Understanding the Dispersive Action of Nanocellulose for Carbon Nanomaterials.
This work aims at understanding the excellent ability of nanocelluloses to disperse carbon nanomaterials (CNs) in aqueous media to form long-term stable colloidal dispersions without the need for chemical functionalization of the CNs or the use of surfactant. These dispersions are useful for composites with high CN content when seeking water-based, efficient, and green pathways for their preparation. To establish a comprehensive understanding of such dispersion mechanism, colloidal characterization of the dispersions has been combined with surface adhesion measurements using colloidal probe atomic force microscopy (AFM) in aqueous media. AFM results based on model surfaces of graphene and nanocellulose further suggest that there is an association between the nanocellulose and the CN. This association is caused by fluctuations of the counterions on the surface of the nanocellulose inducing dipoles in the sp2carbon lattice surface of the CNs. Furthermore, the charges on the nanocellulose will induce an electrostatic stabilization of the nanocellulose-CN complexes that prevents aggregation. On the basis of this understanding, nanocelluloses with high surface charge density were used to disperse and stabilize carbon nanotubes (CNTs) and reduced graphene oxide particles in water, so that further increases in the dispersion limit of CNTs could be obtained. The dispersion limit reached the value of 75 wt % CNTs and resulted in high electrical conductivity (515 S/cm) and high modulus (14 GPa) of the CNT composite nanopapers.
Department of Fibre and Polymer Technology, Wallenberg Wood Science Centre, KTH Royal Institute of Technology , Teknikringen 56, 100 44, Stockholm, Sweden.
Alireza
0000-0003-0298-8553
A
Hajian
Division of Solid Mechanics, Department of Management and Engineering, Linköping University , SE-581 83 Linköping, Sweden.
Stefan B
0000-0002-1503-8293
SB
Lindström
Department of Fibre and Polymer Technology, Wallenberg Wood Science Centre, KTH Royal Institute of Technology , Teknikringen 56, 100 44, Stockholm, Sweden.
Torbjörn
0000-0002-5444-7276
T
Pettersson
Department of Fibre and Polymer Technology, Wallenberg Wood Science Centre, KTH Royal Institute of Technology , Teknikringen 56, 100 44, Stockholm, Sweden.
Mahiar M
0000-0001-9088-1064
MM
Hamedi
Department of Fibre and Polymer Technology, Wallenberg Wood Science Centre, KTH Royal Institute of Technology , Teknikringen 56, 100 44, Stockholm, Sweden.
Lars
0000-0001-8622-0386
L
Wågberg
Nanocellulose; carbon nanotubes; conductivity; counterions; graphene; interaction; surface charge