Fabrication of cross-linked carbon nanotube foam using polymethylmethacrylate microspheres as templates

Abstract

Assembling carbon nanotubes (CNTs) into macroscopic and engineered structures with desired configuration and properties is the key step to realize their extensive applications. We devised a simple and scalable method to fabricate three-dimensional CNT foams using polymethylmethacrylate (PMMA) microspheres as templates and polyacrylonitrile (PAN) as a precursor to create crosslinks among CNTs. The porosity and the pore size of the CNT foam can be tuned easily by adjusting the concentration and particle size of the PMMA spheres. The assembled CNT foams have a hierarchically porous structure and the pore size ranges from several nanometers to tens of micrometers. The effect of PAN on crosslinking CNTs was evaluated by using ultrathin freestanding CNT sheets. The structural observations and mechanical property improvement demonstrate that the PAN polymer converts into graphitic structures and accumulates at the joints of CNTs after thermal treatment at 1000 °C, which strengthen CNT assembly.