Formation of inhomogeneities in polyacrylamide gel in the course of frontal polymerization

The deformation of gas bubbles in the course of photoinduced polymerization of polyacrylamide gel in monomer solution under microgravity conditions has been studied experimentally. The use of optical methods allows one to identify the specific features of changes in the shape of gas bubbles and to correlate these changes with different stages of polymerization. At the initial stage of the polymerization reaction, the development of gel inhomogeneities is caused by reflection and scattering of the initiating light and, correspondingly, by different rates of gel formation near the surface of a gas bubble. After its contact with the polymerization front, further deformation of the bubble is caused by the inhomogeneous development of the reaction in the formed gel. Using the interference method, the characteristic dimensions of structural inhomogeneities in the formed gel induced in the vicinity of the transparent inclusion are measured.