Ultra-stiff large-area carpets of carbon nanotubes

Abstract

Herewith, we report the influence of post-synthesis heat treatment (≤2350 °C and plasma temperatures) on the crystal structure, defect density, purity, alignment and dispersibility of free-standing large-area (several cm(2)) carpets of ultra-long (several mm) vertically aligned multi-wall carbon nanotubes (VA-MWCNTs). VA-MWCNTs were produced in large quantities (20-30 g per batch) using a semi-scaled-up aerosol-assisted chemical vapour deposition (AACVD) setup. Electron and X-ray diffraction showed that the heat treatment at 2350 °C under inert atmosphere purifies, removes residual catalyst particles, and partially aligns adjacent single crystals (crystallites) in polycrystalline MWCNTs. The purification and improvement in the crystallites alignment within the MWCNTs resulted in reduced dispersibility of the VA-MWCNTs in liquid media. High-resolution microscopy revealed that the crystallinity is improved in scales of few tens of nanometres while the point defects remain largely unaffected. The heat treatment also had a marked benefit on the mechanical properties of the carpets. For the first time, we report compression moduli as high as 120 MPa for VA-MWCNT carpets, i.e. an order of magnitude higher than previously reported figures. The application of higher temperatures (arc-discharge plasma, ≥4000 °C) resulted in the formation of a novel graphite-matrix composite reinforced with CVD and arc-discharge-like carbon nanotubes.

Conductive single-wall carbon nanotubes/extracellular matrix hybrid hydrogels promote the lineage-specific development of seeding cells for tissue repair through reconstructing an integrin-dependent niche

“…In previous reports, SWCNTs were frequently selected to modify scaffolds for cardiac or neural application [ 31 , 37 – 41 ]; and (3) Mechanical property. SWCNTs are of higher tensile strength and elastic modulus, more suitable for soft tissue scaffolds; while MWCNTs have higher rigidity, more suitable for stiff tissue scaffolds, such as bone [ 42 , 43 ]. In fact, MWCNTs were often incorporated into composite scaffolds to promote osteogenesis [ 44 – 46 ].…”