2024-05-15 バージニア工科大学(VirginiaTech)
＜関連情報＞
- https://news.vt.edu/articles/2024/05/science-physics-flexible-robots.html
- https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.132.208201
化学応答性ハイドロゲルの拡散泳動による高速膨潤 Diffusiophoretic Fast Swelling of Chemically Responsive Hydrogels
Chinmay Katke, Peter A. Korevaar, and C. Nadir Kaplan
Physical Review Letters Published 15 May 2024
DOI:https://doi.org/10.1103/PhysRevLett.132.208201
ABSTRACT
Acid-induced release of stored ions from polyacrylic acid hydrogels (with a free surface fully permeable to the ion and acid) was observed to increase the gel osmotic pressure that leads to rapid swelling faster than the characteristic solvent absorption rate of the gel. The subsequent equilibration of the diffusing ion concentration across the gel surface diminishes the osmotic pressure. Then, the swollen gel contracts, thereby completing one actuation cycle. We develop a continuum poroelastic theory that explains the experiments by introducing a “gel diffusiophoresis” mechanism: Steric repulsion between the gel polymers and released ions can induce a diffusio-osmotic solvent intake counteracted by the diffusiophoretic expansion of the gel network that ceases when the ion gradient vanishes. For applications ranging from drug delivery to soft robotics, engineering the gel diffusiophoresis may enable stimuli-responsive hydrogels with amplified strain rates and power output.
