Universal Kinetics of the Sol-to-Gel Transition

A comprehensive theory encompassing the kinetics of sol-to-gel transition is yet to be formulated due to break-down of the mean-field Smoluchowski Equation. Using high temporal-resolution Monte Carlo simulation of irreversible aggregation systems, we show that this transition has three distinct regimes with kinetic exponent z ranging between 1 and 2, corresponding to aggregation of sol clusters proceeding to the ideal gel point (IGP); z ranging between 2 and 5.7 for gelation of sol clusters beyond IGP; and z ranging between 2 and 3.5 for a hitherto unidentified regime involving aggregation of gels when monomer-dense. We further establish universal power-law scaling relationships that connect the kinetics of these three regimes.