The synergy of ultrasonic treatment and organic modifiers for tuning the surface chemistry and conductivity of multiwalled carbon nanotubes

摘要

Multiwalled carbon nanotubes (CNT) were modified via the non-covalent approach using anodic surfactants dodecylbenzenesulfonic acid (DBSA) and poly(ethylene glycol) n-alkyl 3-sulfopropyl ether potassium salt and cationic surfactant cetyltrimethylammonium bromide (CTAB). These surfactants were used individually or as DBSA/CTAB mixtures. Surface modification was ultrasonically-assisted with a control over sonication power (64 or 360 W). The surface properties of modified CNT particles were determined by X-ray photoelectron spectroscopy and scanning electron microscopy. The electrical conductivities of unmodified CNT, particles treated by ultrasound, and CNT modified with surfactants were measured. Thermogravimetric analysis was used to determine the mass loading of surfactants after drying. The highest increase in conductivity was reached when CNT were treated solely with the anionic surfactant DBSA under the influence of soft ultrasound. This work shows conclusively that ultrasound-assisted modification of CNT by surfactants is a simple and efficient approach to prepare surface modified and highly conductive CNT, provided that physical (ultrasonic) and chemical (surfactants) treatments are concomitantly controlled.