2025 Volume 74 Issue 2 Pages 82-83
The Flory-Huggins (FH) theory is widely used to describe the phase separation and properties of polymer gels, despite its inaccuracy at low concentrations. Recent experiments on tetra-PEG gels have revealed that the osmotic pressure of gels follows a universal scaling law using the polymer-solvent volume ratio, providing a more accurate description than FH theory. The discrepancy between FH theory and the scaling law can significantly impact predictions of gel swelling and phase separation. Moreover, a novel phenomenon called “gel-gel phase separation” has been discovered in extremely dilute gels, which cannot be explained by conventional FH theory. Gel-gel phase separation results in hydrophobic, cell-adhesive gels with potential applications in tissue engineering. These findings highlight the need for new theoretical frameworks to describe the properties of gels in the dilute regime and the potential for developing novel gel materials with unique properties and functions.
