Structural modification of carbon nanotube film toward multifunctional composites via a wet-compression method

Abstract

Carbon nanotube film (CNTF) assembled by floating catalyst chemical vapor deposition (FFCVD) is a promising material for smart textile, multifunctional composites and soft robotics due to their lightweight, flexibility and electromechanical properties. However, bulk CNTF exhibit unsatisfactory properties, due to the loose and porous packing structures. In this study, an innovative and effective strategy was proposed to densify CNTF by a compression in acetone (wet compression). Due to low surface tension, acetone is easy to penetrate the CNTF and act as a lubricant thus decrease the interactions between the neighboring carbon nanotubes (CNT) under load. Therefore, the CNTF was condensed in thickness from 11.3 to 8.4 µm (34.5% decrease) with a CNT volume fraction increment (~ 11% to ~ 14.7%) under wet-compression treatment. Consequently, the wet-compressed CNTF tensile strength, electrical conductivity and gauge factor enhanced by 97%, 34% and 43% along the direction of CNT alignment and by 213%, 42% and 101% towards the CNT transverse direction. As a potential application, modified CNTF/epoxy composites were fabricated as strong de-icing parts of an airplane. The tensile strength increased to 742 MPa (by 21%) and effectively melted ice by 250 times weight ratio within 1 min; performing as strengthened lightweight multifunctional materials. To summarize, our work provides a universal approach to enhance the overall mechanical properties of the CNTF for several applications.