Our paper on gel-gel phase separation has been published in Nature Materials.
When hydrogels with a PEG backbone were made at very low concentrations (~1 wt%), we discovered a phenomenon of phase separation between the dense and dilute phases of the polymer after gelation. When gels are made at the critical point of gelation, the more water is added to the hydrophilic polymer, the more the phase separation progresses, which is a unique phenomenon. This phenomenon, so to speak, also called gel-gel phase separation, is unique in that it occurs in a system of PEG, a hydrophilic polymer, and is expected to be applied as a culture medium for cell culture.
This research was led by Professor Takamasa Sakai's research group at the University of Tokyo, and we contributed to the structural analysis by small-angle X-ray scattering. Small-angle X-ray scattering revealed the progress of phase separation and the structure of polymers inside the dense phase after phase separation.
Ishikawa, S.; Iwanaga, Y.; Uneyama, T.; Li, X.; Hojo, H.; Fujinaga, I.; Katashima, T.; Saito, T.; Okada, Y.; Chung, U.; Sakumichi, N.; Sakai, T. Percolation-Induced Gel–Gel Phase Separation in a Dilute Polymer Network. Nature Materials 2023, 1–7.