Evaluation of the fractal dimension of polyacrylamide during gelation and swelling

Abstract

The photon scattering method was performed to monitor the free radical crosslinking copolymerization (FCC) of acrylamide (AAm) applied with N,N'-methylenebis (acrylamide) (Bis) in time. FCC experiments were conducted using different Bis contents to create fractal-like network structures in polyacrylamide (PAAm) gels. Higher intensity values of the scattered photons, Isc were observed with increasing Bis content, BC, at a given time, which was attributed to fractal-like macrogel formation from interconnected microgels. The same gels were used in swelling experiments after drying, and increased Isc intensities from the PAAm gels were observed during the swelling process. Fractal dimensions, d during the gelation and swelling processes were measured and found to be increased as gelation and swelling times increased. According to the results obtained from the gelation measurements, it was seen that the fractal size, d, increased from very small values to 3.00. A similar increase in the range 1.00-1.66 was observed during swelling experiments.