Hydrogels: pH-sensitive swelling and use as a sensor

Abstract

In this work pH-sensitive magnetic hydrogels are investigated for their potential as chemical sensors in aqueous media. For this purpose thin layers of pH-sensitive hydrogels were made that incorporate magnetic particles. It was found that the magnetic field caused by these magnetic hydrogels changes as a function of pH. These magnetic fields are compared with theory. The swelling process in pH-sensitive hydrogels is discussed in more detail based on numerical models. These models determine that the swelling and shrinking of a pH-sensitive hydrogel are two different processes with their own dynamics. These differing dynamics cause the shrinking process to occur at a much higher speed than the swelling process.