Nucleation, growth, fractal aggregation, and late-stage coarsening on structural development of polymer physical gels

By using the time-resolved small-angle light scattering (TRSALS) technique, we present the real-time measurement of the physical gelation process for a crystalline polymer. To investigate the growth kinetics, a complete picture of the gel structural formation should be differentiated into the nucleation and growth of the microgels, the diffusive aggregation of the microgels, the percolation in cluster-cluster aggregation process, and the late-stage coarsening by the Ostwald ripening process. We propose some phenomenological functions to describe the hierarchical structure of the nucleation gels. The modeling of the late-stage gel structure could be built upon the following three relevant categories: the structure of the primary particle, the nonfractal local structure of a random packing of the nearest neighbors, and the fractal correlations between the particles constituting the aggregates. The model is able to reproduce the overall behavior of H-v and V-v scattering intensity distributions over the experimental q range and holds the truth of the gel structural development in the late-stage coarsening process.