Research On The Properties Of Polymer Induced By Laser Irradiation

The discovery of conducting polymer extremely extends the range of polymer's application. Conducting polymer would have great influence on industry of electron and information as its good properties of stretchability, flexibility and workability.This letter we use laser irradiation as main experimental technique and discovered that the increase in electrical conductivity of poly(vinylidene fluoride) (PVDF) was induced by excimer laser irradiation withλ=248 nm. The electrical conductivity was found to increase from 10^-13 to 10^-4Ω^-1·cm^-1. As a result, experiments produced a transition in the property of the material from an insulator to a conductor. Optimal conditions for laser irradiation were determined in terms of the laser energy density, the repetition frequency, and the total number of laser shots. The PVDF samples were also irradiated by frequency-tripled laser and solid green laser to be compared with the experiment of KrF excimer laser irrdiation.We discussed the mechanics of increasing conductivity in the light of X-ray Diffraction, Raman Spectroscopy,Infra-red spectroscopy, x-ray Photoelectron Spectroscopy, Optical Microscope and Scan Electronic Microscope (SEM). We can draw the conclusion that the laser broke the C-F bond and there were single crystal graphite and polycrystalline graphite on the surface of PVDF after laser irradiation which results in the increase of electrical conductivity. We also took full advantage of method of Raman spectra, Raman mapping, SEM, Atomic Force Microscope and Energy Dispersive X-ray Spectrometer to discusse the thickness of the conducting layer and the surface microstructure in irradiated PVDF and concluded that the thickness of conducting layer of the sample is approximately 7.5μm and the formation of graphite after excimer laser irradiation is non-uniform which is related to the initial sample. These three key problems are very important to the further research on interacting mechanics between laser and polymer.Other kinds of important polymer and crystals such as PTFE, EP, ABS, POM, PSF, SrTiO₃ and LaAlO₃ were also irradiated by KrF excimer laser and there were no changes of property in dielectric, piezo-electricity and electrical conductivity being found.