Photon diffusion and energy transfer processes during chain interdiffusion in films formed from fluorescence labelled high-T latex particles

Abstract

Abstract Steady state fluorescence (SSF) in conjunction with Monte Carlo simulations was used to study interdiffusion of polymer chains across the particle-particle junction, during film formation from high-T latex particles. The latex films were prepared from pyrene (P) and naphthalene (N) labelled poly(methyl methacrylate) particles, and annealed in elevated time intervals above the glass transition temperature (Tg) at 180°C. Scanning electron microscopy (SEM) was used to detect the variation in physical appearance of annealed latex films. Monte Carlo simulations were performed to model the N and P fluorescence intensities (IN and IP) using photon diffusion theory. The number of N and P photons (NN and NP), emerging from the front surface of the latex film, are calculated when only N is excited where NP photons are combined of photons from radiative (NPR) and non-radiative (NPNR) energy transfer processes. In simulations, annealing time, t, and the mean free path of a photon 〈r〉 are assumed to obey the Fickian diffusion model. A novel correction method was suggested, and employed to eliminate the P intensity due to the optical variation in latex film. P intensities from solely the energy transfer processes were monitored vs annealing time, and were used to measure the polymer chain diffusion coefficient (D), which was found to be 5.9 × 10−13 cm2 s−1 at 180°C.