화학공학소재연구정보센터
Langmuir, Vol.15, No.4, 1364-1372, 1999
Confocal and scanning probe microscopy of surface modifications of thin polymer films induced by infrared diode laser irradiation
The morphology of polymer films doped with an infrared dye could be modified significantly with single pulses of a few microseconds from a diode laser with a wavelength of 839 nm. The infrared light was focused into a Gaussian spot having a power density in the center of up to 200 kW/cm(2). Atomic force microscopy was used to characterize the influence of the infrared-laser power, the pulse width, and the concentration of the embedded infrared dye on the restructuring of the topography of the doped polymer films. Furthermore, the incorporation into the polymer matrix of a thermolabile sulfonium salt combined with acridine as an acid-sensitive fluorescent probe allowed the visualization of the thermally affected area of the irradiated film using laser scanning confocal fluorescence microscopy and scanning near-field optical microscopy. The comparison between irradiated films with poly(methylmethacrylate) and poly(styrene-co-butyl methacrylate) revealed different morphologies in the restructured areas, indicating the important influence of the polymer matrix on the laser action. Experimental evidence was found for the ejection of small droplet like fragments from the irradiated film area. Furthermore, the impact of the infrared irradiation on the film morphology in this study shows close similarities with the restructuring of doped polymer films upon ultraviolet irradiation in earlier reports by Srinivasan, suggesting similar mechanisms for the restructuring at these different irradiation wavelengths.