Synthesis of semiconductors nanocomposites of polymethyl methacrylate and reduced graphene oxide by ultraviolet radiation

Polymeric nanocomposites of polymethylmethacrylate (PMMA) added with up to 20wt.% of graphene oxide (GO) were synthesized by the solvent evaporation technique and, for the first time, irradiated with ultraviolet radiation (UV-B) to reduce GO and obtain novel films of electrically semiconductive nanocomposites (PMMA-rGO). The exposition times to reduce the GO in these nanocomposites were 48 and 96 h. Chemical, physical, and electrical conductivity analyses were performed, and both GO and rGO added PMMA nanocomposites results were compared before and after UV-B radiation. Plain PMMA results were also compared as control. These results showed that the addition of GO flakes and its reduction (rGO) by UV-B radiation promoted better thermal stability and stiffness to the nanocomposites than to plain PMMA, as demonstrated by the thermogravimetric and differential scanning calorimetry analyses. High resolution scanning electron microscopy demonstrated well distributed rGO particles in the PMMA matrix. FTIR and Raman confirm the reduction process of GO after being UV-B rays irradiated. The colorimetric analyses showed that the GO and rGO flakes and the PMMA matrix presented an excellent superficial interaction. The results of electrical conductivity for the PMMA matrix (4.50 × 10−9 S/m) and the nanocomposites with 2 wt. % GO (1.21 × 10−9 S/m) revealed an insulating behavior, whcich decreases for an addition of 20 wt.% GO. The electrical conductivity displayed a significant improvement with UV-B radiation, such that with 20 wt.% rGO exposed to 48 and 96 h of UV-B radiation, the PMMA-rGO nanocomposites became semiconductor.