(AMPS)(2-acrylamido-2-methylpropane sulfonic acid) and zwitterionic AM-SBVI (acrylamide-sulfobetaine vinylimidazole) that strengthens while swelling in brine. Upon salt exposure, the network undergoes ion-triggered topological reconfiguration, the intrachain zwitterionic loops open and re-form as inter-network SBVI + -AMPS − bridges, which yields a higher effective bridge density v e , at lower polymer fraction(Φ). The hydrogel demonstrates a 3.4-fold increase in tensile strength and a 2.1-fold enhancement in equilibrium swelling ratio in 200 g/L NaCl compared to deionized water. Small-angle X-ray scattering (SAXS) and X-ray photoelectron spectroscopy (XPS) confirm the ion-mediated decoupling of crosslinking domains and redistribution of charge density. Moreover, simulation calculation suggests a more strong interaction between SBVI and AMPS under high salinity water. Coreflooding experiment demonstrates robust injectability and flow-resistance characteristics under high salinity porous rock. A deep analysis concerts swelling/rheology into three descriptors, v ₑ, χ (Flory-Rehner inversion), and f loop (loop fraction from bridge capacity). We find that salt contents raise and depress f loop toward zero. This, the elastic cost term, F el increases but is compensated by F assoc (stabilization from loop to bridge), while F diss from Donnan partioning is small. F mix that related to χ shifts quite small indicated a strong interaction between the hydrogel with brine. This quantitative mechanism explains the simultaneous gains in swelling and modulus and provides rational design rules to engineer salt-adaptive hydrogels for subsurface and biointerfaces.
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BibTeX
@article{ren2026iontriggered,
title = {{Ion-triggered reconfigurable hydrogels with salt-enhanced mechanical and swelling properties via network topological adaptation}},
author = {Lingling Ren and Guoxuan Ma and Zheng Wang and Shuang Liu and Haoran Cheng and David A. Weitz and Liyuan Zhang},
journal = {Nature Communications},
year = {2026},
month = may,
doi = {10.1038/s41467-026-73723-8},
url = {https://doi.org/10.1038/s41467-026-73723-8},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - Ion-triggered reconfigurable hydrogels with salt-enhanced mechanical and swelling properties via network topological adaptation
AU - Lingling Ren
AU - Guoxuan Ma
AU - Zheng Wang
AU - Shuang Liu
AU - Haoran Cheng
AU - David A. Weitz
AU - Liyuan Zhang
PY - 2026
DA - 2026/05/26
JO - Nature Communications
DO - 10.1038/s41467-026-73723-8
UR - https://doi.org/10.1038/s41467-026-73723-8
AB - Hydrogels typically deteriorate in high salinity due to electrostatic screening and solvent-quality loss. Here, we report a double network hydrogel, composed of poly(AMPS)(2-acrylamido-2-methylpropane sulfonic acid) and zwitterionic AM-SBVI (acrylamide-sulfobetaine vinylimidazole) that strengthens while swelling in brine. Upon salt exposure, the network undergoes ion-triggered topological reconfiguration, the intrachain zwitterionic loops open and re-form as inter-network SBVI + -AMPS − bridges, which yields a higher effective bridge density v e , at lower polymer fraction(Φ). The hydrogel demonstrates a 3.4-fold increase in tensile strength and a 2.1-fold enhancement in equilibrium swelling ratio in 200 g/L NaCl compared to deionized water. Small-angle X-ray scattering (SAXS) and X-ray photoelectron spectroscopy (XPS) confirm the ion-mediated decoupling of crosslinking domains and redistribution of charge density. Moreover, simulation calculation suggests a more strong interaction between SBVI and AMPS under high salinity water. Coreflooding experiment demonstrates robust injectability and flow-resistance characteristics under high salinity porous rock. A deep analysis concerts swelling/rheology into three descriptors, v ₑ, χ (Flory-Rehner inversion), and f loop (loop fraction from bridge capacity). We find that salt contents raise and depress f loop toward zero. This, the elastic cost term, F el increases but is compensated by F assoc (stabilization from loop to bridge), while F diss from Donnan partioning is small. F mix that related to χ shifts quite small indicated a strong interaction between the hydrogel with brine. This quantitative mechanism explains the simultaneous gains in swelling and modulus and provides rational design rules to engineer salt-adaptive hydrogels for subsurface and biointerfaces.
SN - 2041-1723
ER -