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Strong and Flexible Nanocomposites of Carboxylated Cellulose Nanofibril Dispersed by Industrial Lignin
Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Wallenberg Wood Science Center, Sweden.
2018 (English)In: ACS Sustainable Chemistry & Engineering, ISSN 2168-0485, Vol. 6, no 4, p. 5524-5532Article in journal (Refereed) Published
Abstract [en]

We demonstrated that industrial lignin can be facilely processed with carboxylated cellulose nanofibril (CNF) to obtain strong, flexible, and transparent nanocomposites via film casting of dispersions. The tensile strength and strain to failure of lignin–CNF nanocomposites (245 MPa and 15%, respectively at 7.7 wt % of lignin) are superior to previously reported polymer/nanoparticle–CNF composites with polymer contents below 50 wt %, such as poly(vinyl alcohol)–CNF films and even reduced graphene oxide–CNF films. The excellent mechanical properties of lignin–CNF nanocomposite films are related to the lignin-enhanced colloidal stability and dispersity of CNF in aqueous dispersions supported by measurements of rheology and dynamic light scattering, which accordingly suppresses the excess fibril aggregates during film formation. Moreover, lignin in the nanocomposites benefits an efficient functionalization of gold/iron oxide nanoparticles on the surface of nanocomposites. This study illustrates the great potential of industrial lignin in developing nanocellulose-based materials with advanced properties and functionalities.

Place, publisher, year, edition, pages
2018. Vol. 6, no 4, p. 5524-5532
Keyword [en]
flexibility, high strength, lignin, multifunctionalities, nanocellulose
National Category
Chemical Sciences
Research subject
Materials Chemistry
Identifiers
URN: urn:nbn:se:su:diva-155263DOI: 10.1021/acssuschemeng.8b00402ISI: 000429285800118OAI: oai:DiVA.org:su-155263DiVA, id: diva2:1198273
Available from: 2018-04-17 Created: 2018-04-17 Last updated: 2018-04-30Bibliographically approved
In thesis
1. Nanocellulose-based materials: from colloidal assembly to functional films
Open this publication in new window or tab >>Nanocellulose-based materials: from colloidal assembly to functional films
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The assembly of nature-based nanomaterials into complex architectures is both a design principle of biological composites, e.g., wood and nacre with outstanding properties and a promising route for developing functional macroscopic materials. This thesis aims to investigate and understand the colloidal and self-assembly behaviour of nanocellulose in aqueous dispersions. Moreover, composite films of nanocellulose and nanoclay/lignin with diverse functionalities, e.g., mechanical and optical properties, are fabricated by tailoring the electrostatic interactions of these building blocks.

The evaporation induced assembly of sulfonated cellulose nanocrystal (CNC) has been followed in either an aqueous droplet on substrates or a levitated droplet by real-time small angle X-ray scattering. The evolution of structural features, e.g., an isotropic phase, biphasic phase, fully liquid crystalline and contracted helical structures of drying CNC dispersions were related to the power-law scaling of the particle separation distance (d) with concentrations (c, from 1 vol% to 38 vol%). Below 2 vol%, CNC dispersions consolidated isotropically with a scaling of d c-1/3, while the fully cholesteric liquid crystalline phase showed a unidimensional contraction of the nematic structure (d c-1) with increasing concentrations. Competition between gelation and the ordered assembly of CNC was quantitatively evaluated in nanoscale for the first time, which was reflected by a scaling of d c-2/3.

The rheology of composite dispersions of carboxylated cellulose nanofibril (CNF) and nanoclay was investigated, which was influenced by the surface charge of CNF, the morphology of nanoclays and interactions between CNF and clay particles. Optically transparent films of synthetic aminoclay (50 wt%) and CNF were fabricated, of which tensile strength and strain to failure (205 MPa and 7.5%) were significantly higher than those of nacre and other nacre-mimicking nanocellulose-based materials, e.g., montmorillonite-CNF films, due to the formation of ionic bonding between the cationic clay and anionic CNF.

Lignin nanoparticles were testified to enhance the colloidal stability and dispersity of carboxylated CNF in dispersions, and showed a remarkable strengthening and stiffening effect on the matrix of CNF. The mechanical properties of lignin-CNF films were superior to previously reported polymer/nanoparticle-CNF composites, such as polyvinyl alcohol-CNF films and even reduced graphene oxide-CNF films.

Place, publisher, year, edition, pages
Stockholm: Department of Materials and Environmental Chemistry, Stockholm University, 2018. p. 63
National Category
Materials Chemistry
Research subject
Materials Chemistry
Identifiers
urn:nbn:se:su:diva-155267 (URN)978-91-7797-248-8 (ISBN)978-91-7797-249-5 (ISBN)
Public defence
2018-06-07, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 2: Manuscript.

Available from: 2018-05-15 Created: 2018-04-17 Last updated: 2018-05-09Bibliographically approved

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