Use of a Laser Scanning Confocal Microscope to Obtain Concentration Profiles of a Diffusant in a Polymer Film

The use of laser scanning confocal microscopy (LSCM) to view textile substrates is a relatively new field. It has been used to determine fiber shapes and concentrations of a fluorescent dye in a fiber. However, this technique is limited to very low concentrations of strongly absorbing species. A new technique based on LSCM is developed for obtaining concentration profiles at much higher concentrations where the effects of absorption of the incident light cannot be ignored. Sample preparation is particularly simple. Although this new approach is specific to planar films, it permits the study of dye diffusion in polymers at normal dye concentrations and with dyes that are not traditionally considered fluorescent dyes. The concentration profiles are used to obtain the diffusion coefficient of C.I. Disperse Blue 3 in nylon 6,6 film.