In situ photon transmission technique for monitoring phase separation in real time during gelation

In situ, real time photon transmission technique was used to monitor the fo rmation of heterogeneities during the free-radical crosslinking polymerizat ion of acrylamide in the presence of N,N'-methylenebis(acrylamide) (BAAm) a s a crosslinker. Two different gelation experiments were performed with var ious BAAm and water contents separately at room temperature. It was observe d that the transmitted photon intensity, I-tr decreases dramatically at a c ertain time, in both type of experiments during the gel formation process f rom interconnected microgels. Decrease in I-tr was interpreted in terms of phase separation during gelation. The extent of phase separation was measur ed depending on the crosslinker content and on the degree of monomer diluti on during the gel formation process.