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Bio-based preparation of nanocellulose and functionalization using polyelectrolytes
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. (Wood Chemistry and Pulp Technology)ORCID iD: 0000-0001-6263-8403
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [sv]

Nanocellulosa, som kan utvinnas från skogsråvara, har de senaste åren fått mycket uppmärksamhet för sina intressanta egenskaper och breda användningsområde. Studierna i denna avhandling syftar till att vidga möjligheterna att använda nanocellulosa i olika applikationer. Detta har skett genom att utveckla en ny metod för att tillverka nanocellulosa och genom att studera möjligheten att adsorbera polyelektrolyter på material av nanocellulosa för att ändra hur bakterier interagerar med dessa.

Nanocellulosan tillverkades genom att förbehandla pappersmassa med smält oxalsyra dihydrat. Reaktionsblandningen tvättades med etanol, aceton eller tetrahydrofuran innan den torkades och fibrillerades. Den resulterande nanocellulosan erhölls med högt utbyte, hade hög ytladdning (upp till 1,4 mmol g-1) och innehöll partiklar som både liknande nanofibriller och nanokristaller. Materialet visades kunna användas både för att tillverka Pickering emulsioner och tunna filmer med en styrka upp till 197 MPa, töjning upp till 5 %, E-modul upp till 10,6 GPa och syrepermeabilitet ner till 0.31 cm3 µm m‑2 dag‑kPa‑1.

Genom att adsorbera polyvinylamin och polyakrylsyra på material av nanocellulosa visades det vara möjligt att påverka mängden bakterier som fäster till materialet. Substraten bestod både av kompakta filmer och porösa aerogeler. Genom att variera ytladdningen på materialen, ytans struktur och antalet adsorberade lager av polymererna var det möjligt att tillverka material med både hög och låg bakterieadhesion. Detta gör det möjligt att anpassa material för användning antingen som kontaktaktivt- eller icke-adhesivt antibakteriellt material. Båda dessa kan vara miljövänliga alternativ till dagens antibakteriella material.

Nanocellulosa är ett material som inom snar framtid sannolikt kommer användas inom en mängd olika applikationer. För att öka mängden applikationer där nanocellulosa tillför ett stort värde är det nödvändigt att utveckla alternativa tillverkningsmetoder till dagens välkända, exempelvis, genom att använda den beskrivna oxaleringen som förbehandling. Förmågan att styra bakterieadhesionen på material av nanocellulosa ger därtill möjlighet att hitta nya användningsområden inom t.ex. hälso- och sjukvårdsbranschen.

Abstract [en]

Nanocellulose is a material which can be extracted from wood, and in recent years it has received great attention for its interesting properties and wide range of possible applications. With the aim of further expanding the applications of nanocellulose, this work has studied a new way to produce nanocellulose as well as the possibility of using polyelectrolyte adsorption to alter the interaction with bacteria of materials made from nanocellulose.

Nanocellulose was produced by a novel concurrent esterification and hydrolysis of wood pulp in molten oxalic acid dihydrate. The resulting mixture was washed using ethanol, acetone or tetrahydrofuran before the cellulose oxalate was dried and fibrillated. The nanocellulose obtained with a high yield had a high surface charge (up to 1.4 mmol g-1) and contained particles with a morphology similar to both cellulose nanocrystals and cellulose nanofibrils. The material was used to prepare both Pickering emulsions and thin films with a strength of up to 197 MPa, a strain at break of up to 5 %, a modulus of up to 10.6 GPa and an oxygen permeability as low as 0.31 cm3 µm m-2 day-1 kPa-1.

Polyelectrolyte adsorption of polyvinylamine and polyacrylic acid was used to modify materials made from nanocellulose. Materials in the form of films and aerogels were used as substrates. By altering the surface charge of the material, the surface structure and the number of layers of polyvinylamine/polyacrylic acid adsorbed, it was possible to prepare materials with both high and low bacterial adhesion. By changing the material properties it is possible to tailor materials with either contact-active or non-adhesive antibacterial properties, both of which are sustainable alternatives to the currently used antibacterial materials.

Nanocellulose is a material which in the near future will probably be used in many applications. In order to improve the suitability of nanocellulose in certain applications it will be necessary to use production methods which differ from the existing methods, for example by using oxalation as a pre-treatment. By modifying the bacterial adhesion to materials prepared from nanocellulose, new medical and health applications emerge.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2019. , p. 67
Series
TRITA-CBH-FOU ; 2019:36
Keywords [en]
cellulose nanofibrils, cellulose nanocrystals, oxalic acid, polyvinylamine, layer by layer, cellulose oxalate, antibacterial
Keywords [sv]
Cellulosa nanofibriller, cellulosa nanokristaller, oxalsyra, polyvinylamin, lager på lager, cellulosa oxalat, antibakteriell
National Category
Paper, Pulp and Fiber Technology
Research subject
Fibre and Polymer Science
Identifiers
URN: urn:nbn:se:kth:diva-252580ISBN: 978-91-7873-245-6 (print)OAI: oai:DiVA.org:kth-252580DiVA, id: diva2:1319562
Public defence
2019-08-30, F3, Lindstedtsvägen 26, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 2019-06-05

Available from: 2019-06-05 Created: 2019-06-02 Last updated: 2019-06-05Bibliographically approved
List of papers
1. Esterification and hydrolysis of cellulose using oxalic acid dihydrate in a solvent-free reaction suitable for preparation of surface-functionalised cellulose nanocrystals with high yield
Open this publication in new window or tab >>Esterification and hydrolysis of cellulose using oxalic acid dihydrate in a solvent-free reaction suitable for preparation of surface-functionalised cellulose nanocrystals with high yield
2017 (English)In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 19, p. 5564-5567Article in journal (Refereed) Published
Abstract [en]

A one-pot esterification and hydrolysis of cellulose was carried outby treating cellulose fibres with molten oxalic acid dihydrate. Eachcellulose oxalate had a free carboxyl content above 1.2 mmol g−1and an average molecular weight of approximately 40 kDa.Aqueous suspensions of the oxalates were sonicated to preparecellulose nanocrystals with a gravimetric yield of 80.6%

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2017
National Category
Paper, Pulp and Fiber Technology
Research subject
Chemistry
Identifiers
urn:nbn:se:kth:diva-219967 (URN)10.1039/c7gc02489d (DOI)000417758700005 ()2-s2.0-85035811625 (Scopus ID)
Note

QC 20171218

Available from: 2017-12-14 Created: 2017-12-14 Last updated: 2019-06-05Bibliographically approved
2. Preparation of cellulose nanomaterials via cellulose oxalates
Open this publication in new window or tab >>Preparation of cellulose nanomaterials via cellulose oxalates
2019 (English)In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 213, p. 208-216Article in journal (Refereed) Published
Abstract [en]

Nanocellulose prepared from cellulose oxalate has been discussed as an alternative to other methods to prepare cellulose nanofibrils or crystals. The current work describes the use of a bulk reaction between pulp and oxalic acid dihydrate to prepare cellulose oxalate followed by homogenization to produce nanocellulose. The prepared nanocellulose is on average 350 nm long and 3–4 nm wide, with particles of size and shape similar to both cellulose nanofibrils and cellulose nanocrystals. Films prepared from this nanocellulose have a maximum tensile stress of 140–200 MPa, strain at break between 3% and 5%, and oxygen permeability in the range of 0.3–0.5 cm 3 μm m −2 day −1 kPa −1 at 50% relative humidity. The presented results illustrate that cellulose oxalates may be a low-cost method to prepare nanocellulose with properties reminiscent of those of both cellulose nanofibrils and cellulose nanocrystals, which may open up new application areas for cellulose nanomaterials.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Cellulose, Cellulose nanocrystals, Cellulose nanofibrils, Cellulose oxalate, Nanocellulose, Oxalic acid dihydrate
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-246408 (URN)10.1016/j.carbpol.2019.02.056 (DOI)000461316200023 ()30879662 (PubMedID)2-s2.0-85062349488 (Scopus ID)
Note

QC 20190401

Available from: 2019-04-01 Created: 2019-04-01 Last updated: 2019-06-02Bibliographically approved
3. Bacterial adhesion to polyvinylamine-modified nanocellulose films
Open this publication in new window or tab >>Bacterial adhesion to polyvinylamine-modified nanocellulose films
Show others...
2017 (English)In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 151, p. 224-231Article in journal (Refereed) Published
Abstract [en]

Cellulose nanofibril (CNF) materials have been widely studied in recent years and are suggested for a wide range of applications, e.g., medical and hygiene products. One property not very well studied is the interaction between bacteria and these materials and how this can be controlled. The current work studies how bacteria adhere to different CNF materials modified with polyelectrolyte multilayers. The tested materials were TEMPO-oxidized to have different surface charges, periodate-oxidized to vary the water interaction and hot-pressed to alter the surface structure. Then, multilayers were constructed using polyvinylamine (PVAm) and polyacrylic acid. Both the material surface charge and water interaction affect the amount of polymer adsorbed to the surfaces. Increasing the surface charge decreases the adsorption after the first PVAm layer, possibly due to conformational changes. Periodate-oxidized and crosslinked films have low initial polymer adsorptions; the decreased swelling prevents polymer diffusion into the CNF micropore structure. Microscopic analysis after incubating the samples with bacterial suspensions show that only the materials with the lowest surface charge enable bacteria to adhere to the surface because, when adsorbing up to 5 layers PVAm/PAA, the increased anionic surface charge appears to decrease the net surface charge. Both the amounts of PVAm and PAA influence the net surface charge and thus the bacterial adhesion. The structure generated by the hot-pressing of the films also strongly increases the number of bacteria adhering to the surfaces. These results indicate that the bacterial adhesion to CNF materials can be tailored using polyelectrolyte multilayers on different CNF substrates.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Bacterial adhesion, Cellulose nanofibrils, Polyelectrolyte multilayers, Polymer adsorption, Polyvinylamine
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-200877 (URN)10.1016/j.colsurfb.2016.12.018 (DOI)000394475400027 ()2-s2.0-85006856296 (Scopus ID)
Note

QC 20170203

Available from: 2017-02-03 Created: 2017-02-03 Last updated: 2019-06-02Bibliographically approved
4. Contact-active antibacterial aerogels from cellulose nanofibrils
Open this publication in new window or tab >>Contact-active antibacterial aerogels from cellulose nanofibrils
Show others...
2016 (English)In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 146, p. 415-422Article in journal (Refereed) Published
Abstract [en]

The use of cellulose aerogels as antibacterial materials has been investigated by applying a contact-active layer-by-layer modification to the aerogel surface. Studying the adsorption of multilayers of polyvinylamine (PVAm) and polyacrylic acid to aerogels comprising crosslinked cellulose nanofibrils and monitoring the subsequent bacterial adhesion revealed that up to 26 mg PVAm g aerogel−1 was adsorbed without noticeably affecting the aerogel structure. The antibacterial effect was tested by measuring the reduction of viable bacteria in solution when the aerogels were present. The results show that >99.9% of the bacteria adhered to the surface of the aerogels. Microscopy further showed adherence of bacteria to the surfaces of the modified aerogels. These results indicate that it is possible to create materials with three-dimensional cellulose structures that adsorb bacteria with very high efficiency utilizing the high specific surface area of the aerogels in combination with their open structure.

Keywords
Antibacterial, Cellulose nanofibrils, Aerogel, Contact active, Polymer adsorption
National Category
Paper, Pulp and Fiber Technology
Research subject
Materials Science and Engineering
Identifiers
urn:nbn:se:kth:diva-185001 (URN)10.1016/j.colsurfb.2016.06.031 (DOI)000382269600046 ()2-s2.0-84977269377 (Scopus ID)
Funder
VINNOVA
Note

QC 20160825

Available from: 2016-04-07 Created: 2016-04-07 Last updated: 2019-06-02Bibliographically approved

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