Formation of Polymer-Carbon Nanotube Composites by Two-Step Supercritical Fluid Treatment

• Published in: Materials Vol. 14; no. 23; p. 7428
• Main Authors: Vorobei, Anton M., Ustinovich, Konstantin B., Chernyak, Sergei A., Savilov, Sergei V., Parenago, Olga O., Kiselev, Mikhail G.
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 03.12.2021; MDPI
• Subjects: Atmospheric pressure; Carbon dioxide; Chemical precipitation; CNT-polymer composites; Composite materials; Multi wall carbon nanotubes; Nanocomposites; Phase transitions; Polymer matrix composites; Polymers; Power; rapid expansion of supercritical suspensions (RESS); Solvents; supercritical antisolvent precipitation (SAS); Supercritical fluids; Tensile strength; Ultrasonic imaging; Russia
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma14237428

An approach for polymer-carbon nanotube (CNT) composite preparation is proposed based on a two-step supercritical fluid treatment. The first step, rapid expansion of a suspension (RESS) of CNTs in supercritical carbon dioxide, is used to de-bundle CNTs in order to simplify their mixing with polymer in solution. The ability of RESS pre-treatment to de-bundle CNTs and to cause significant bulk volume expansion is demonstrated. The second step is the formation of polymer-CNT composite from solution via supercritical antisolvent (SAS) precipitation. SAS treatment allows avoiding CNT agglomeration during transition from a solution into solid state due to the high speed of phase transition. The combination of these two supercritical fluid methods allowed obtaining a polycarbonate-multiwalled carbon nanotube composite with tensile strength two times higher compared to the initial polymer and enhanced elasticity.