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Cellulose–Assisted Dispersion of Carbon Nanotubes: From Colloids to Composites
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH Royal Institute of Technology.ORCID iD: 0000-0003-0298-8553
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

It is a challenge to disperse nanoparticles to obtain a nanostructured composite. This thesis aims at providing a new route to fabricate carbon nanotube (CNT) composites and suggests mechanisms for nanocellulose–CNT interactions. This route is based on unmodified CNT dispersed in water with the help of nanocellulose. Chemical functionalization of the CNTs and the addition of surfactants are avoided. Thus, the mechanical and electrical properties of such nanotube composites can be improved.

Cellulose derivatives can disperse and stabilize carbon nanotubes in water. Nanocellulose particles, such as cellulose nanofibrils (CNF), are a new form of cellulose derivatives that are able to disperse and stabilize untreated carbon nanotubes in water. The utilization of the hybrid CNF–CNT dispersions are shown to lead to strong nanostructured composites with high nanotube content and conductivity. The mechanism behind the dispersive action of nanocellulose for nanotubes is explored and studied in detail. The dispersive ability of the nanocellulose leads to improved properties of CNF–CNT composites.

Apart from studies of structure and properties of composite fibers and films, two different functional materials are studied in detail. One is to form conductive patterns on cellulose nanopaper for the stable function of printed electronics in various environmental conditions and during handling. The second is to use a water-soluble cellulosic polymer–nanotube dispersion to fabricate superelastic aerogels without any chemical crosslinking or the addition of another component. This makes the aerogels easily recyclable (redispersible in water) and opens a new route for recyclable superelastic CNT composite aerogels.

Abstract [sv]

Det är en utmaning att dispergera nanopartiklar för nanostrukturerade kompositer. Avhandlingen beskriver en ny väg för att framställa kompositer från kolnanorör (CNT) och föreslår mekanismer för växelverkan mellan CNT och CNF. Den nya vägen baseras sig på dispergering av CNT i vatten med hjälp av CNF. CNT behöver inte modifieras kemiskt eller med ytaktiva ämnen. Mekaniska och elektriska egenskaper hos materialen kan därför förbättras.

Cellulsosaderivat kan dispergera och stabilisera CNT i vatten. Nanocellulosa är en ny typ av derivat, i form av fibriller eller nanokristaller, som kan dispergera och stabilisera icke modifierade CNT i vatten. Dispersioner av CNF-CNT används för att framställa starka nanokompositer med hög CNT-halt och hög elektrisk ledningsförmåga. Dispergerings-mekanismen studeras och förklaras från experimentella data. Den dispergerande förmågan hos CNF leder till förbättrade egenskaper hos CNF-CNT-kompositer.

Struktur-egenskaps relationer för fibrer och filmer rapporteras. Två typer av funktionella material studeras i detalj. Ett av materialen består av ledande mönster av CNF-CNT på substrat av nanocellulosa. Det andra exemplet är superelastiska aerogeler utan kemisk tvärbindning. Aerogelerna kan återvinnas och öppnar möjligheter för superelastiska aerogeler.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2018. , p. 55
Series
TRITA-CBH-FOU ; 2018:2
Keywords [en]
Nanocelluloses, Carbon nanotubes, Composites, Colloids
National Category
Composite Science and Engineering Paper, Pulp and Fiber Technology Nano Technology
Research subject
Fibre and Polymer Science
Identifiers
URN: urn:nbn:se:kth:diva-223453ISBN: 978-91-7729-685-0 (print)OAI: oai:DiVA.org:kth-223453DiVA, id: diva2:1184525
Public defence
2018-03-14, F3, Lindstedtsvägen 26, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20180221

Available from: 2018-02-21 Created: 2018-02-21 Last updated: 2018-03-09Bibliographically approved
List of papers
1. Highly Conducting, Strong Nanocomposites Based on Nanocellulose-Assisted Aqueous Dispersions of Single-Wall Carbon Nanotubes
Open this publication in new window or tab >>Highly Conducting, Strong Nanocomposites Based on Nanocellulose-Assisted Aqueous Dispersions of Single-Wall Carbon Nanotubes
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2014 (English)In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 8, no 3, p. 2467-2476Article in journal (Refereed) Published
Abstract [en]

It is challenging to obtain high-quality dispersions of single-wall nanotubes (SWNTs) in composite matrix materials, in order to reach the full potential of mechanical and electronic properties. The most widely used matrix materials are polymers, and the route to achieving high quality dispersions of SWNT is mainly chemical functionalization of the SWNT. This leads to increased cost, a loss of strength and lower conductivity. In addition full potential of colloidal self-assembly cannot be fully exploited in a polymer matrix. This may limit the possibilities for assembly of highly ordered structural nanocomposites. Here we show that nanofibrillated cellulose (NFC) can act as an excellent aqueous dispersion agent for as-prepared SWNTs, making possible low-cost exfoliation and purification of SWNTs with dispersion limits exceeding 40 wt %. The NFC:SWNT dispersion may also offer a cheap and sustainable alternative for molecular self-assembly of advanced composites. We demonstrate semitransparent conductive films, aerogels and anisotropic microscale fibers with nanoscale composite structure. The NFC:SWNT nanopaper shows increased strength at 3 wt % SWNT, reaching a modulus of 133 GPa, and a strength of 307 MPa. The anisotropic microfiber composites have maximum conductivities above 200 S cm(-1) and current densities reaching 1400 A cm(-2).

Keywords
nanocellulose, nanopaper, carbon nanotubes, dispersions, composites, conductivity, self-assembly
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:kth:diva-144950 (URN)10.1021/nn4060368 (DOI)000333539400059 ()2-s2.0-84896929193 (Scopus ID)
Funder
Knut and Alice Wallenberg Foundation
Note

QC 20140505

Available from: 2014-05-05 Created: 2014-05-05 Last updated: 2018-02-21Bibliographically approved
2. Understanding the Dispersive Action of Nanocellulose for Carbon Nanomaterials
Open this publication in new window or tab >>Understanding the Dispersive Action of Nanocellulose for Carbon Nanomaterials
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2017 (English)In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 17, no 3, p. 1439-1447Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2017
Keywords
nanocellulose, carbon nanotubes, graphene, interaction, surface charge, conductivity, counterions
National Category
Nano Technology Physical Chemistry Materials Chemistry Paper, Pulp and Fiber Technology Composite Science and Engineering
Identifiers
urn:nbn:se:kth:diva-203930 (URN)10.1021/acs.nanolett.6b04405 (DOI)000396185800018 ()2-s2.0-85014970890 (Scopus ID)
Funder
Knut and Alice Wallenberg Foundation
Note

QC 20170327

Available from: 2017-03-20 Created: 2017-03-20 Last updated: 2018-02-21Bibliographically approved
3. Cellulose nanofibers enable paraffin encapsulation and the formation of stable thermal regulation nanocomposites
Open this publication in new window or tab >>Cellulose nanofibers enable paraffin encapsulation and the formation of stable thermal regulation nanocomposites
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2017 (English)In: Nano Energy, ISSN 2211-2855, Vol. 34, p. 541-548Article in journal (Refereed) Published
Abstract [en]

Non-leaking, green materials with high content of phase change materials (PCM) can conserve solar energy and contribute to a sustainable society. Here, paraffin was encapsulated by nanocellulose (CNF) through a pickering emulsion method, while simultaneously forming a composite material. The thermodynamic drive for phase separation was confirmed by molecular modeling. Particle formation was characterized by dynamic light scattering and they were processed into stable PCM/CNF composites in the form of PCM paper structures with favorable mechanical properties. The PCM composite was lightweight and showed a solid content of paraffin of more than 72 wt%. Morphology was characterized using FE-SEM. The thermal regulation function of the PCM composite was demonstrated in the form of a model roof under simulated sunlight. No obvious leakage was observed during heating/cooling cycles, as supported by DSC and SAXS data. The PCM composite can be extended to panels used in energy-efficient smart buildings with thermal regulation integrated in load-bearing structures.

Keywords
Nanocellulose, Phase change materials, Encapsulation, Thermal regulation, Biocomposites
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-204014 (URN)10.1016/j.nanoen.2017.03.010 (DOI)000400383300057 ()2-s2.0-85015399594 (Scopus ID)
Funder
Knut and Alice Wallenberg Foundation
Note

QC 20170411

Available from: 2017-03-22 Created: 2017-03-22 Last updated: 2018-02-21Bibliographically approved
4. Recyclable and superelastic aerogels based on carbon nanotubes and carboxymethyl cellulose
Open this publication in new window or tab >>Recyclable and superelastic aerogels based on carbon nanotubes and carboxymethyl cellulose
2018 (English)In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 159, p. 1-10Article in journal (Refereed) Published
Abstract [en]

Deformation mechanisms are largely unknown for superelastic carbon nanotube (CNT) aerogels, and this hampers materials design efforts. The CNT network in the cell walls is typically crosslinked or connected by a thermoset polymer phase. In order to create a recyclable superelastic aerogel, unmodified single or multi-walled CNTs were dispersed in water by adding to aqueous carboxymethyl cellulose (CMC) solution. Directional freeze-drying was used to form honeycombs with cell walls of random-in-the-plane CNTs in CMC matrix. Cell wall morphology and porosity were studied and related to CNT type and content, as well as elastic or plastic buckling of the cell walls under deformation. CMC acts as a physical crosslinker for the CNTs in a porous cell wall. Aerogel structure and properties were characterized before and after recycling. The conductivity of the composite aerogel with a density of 10 kg/m3, 99% porosity and 50 wt % single-walled CNT exceeds 0.5 S/cm. The potential of these superelastic and conductive aerogels for applications such as mechanoresponsive materials was examined in cyclic conductivity tests at different strains. This opens a new route for recyclable superelastic CNT composite aerogels, avoiding material loss, chemical treatment or addition of other components.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Polymers; Nanocomposites; CNT networks; Conductivity; Recycle
National Category
Composite Science and Engineering Textile, Rubber and Polymeric Materials Nano Technology
Research subject
Materials Science and Engineering
Identifiers
urn:nbn:se:kth:diva-223432 (URN)10.1016/j.compscitech.2018.01.002 (DOI)000436214100001 ()2-s2.0-85042350204 (Scopus ID)
Note

QC 20180308

Available from: 2018-02-21 Created: 2018-02-21 Last updated: 2018-07-17Bibliographically approved

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