Determination of reaction activation energy during gelation in free radical crosslinking copolymerization using the steady-state fluorescence method

SYNOPSIS The steady-state fluorescence technique was used to study the sol-gel transition in free radical crosslinking copolymerization of methyl methacrylate and ethylene glycol dimethacrylate (EGDM). Pyrene methyl pivalate was used as a fluorescence probe for the in situ polymerization experiments. The times required for the onset of gelation t, and the critical exponent /3 were recorded for various EGDM contents and at different polymerization temperatures. A simple kinetic model was used to interpret the experimental gel point data. The results show that the fluorescence technique can be used to measure the critical exponent /3, the gel point tc, and the activation energy during sol-gel phase transition processes. 0 1996 John Wiley & Sons, Inc.