Nucleation, Growth, Fractal Aggregation, and Late-Stage Coarsening on Structural Development of Polymer Physical Gels
figureposted on 27.07.2004, 00:00 by Che-Min Chou, Po-Da Hong
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 Hv and Vv scattering intensity distributions over the experimental q range and holds the truth of the gel structural development in the late-stage coarsening process.