Synthesis, characterization and thermal properties of PMMA/CuO polymeric nanocomposites

Abstract

The CuO nanoparticles (NPs) were prepared by the reaction of Cu(NO3)2·3H2O with caustic soda followed by calcination of the obtained precipitate at 400 °C for 4 h. The surface of as-prepared CuO NPs was then modified by oleic acid in order to act as a good dispersibility of NPs with organic media. Surface modification of CuO NPs was confirmed through lipophilic degree (LD). The results revealed that LD increased with the rising amount of oleic acid up to 9 wt%. Optimum modification was obtained at 65 °C and 5 h for reaction time. The modified NPs were dispersed in methyl methacrylate (MMA) monomer, and PMMA/CuO polymeric nanocomposites (PNCs) were synthesized via in situ emulsion polymerization. The CuO NPs, modified NPs and PMMA/CuO PNCs were characterized by XRD, FT-IR, SEM, EDX and XPS spectra. The average crystallite sizes of CuO NPs and modified CuO NPs that are calculated from XRD diffraction are 45 and 60 nm respectively. The morphological observation revealed that CuO NPs were embedded homogeneously in the inner part of PMMA. In addition, the particles are distributed better and more uniformly (monodisperse) in the PNCs. Two peaks observed at about 933.8 and 953.8 eV in XPS spectra are corresponded to Cu2p3/2 and Cu2p1/2 of Cu2+ in CuO NPs respectively. The thermal stability of PMMA/CuO PNCs was studied using TGA and DSC techniques. The prepared PMMA/CuO PNCs have glass transition temperature up to 22 °C and thermal degradation temperature up to 60 °C higher than PMMA. The photo-catalytic activity of CuO NPs, modified NPs and PMMA/CuO PNCs was investigated in the degradation of methyl orange (MO) under UV radiation. The PDP of methyl orange took place by 80% for 8 h in the presence of CuO NPs, while it dropped by 55 and 30% in the presence of CuO NPs modified by stearic acid and grafted by PMMA respectively. The results showed that PDP of MO solution by CuO NPs decreases when modified using oleic acid and/or grafted on PMMA.