Phosphonium–based ionic liquid as dispersing agent for MWCNT in melt-mixing polystyrene blends: Rheology, electrical properties and EMI shielding effectiveness

• Published in: Materials chemistry and physics Vol. 189; pp. 162 - 168
• Main Authors: Soares da Silva, Jéssica P., Soares, Bluma G., Livi, Sebastien, Barra, Guilherme M.O.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01-03-2017; Elsevier BV; Elsevier
• Subjects: Carbon; Chemical Sciences; Dispersion; Electric properties; Electrical conductivity; Electrical properties; Electrical resistivity; Electromagnetic interference; Electromagnetic shielding; Ionic liquids; Material chemistry; Multi wall carbon nanotubes; Multi-walled carbon nanotube; Nanocomposites; Nanotubes; Polymer blends; Polymers; Polystyrene; Polystyrene resins; Raman spectroscopy; Rheological properties; Rheology; Room temperature ionic liquid; Thermogravimetric analysis; Transmission electron microscopy; Electrical conductivity; Nanocomposites; Polystyrene; Room temperature ionic liquid; Multi-walled carbon nanotube
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2016.12.073

Conducting nanocomposites composed with polystyrene (PS) and multi-walled carbon nanotubes (MWCNT) were prepared by melt mixing procedure assisted by trihexyl-(tetradecyl)-phosphonium combined with bis(trifluoromethylsulfonyl) amide counteranion (TFSI) as the ionic liquid (IL). The non-covalent functionalization of MWCNT with the IL was confirmed by Raman spectroscopy and thermogravimetric analysis. The functionalized MWCNT provided better dispersion of the MWCNT within PS matrix, as indicated by transmission electron microscopy (TEM), and also an electrical conductivity as high as 10−1 S/m with 0.66 m% of MWCNT combined with 3.34 m% of IL. This value is around four orders of magnitude higher when compared to nanocomposites with similar amount of untreated MWCNT. From rheological studies, it was observed that the transition between liquid-like to solid-like behavior occurred at lower frequencies for the systems containing functionalized MWCNT. Moreover, an improvement of around 170% in the electromagnetic interference shielding effectiveness (EMI SE) in the X-band frequency range was observed for the nanocomposites containing 1% of MWCNT non-covalently functionalized with the IL, that is, 1% of MWCNT and 5% of IL.
•MWCNT well dispersed in PS matrix, in the presence of ionic liquid.•Outstanding electric conductivity of PS/MWCNT nanocomposite.•Improved EMI shielding effectiveness by addition of ionic liquid in PS/MWCNT nanocomposite.