title: Layer-by-layer assembled films of multi-walled carbon nanotubes with chitosan and cellulose nanocrystals.
abstract: Chitosan solutions and cellulose nanocrystal suspensions were used to produce highly stable aqueous dispersions of multi-walled carbon nanotubes (MWCNTs). The different MWCNT dispersions, presenting positive and negative charges, were used to prepare multilayered hybrid thin films through electrostatic layer-by-layer (LBL) self-assembly. The MWCNTs are well dispersed and homogeneously distributed on each layer of chitosan and cellulose nanocrystals of the films. The nanotubes are densely packed in each multilayer, forming a random network. The surface of the LBL film exhibited a uniform and relatively smooth surface with a mean roughness value of ∼5.8±0.4nm. Electrochemical characterization revealed a decrease in two orders of magnitude in the film resistance as the number of bilayers increased from 5 to 20, which is a consequence of an increase in the amount of conductive material (MWCNT). The thin films with up to 20 bilayers exhibited transmittance higher than 90% in the visible range. The results presented in this work demonstrate the viability of the LBL technique for the deposition of active materials using the biopolymer pair chitosan/cellulose nanocrystals. The obtained films can be employed for the design of transparent and biocompatible carbon nanostructured based electrodes.
authors.affiliation: Departamento de Química, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627 - Pampulha, CEP 31270-901 Belo Horizonte, MG, Brazil. Electronic address: joaopcampos@yahoo.com.br.
authors.forename: João Paulo Campos
authors.initials: JP
authors.lastname: Trigueiro
authors.affiliation: Departamento de Química, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627 - Pampulha, CEP 31270-901 Belo Horizonte, MG, Brazil. Electronic address: glaurasilva@yahoo.com.
authors.forename: Glaura Goulart
authors.initials: GG
authors.lastname: Silva
authors.affiliation: Departamento de Química, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627 - Pampulha, CEP 31270-901 Belo Horizonte, MG, Brazil. Electronic address: fabianovargas@yahoo.com.
authors.forename: Fabiano Vargas
authors.initials: FV
authors.lastname: Pereira
authors.affiliation: Departamento de Química, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627 - Pampulha, CEP 31270-901 Belo Horizonte, MG, Brazil. Electronic address: rodrigo.lavall@qui.ufmg.br.
authors.forename: Rodrigo Lassarote
authors.initials: RL
authors.lastname: Lavall
keywords: Cellulose nanocrystals; Chitosan; Highly stable dispersions; Layer-by-layer assembly; Multi-walled carbon nanotubes; Multilayers films