Improving photoluminescence, optical and electrical characteristics of PMMA films with gamma irradiation

Abstract

Polymeric materials are macromolecules, essentially a combination of numerous repeated subunits. Polymers are innovative and advanced materials that currently have a strong impact on our daily lives. In recent years, polymer use has been prominent due to the materials’ distinctive properties; thus, they entered different fields of science, technology and industrial-biomedical applications.The improvement of photoluminescence, optical and electrical characteristics of non-conducting Poly(methyl methacrylate) (PMMA) films was studied. Upon gamma irradiation of various doses, the photophysical and electrical properties of PMMA films were investigated using photoluminescence spectroscopy, ultraviolet–visible (UV-Vis) spectroscopy and the LCR Meter Bridge Circuit technique. The fluorescent response improved the photoluminescence (PL) spectral emission peaks according to gamma values. Strong fluorescence peaks appeared with the highest gamma dose. The UV–Vis results revealed a significant red-shift in the absorption edge as gamma doses increased. This shift exhibits a continuous decrease in the energy band gap values (from 3.50 to 2.60 eV for direct transition and from 3.05 to 1.55 eV for indirect transition). This was due to the formation of carbon clusters, which led to an increase in the electrical conductivity and improved the dielectric parameters of the irradiated PMMA films. Among a variety of measurements presented and discussed in the present study, the electrical measurements showed improved electrical characteristics of gamma-irradiated PMMA films.

Assessment the exposure effects of polycarbonate with X-ray radiation using spectroscopic techniques and molecular modeling calculations

“…The experimentally and theoretical FTIR spectra registered of polycarbonate structure are depicted in Fig. (4).…”

“…Three distinct processes are involved in luminescence: (a) excitons, or electron-hole (e-h) pairs, are excited by an external energy source; (b) the e-h pairs are thermalized toward thermal or epithermal equilibrium, and (c) the thermalized pairs undergo radiative recombination to generate electromagnetic emission. The recombination of excitons or band-to-defect level or band-toband transitions is commonly associated with peaks in the photoluminescence spectrum [4,15]. The radiative-recombination of the thermalized pairs of electron-hole (e-h) occurs in this technique as a result of the excitation and transfer of energy into the chromophoric sites [14].…”

“…Modifying the characteristics of polymeric materials has been done using different techniques, like chemical treatments, annealing temperatures, doping with suitable nanoparticles, and irradiation facilities [2][3][4]. Lately, the irradiation technique is an advanced tool employed to prepare and modify promising polymers that have unique physicochemical characteristics [5].…”

Synthesis, structural, optical, and thermal properties of LaFeO3/Poly(methyl methacrylate)/Poly(vinyl acetate) nanocomposites for radiation shielding

“…Poly(methyl methacrylate), PMMA, also known as acrylic, is a stiff polymer that exhibits interesting hardness, optical clarity, and abrasion resistance. As a result, it is used a lot in micro-photonics, optical lenses and devices, solar cells instead of glass, dosimetry, alpha particle detection, and as a base for nanofillers to block gamma-rays and UV light 9 . Cao et al 1 reported that the PMMA mixed with 15.6–44 wt% Bi 2 O 3 particles showed good blocking γ-rays with energies up to 1 MeV.…”