A research group at the University of Tokyo has discovered a universal law that explains the change in water retention (osmotic pressure) in the process of changing from a liquid to a solid gel.
In gelation represented by changes such as gelatin liquid solidifying into jelly and milk solidifying into yogurt, the osmotic pressure decreases significantly as the liquid solidifies.The osmotic pressure is a factor that determines the water retention capacity of the gel, and as can be seen from the fact that the liquid seeps out on the surface of the jelly or yogurt, the water retention capacity decreases due to gelation, but this water retention capacity (osmotic pressure) Until now, no law has been known to explain the change in the osmotic pressure in a unified manner.
This time, the researchers made separate samples that imitated the gelation process, and patiently performed long-term measurements to accurately measure changes in osmotic pressure during the gelation process.As a result of analyzing the measurement results from the viewpoint of "universal equation of state", it was found that the osmotic pressure in the gelation process can be explained by a common universal law regardless of the type of substance such as jelly or yogurt.
In 1972, French physicist Dr. Dugennes discovered the commonality between the phenomenon of iron turning into a magnet (magnetic transition) and polymer solutions, and was later awarded the Nobel Prize in Physics.This "polymer-magnetic material correspondence" is also common to various critical phenomena such as the superfluid transition of liquid helium and the phase transition of quarks and gluons of elementary particles, and it is said that polymer solutions also have very long polymer chains. It has been found to show similar universality from macroscopic properties.
Nearly 50 years later, this research started with the idea that Dr. Dugenne's idea might hold true in the gelation process, and as a result, not only the polymer solution but also the gelation process follows the same universal equation of state. It became clear for the first time in the world.
Since this research has provided material design guidelines for controlling the water retention capacity of gels, it is expected that the development of new soft and wet gel materials that can be applied as medical materials will be further accelerated.
Paper information:[Physical Review Letters] Universal Equation of State Describes Osmotic Pressure throughout Gelation Process
