Modification of PET Foil by 150 keV Li⁺ Ion Implantation

Abstract

Very thin (3 µm in thickness) polyethylene terephthalate polymer foils were implanted with 150 keV Li + with fluences in the range from 1×10 14 cm −2 up to 2×10 16 cm −2 . Modification of the irradiated polymer microstructure was studied with the Fourier transform infrared spectroscopy and Raman spectroscopy. Breaking of a variety of chemical bonds followed by the formation of carbon clusters made of sp 2 C was proved. The dominance of the rings in the carbonized, graphite-like subsurface layer is demonstrated based on the fact that the G band prevails in the Raman spectra for larger Li + fluences. The rise of the absorbance within 200-800 nm is observed. Tauc's plots analysis enables the estimation of optical bandgap values that decrease from 3.95 eV (pristine polyethylene terephthalate) down to 1.4 eV (fluence of 2 × 10 16 cm −2 ). This change is not as dramatic as in the case of heavier projectiles like K + or Na + . Reduction of surface resistivity by more than 2 orders of magnitude is observed in the case of the sample irradiated with the fluence 1 × 10 16 cm −2 , and this effect is much smaller than that induced by the heavier projectile bombardment with the same fluence. topics: polymers modification, ion implantation, polyethylene terephthalate (PET)