Phase behavior of methacrylic acid, poly(ethylene glycol) methyl ether, and poly(ethylene glycol) methacrylate in aqueous solutions

Abstract

The main issue of this manuscript is the exploration of the solubility of methacrylic acid (MA), and the oligomers of poly(ethylene glycol) methyl ether (MPEG), poly(ethylene glycol) methacrylate (PEGMA), and a mixture of MA and PEGMA. These solutions obey to the class of associating aqueous solutions as hydrogen bonding plays an essential role. All solutions are miscible at ambient temperature. Only a small fraction of the order of 10−5 molecules is involved in a process of aggregation forming about 0.4 μm diameter large colloids whose volume fraction enhances above 70 °C. This increase of aggregation is going hand and hand with phase separation of the solution at temperatures at about 70 °C and above. Spinodal and binodal temperatures of the solutions were determined from thermal composition fluctuations following mean field and renormalized 3D-Ising behavior in dependence of the distance from the spinodal phase boundary.