Towards large scale aligned carbon nanotubes based composite production

International audienceWhile the production capacity of dispersed carbon nanotubes is booming, the coming industrial production of vertically aligned carbon nanotubes (VACNTs) carpets/arrays/forests is still at its first stages.. The main challenge is the control of carbon nanotube characteristics in terms of length, density, cleanness, diameter and structure through a low cost process applicable, in only one-step, to large surfaces and under safe conditions. We present the main results obtained within the framework of the French program NaWaA4, which aims at demonstrating the feasibility of high surface (> A4 format size) fabrication of composite embedding vertically aligned carbon nanotubes in organic matrixes. Two applications were targeted: hybrid composites (single or multilayer) and single thin film for membranes. In this study we will focus on the scaling-up of the aerosol assisted CCVD process, which allows to grow, through a one-step process, uniform and well aligned CNT carpets on flat and flexible substrates at high throughput. The different routes investigated to functionalise through partial coating or grafting of carpets or to totally impregnate carpets with different polymers in order to fabricate nanocomposite materials will be presented. A special attention has been paid to the preservation of the alignment during all these processes, the removal of the substrate, and composite thinning and surface cleaning in order to control the surface and to open the nanotubes tips especially for membrane applications. We present also an original X-ray diffraction system that has been developed to control the quality of the alignment, cleanliness and thickness all along the process. Results regarding electrical, mechanical and permeability properties will also be detailed, which demonstrate the industrial feasibility of the production of VACNTs based composites for many applications from mechanical reinforced composites to multifunctional electrodes or membranes