Abstract View
Experimental Verification of the Kinetic Theory of Gelation
Christopher Sorensen, RAIYA EBINI, Kansas State University
Abstract Number: 40
Working Group: Aerosol Physics
Abstract
The sol-to-gel transition has been intensively studied and as all good aerosol scientists know, aerosols can gel. There are three main descriptions to understand this process: Kinetic, percolation, and phase separation, yet no consensus has emerged. Here we report studies of colloidal gelation of 40nm nanospheres. We chose a dilute monomer volume fraction to allow for a full investigation of the gelation from dilute sol to percolated gel. Growth of fractal aggregates was monitored by combining small angle static light scattering (SASLS), dynamic light scattering (DLS) techniques, and transmitivity measurements. The data verify the predictions of a kinetic theory, the ideal gel point (IGP) theory, where three regimes of kinetics are expected. First, the well-known cluster-dilute regime, with a kinetic exponent of z = 1 was observed, followed by a cluster-dense regime with an enhanced kinetics and z ≃ 2, and finally, a gelation regime was observed where the aggregate growth slows and ceases to grow at the IGP predicted size, Rg,G. We conclude that kinetics provides a complete theory of the gelation process from dilute sol to percolated gel. It will be interesting to expand this work into aerogels.