Effect of silver ion-induced disorder on morphological, chemical and optical properties of poly (methyl methacrylate)

Ion implantation is a versatile technique to tailor the surface properties of polymers in a controlled manner. In the present study, samples of poly (methyl methacrylate) (PMMA) have been implanted with 400 keV silver (Ag+) ion beam to various ion fluences ranging from 5 x 10(13) to 5 x 10(15) ions/cm(2). The effect of Ag+ ion-induced disorder on morphological, chemical and optical properties of PMMA is analyzed using Atomic Force Microscope (AFM), Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible (UV-Vis) spectroscopy. Furthermore, the electrical conductivity of pristine and implanted PMMA is measured using four probe apparatus. The AFM images revealed the growth of nano-sized grainy structures and hillocks above the surface of implanted PMMA. The FTIR spectra confirmed the modifications in chemical structure of PMMA along with the formation of -C=C- carbon contents. The refractive index, extinction coefficient and photoconductivity of implanted PMMA have been found to increase as a function of ion fluence. Simultaneously, indirect optical band gap is reduced from 3.13 to 0.81 eV at a relatively high fluence (5 x 10(15) ions/cm(2)). A linear correlation has been established between the band gap and Urbach energies. Moreover, the electrical conductivity of Ag+ implanted PMMA has increased from 2.14 x 10(-10) (pristine) to 9.6 x 10(-6) S/cm. (C) 2016 Elsevier B.V. All rights reserved.