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Surface modification approaches of cellulose nanofibrils and their effect on dispersibility
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.ORCID iD: 0000-0002-3906-4381
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In the strive to find and develop sustainable bio-based materials an increased interest for nanocellulosic materials as attractive alternatives has arisen during the past decades. This can be attributed to their abundant renewability, remarkable inherent mechanical properties and their capability to be chemically modified. Cellulose nanofibrils (CNFs) are commonly obtained from wood pulp fibres and prepared through mechanical, chemical and/or enzymatic treatments. However, due to their hydrophilic nature and tendency to self-aggregate, their surface chemistry need to be altered to fully utilise their inherent properties and enable their usage in conventional large-scale industrial processes.

This thesis work focuses on elucidating the fundamental aspects of the colloidal stability of highly concentrated CNF dispersions and the redispersibility of dried CNFs. Small amounts of amine-terminated poly(ethylene glycol) (PEG) were used to sterically stabilise the CNFs at higher fibril concentrations and delay the dispersion-arrested state transition (Paper I). The redispersibility of dried CNFs was studied for differently charged CNFs as a function of redispersing agents such as carboxymethyl cellulose (CMC), PEG and lignin (Paper II).

This thesis presents green, facile modification approaches as well as strategies for improved dispersibility and compatibility with polymer matrices. The commercially established carboxymethylation process was expanded with a subsequent functionality step, yielding a mild, versatile one-pot protocol for the preparation of bi-functional CNFs (Paper III). Further, reactive amphiphilic macromolecules with targeted side-chain functionalities were used to compatibilise the CNF surface by water-based approaches. In the first study, a macroinitiator was used for the development of a versatile, yet facile, protocol for the controlled polymerisation of both hydrophilic and hydrophobic monomers in water from the CNF surface (Paper IV). In the second study, a reactive macro-compatibiliser was used to molecularly engineer the interface between CNFs and a polymer matrix by reactive-melt processing, yielding nanocomposites with improved stiffness while maintaining the deformability (Paper V).

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2019. , p. 60
Series
TRITA-CBH-FOU ; 2019:12
Keywords [en]
cellulose nanofibrils, colloidal stability, re/dispersibility, surface modification, bio-nanocomposites, interface
Keywords [sv]
cellulosa nanofibriller, kolloidal stabilitet, re/dispergerbarhet, ytmodifiering, bio-nanokompositer, gränssnitt
National Category
Polymer Technologies Paper, Pulp and Fiber Technology
Research subject
Fibre and Polymer Science
Identifiers
URN: urn:nbn:se:kth:diva-244070ISBN: 978-91-7873-093-3 (print)OAI: oai:DiVA.org:kth-244070DiVA, id: diva2:1289316
Public defence
2019-03-22, F3, Lindstedtsvägen 26, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20190221

Available from: 2019-02-22 Created: 2019-02-17 Last updated: 2019-02-25Bibliographically approved
List of papers
1. Insights into the EDC-mediated PEGylation of cellulose nanofibrils and their colloidal stability
Open this publication in new window or tab >>Insights into the EDC-mediated PEGylation of cellulose nanofibrils and their colloidal stability
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2018 (English)In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 181, p. 871-878Article in journal (Refereed) Published
Abstract [en]

EDC-mediated coupling has frequently been utilized to poly(ethylene glycol) functionalize (PEGylate) cellulose-based materials, but no work has previously been reported on the direct N-(3-dimethylaminopropyl)-N-ethylcarbodiimide (EDC)-mediated PEGylation of cellulose nanofibrils (CNF). Herein, we report the first study where CNF has been directly sterically stabilized with amine-terminated PEG employing N-hydroxysuccinimide (NHS)-assisted EDC-coupling. This work has shown that this coupling reaction is highly sensitive to the reaction conditions and purification procedures, and hence an optimized coupling protocol was developed in order to achieve a reaction yield. Elemental analysis of the nitrogen content also showed the successful PEGylation. It was also shown that a surprisingly low PEGylation (1%) is sufficient to significantly improve the colloidal stability of the PEGylated samples, which reached dispersion-arrested-state-transitions at higher concentrations than neat CNF. The colloidal stability was preserved with increasing ionic strength, when comparably long polymer chains were grafted, targeting only 1% PEGylation.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Cellulose nanofibrils, Colloidal stability, PEGylation, Steric stabilization
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-220410 (URN)10.1016/j.carbpol.2017.11.065 (DOI)000418661000101 ()29254048 (PubMedID)2-s2.0-85037689178 (Scopus ID)
Note

QC 20171220

Available from: 2017-12-20 Created: 2017-12-20 Last updated: 2019-02-17Bibliographically approved
2. Redispersibility properties of dried cellulose nanofibrils - influence on structure and mechanical properties
Open this publication in new window or tab >>Redispersibility properties of dried cellulose nanofibrils - influence on structure and mechanical properties
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2019 (English)In: Article in journal (Other academic) Epub ahead of print
National Category
Polymer Technologies Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-244055 (URN)
Note

QC 20190218

Available from: 2019-02-15 Created: 2019-02-15 Last updated: 2019-02-18Bibliographically approved
3. One-pot preparation of bi-functional cellulose nanofibrils
Open this publication in new window or tab >>One-pot preparation of bi-functional cellulose nanofibrils
2018 (English)In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, no 12, p. 7031-7042Article in journal (Refereed) Published
Abstract [en]

Herein, we present a route to obtain bi-functional cellulose nanofibrils (CNF) by a one-pot approach using an already established functionalisation route, carboxymethylation, to which a subsequent functionalisation step, allylation or alkynation, has been added in the same reaction pot, eliminating the need of solvent exchange procedures. The total charge of the fibres and the total surface charge of the nanofibrils were determined by conductometric and polyelectrolyte titration, respectively. Furthermore, the allyl and alkyne functionalised cellulose were reacted with methyl 3-mercaptopropionate and azide-functionalised disperse red, respectively, to estimate the degree of functionalisation. The samples were further assessed by XPS and FT-IR. Physical characteristics were evaluated by CP/MAS C-13-NMR, XRD, AFM and DLS. This new approach of obtaining bi-functionalised CNF allows for a facile and rapid functionalisation of CNF where chemical handles can easily be attached and used for further modification of the fibrils.

Place, publisher, year, edition, pages
SPRINGER, 2018
Keywords
Carboxymethylation, Functionalised cellulose nanofibrils, Allylation, Alkynation
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-239754 (URN)10.1007/s10570-018-2066-y (DOI)000449946300016 ()2-s2.0-85054565647 (Scopus ID)
Note

QC 20190110

Available from: 2019-01-10 Created: 2019-01-10 Last updated: 2019-02-17Bibliographically approved
4. All-aqueous SI-ARGET ATRP from cellulose nanofibrils using hydrophilic and hydrophobic monomers
Open this publication in new window or tab >>All-aqueous SI-ARGET ATRP from cellulose nanofibrils using hydrophilic and hydrophobic monomers
2019 (English)In: Article in journal (Other academic) Submitted
National Category
Polymer Technologies Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-244057 (URN)
Note

QC 201902

Available from: 2019-02-15 Created: 2019-02-15 Last updated: 2019-02-18Bibliographically approved
5. Molecular engineering of cellulose-PCL bio-nanocomposite interface by reactive amphiphilic copolymer nanoparticles
Open this publication in new window or tab >>Molecular engineering of cellulose-PCL bio-nanocomposite interface by reactive amphiphilic copolymer nanoparticles
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2019 (English)In: Article in journal (Refereed) Accepted
National Category
Polymer Technologies Paper, Pulp and Fiber Technology Composite Science and Engineering
Identifiers
urn:nbn:se:kth:diva-244058 (URN)
Note

QC 20190218

Available from: 2019-02-15 Created: 2019-02-15 Last updated: 2019-02-18Bibliographically approved

Open Access in DiVA

The full text will be freely available from 2020-02-22 11:00
Available from 2020-02-22 11:00

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Kaldéus, Tahani

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