Interdiffusion of polymer chains during latex coating

The fluorescence method was used to study the interdiffusion of polymer chains during annealing of latex above its glass transition temperature (T_g). The latex film was prepared from mixture of naphthalene (N) (donor) and pyrene (P) (acceptor)-labeled poly(methyl methacrylate) (PMMA) latex particles. Heptane was used as the coalescent agent. A steady-state fluorescence technique was employed to measure the amount of direct nonradiative energy transfer from N to P during the interdiffusion of polymer chains across the particle–particle junction. Various latex films with different latex contents were used to measure the percentage critical occupation for the reliable steady-state fluorescence measurements. Diffusions activation energies in these latex films were measured and found to be around 30 kcal/mol, which was attributed to the backbone motion of PMMA chains.