HOLOGRAPHIC GRATING RELAXATION STUDIES OF PROBE DIFFUSION IN AMORPHOUS POLYMERS

Probe diffusion of camphorquinone, thymoquinone, and diacetyl in polym ers was studied by the laser-induced holographic grating relaxation (H GR) technique in polymers. The effects of changing the probe size and various parameters of the polymer, such as the molecular weight, chain conformation, and the glass transition temperature, on the probe diff usion coefficient have been investigated. Furthermore, effects of cros s-linking and plasticizing the chains of the polymer host on the probe diffusion coefficient were also studied. Temperature-dependent studie s show that except for the very low molecular weight poly(methyl metha crylate), all probe diffusion coefficient data above the glass transit ion temperature fit well to the WLF equation. (C) 1995 John Wiley and Sons, Inc.