Raman Scattering Study during the Dehydration Process of Polyacrylamide Gel

Raman scattering experiment was carried out simultaneously with weight measurement during the dehydration process of polyacrylamide (PAAm) gel. Anomalies in the Raman spectrum were observed when the time dependence of the weight altered: around the first characteristic time, a shoulder emerged on the skirt of the low-lying diffusive central mode, and then around the second one, the shoulder changed into a peak (which resembled the “boson peak" commonly observed in glass) in addition to the disappearance of the central diffusive mode and an O–H stretching mode. The correlation between the spectral change and the time dependence of the weight demonstrated the effect of increase in the polymer chain interaction on the gel's dynamical properties.