MODELING OF SWELLING BY FLUORESCENCE TECHNIQUE IN POLY(METHYL METHACRYLATE) GELS

A novel technique based on in-situ steady-state fluorescence (SSF) mea surements is introduced for studying swelling processes in gels formed by free radical cross-linking copolymerization (FCC) of methyl methac rylate (MMA) and ethylene glycol dimethacrylate (EGDM) in toluene. Gel s were prepared at 75 degrees C for various toluene contents with pyre ne (Py) as a fluorescence probe. After drying these gels, swelling and desorption experiments were performed in toluene at 50 degrees C by r eal-time monitoring of Py fluorescence intensity. A correction method was developed to obtain pure swelling curves, by using desorption curv es of Py molecules. Li-Tanaka equation was employed to produce swellin g parameters. Cooperative diffusion coefficients (D-c) were measured a nd found to be around 10(-6) cm(2)/s for gels swollen in toluene. (C) 1997 John Wiley & Sons, Inc.