Electrically conductive nanocomposites of PMMA and carbon nanotubes prepared by in situ polymerization under probe sonication

Carbon nanotubes (CNT) have superior mechanical, electrical and thermal properties that can be incorporated into polymeric matrices for applications in optoelectronic devices, antistatic coatings, electromagnetic shielding materials, and so on. Yet, to transfer their properties to the matrix they must be well dispersed. This work proposes the synthesis of conductive nanocomposites based on polymethyl methacrylate (PMMA)/multiwalled carbon nanotubes (MWCNT) by in situ solution polymerization under probe sonication. The effect of CNT amounts and ultrasound amplitude on the electrical and thermal properties of the nanocomposites were studied by a factorial experimental design. Casting films presented electrical conductivity of 10 S/m at 2.2 wt% of MWCNT. TEM analyses showed that nanoparticles are interconnected and disperse without orientation. The degradation temperature of the nanocomposites increased about 15 °C. FTIR analyses of nanocomposites showed a new peak (1620 cm−1) due to a C–C bond between PMMA and CNT. Raman spectra presented a slight shift of the D and G′ bands towards higher wavenumbers for CNT after purification and nanocomposites. This could be related to some disentanglement of the nanotube bundles.