Research Information System
COMPOSITE INTERFACES, vol.10, no.6, pp.547-566, 2003 (SCI-Expanded)
Fast transient fluorescence technique (FTRF), which uses a Strobe Master System (SMS), is used to study swelling and drying of disc shape heterogels. Disc shape heterogels are prepared by free radical copolymerization (FCC) of methyl (methacrylate) (MMA) and styrene (S) with ethylene glycol dimethacrylate (EGDM). Pyrene (P-y) is introduced as a fluorescence probe during polymerization and lifetimes, iota, of P-y are measured during the in-situ swelling process. Chloroform was used as an organic vapor agent to induce gel swelling. It is observed that iota values decrease as swelling proceeds. The Li-Tanaka equation is used to determine the time constant, iota(c), and cooperative diffusion coefficients, D-c, for the swelling processes. Lifetimes of pyrene increase during drying. An empirical equation is introduced to determine the desorption coefficient, D, for drying. Heterogels with high S content swell and dry much more slowly than heterogels with low S content.