Measurement of Diffusion in Polymer Films by Fluorescence Redistribution after Pattern Photobleaching

Fluorescence redistribution after pattern photobleaching has been used to measure the translational diffusion of a small probe molecule in a glassy polymer film. A new method has been developed employing a pattern mask with submicron dimensions to allow very slow diffusion (D ≈ 10−13 cm2/s) to be measured on a convenient time scale. The diffusion coefficient of a fluorescent dye, 7-(diethylamino)-4-nitrobenz-2-oxa-1,3-diazole, in a 1-µm-thick film of poly(methyl methacrylate) containing approximately 18% residual solvent (chlorobenzene) was found to be D = 1.6 × 10−13 cm2/s at 25 °C. © 1982, American Chemical Society. All rights reserved.