Film formation from nanosized copolymeric latex particles: A photon transmission study

The photon transmission technique was used to monitor the evolution of tran sparency during film formation from nano-sized copolymeric latex particles. The latex films were prepared from poly(methyl methacrylate-co-butyl metha crylate) (P(MMAco-BMA)) particles which were produced by microemulsion poly merization, These films were annealed at elevated temperatures in various t ime intervals above the glass transition temperature (T-g) of P(MMA-co-BMA) . It is observed that the transmitted photon intensity (I,) from these film s increased as the annealing temperature increased. There are three differe nt film formation stages, These stages are explained by the void closure, h ealing, and interdiffusion processes, respectively. The activation energies for viscous flow (DeltaH approximate to 16 kcal/mol), minor chains (DeltaE (H) approximate to 27 kcal/mol), and backbone motion (DeltaE(b) approximate to 132 kcal/mol) were obtained using various models. Void closure (tau (v) , T (v)) and healing points (tau (H), T (H)) were determined. Using the tim e-temperature pairs, void closure and healing activation energies were meas ured and found to be 21 and 30 kcal/mol, respectively. (C) 2001 Academic Pr ess.