Latex film formation and dissolution: A fluorescence study

A new technique based on steady state fluorescence (SSF) measurements is in troduced for studying dissolution of polymer films. These films are formed from naphthalene (N) and pyrene (P) labeled poly(methyl methacrylate) (PMMA ) latex particles, sterically stabilized by polyisobutylene (PIB). Annealin g was performed above T-g,at elevated temperatures for 30 min time interval s for film formation. Film formation from these latexes is monitored by the extent of energy transfer from N to P using SSF and by the transmitted pho ton intensity from these films using UV visible (UVV) methods. Desorption o f P labeled PMMA chains was monitored in real-time by the change of pyrene fluorescence intensity. Dissolution experiments were performed in various s olvents with different solubility parameters, delta, at room temperature. D iffusion coefficients, D, in various solvents were measured and found to be around 10(-) (10) cm(2)/s. Strong relationships between D and delta were o bserved. Diffusion activation energy was measured by performing dissolution experiments in toluene-heptane mixtures at elevated temperatures and deter mined to be 24.4 kcal mol(-1).