MEASURING CHAIN DIFFUSION-COEFFICIENTS AND ACTIVATION-ENERGY DURING COALESCENCE OF FLUORESCENCE-LABELED HARD LATEX-PARTICLES

The steady-state fluorescence (SSF) technique was used to study interd iffusion of polymer chains across the particle-particle junction durin g film formation from hard latex particles. The latex films were prepa red from pyrene (P) and naphthalene (N) labeled poly(methyl methacryla te) (PMMA) particles and annealed for long time intervals above the gl ass transition temperature (T-g) between 170 and 220 degrees C. A nove l correction method was suggested and employed to eliminate changing o f the optical density of latex films after such annealing processes. P and N fluorescence intensities solely from the energy-transfer proces ses were monitored versus annealing time and were used to measure the polymer chain diffusion coefficients D-P and D-N, which were found to be between 4.34 x 10(-14) and 7.68 x 10(-13) cm(2)/s for an annealing temperature between 170 and 220 degrees C. Using these diffusion coeff icients With the Arrhenius relation, the diffusion activation energy f or the polymer backbone was found to be 2.8 kcal/mol.