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Publications (10 of 42) Show all publications
Karlsson, R.-M. P., Larsson, P. T., Yu, S., Pendergraph, S. A., Pettersson, T., Hellwig, J. & Wågberg, L. (2018). Carbohydrate gel beads as model probes for quantifying non-ionic and ionic contributions behind the swelling of delignified plant fibers. Journal of Colloid and Interface Science, 519, 119-129
Open this publication in new window or tab >>Carbohydrate gel beads as model probes for quantifying non-ionic and ionic contributions behind the swelling of delignified plant fibers
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2018 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 519, p. 119-129Article in journal (Refereed) Published
Abstract [en]

Macroscopic beads of water-based gels consisting of uncharged and partially charged beta-(1,4)-D-glucan polymers were developed to be used as a novel model material for studying the water induced swelling of the delignified plant fiber walls. The gel beads were prepared by drop-wise precipitation of solutions of dissolving grade fibers carboxymethylated to different degrees. The internal structure was analyzed using Solid State Cross-Polarization Magic Angle Spinning Carbon-13 Nuclear Magnetic Resonance and Small Angle X-ray Scattering showing that the internal structure could be considered a homogeneous, non-crystalline and molecularly dispersed polymer network. When beads with different charge densities were equilibrated with aqueous solutions of different ionic strengths and/or pH, the change in water uptake followed the trends expected for weak polyelectrolyte gels and the trends found for cellulose-rich fibers. When dried and subsequently immersed in water the beads also showed an irreversible loss of swelling depending on the charge and type of counter-ion which is commonly also found for cellulose-rich fibers. Taken all these results together it is clear that the model cellulose-based beads constitute an excellent tool for studying the fundamentals of swelling of cellulose rich plant fibers, aiding in the elucidation of the different molecular and supramolecular contributions to the swelling.

Place, publisher, year, edition, pages
Academic Press, 2018
Keywords
Swelling, Water uptake, Hydrogel, Cellulose, Small-angle X-ray scattering, Solid state NMR, Atomic force microscopy
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-226733 (URN)10.1016/j.jcis.2018.02.052 (DOI)000429633500013 ()29486431 (PubMedID)2-s2.0-85042413398 (Scopus ID)
Funder
Knut and Alice Wallenberg Foundation
Note

QC 20180503

Available from: 2018-05-03 Created: 2018-05-03 Last updated: 2018-05-03Bibliographically approved
Mittal, N., Ansari, F., Gowda, K. V., Brouzet, C., Chen, P., Larsson, P. T., . . . Söderberg, D. (2018). Multiscale Control of Nanocellulose Assembly: Transferring Remarkable Nanoscale Fibril Mechanics to Macroscale Fibers. ACS Nano, 12(7), 6378-6388
Open this publication in new window or tab >>Multiscale Control of Nanocellulose Assembly: Transferring Remarkable Nanoscale Fibril Mechanics to Macroscale Fibers
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2018 (English)In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 12, no 7, p. 6378-6388Article in journal (Refereed) Published
Abstract [en]

Nanoscale building blocks of many materials exhibit extraordinary mechanical properties due to their defect-free molecular structure. Translation of these high mechanical properties to macroscopic materials represents a difficult materials engineering challenge due to the necessity to organize these building blocks into multiscale patterns and mitigate defects emerging at larger scales. Cellulose nanofibrils (CNFs), the most abundant structural element in living systems, has impressively high strength and stiffness, but natural or artificial cellulose composites are 3-15 times weaker than the CNFs. Here, we report the flow-assisted organization of CNFs into macroscale fibers with nearly perfect unidirectional alignment. Efficient stress transfer from macroscale to individual CNF due to cross-linking and high degree of order enables their Young's modulus to reach up to 86 GPa and a tensile strength of 1.57 GPa, exceeding the mechanical properties of known natural or synthetic biopolymeric materials. The specific strength of our CNF fibers engineered at multiscale also exceeds that of metals, alloys, and glass fibers, enhancing the potential of sustainable lightweight high-performance materials with multiscale self-organization.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
Keywords
bio-based materials, selforganization, mechanical properties, microfluidics, cellulose nanofibrils, nanocompositesbio-based materials, selforganization, mechanical properties, microfluidics, cellulose nanofibrils, nanocomposites
National Category
Engineering and Technology
Research subject
Engineering Mechanics; Fibre and Polymer Science; Physics
Identifiers
urn:nbn:se:kth:diva-229288 (URN)10.1021/acsnano.8b01084 (DOI)000440505000004 ()29741364 (PubMedID)2-s2.0-85049865626 (Scopus ID)
Funder
Knut and Alice Wallenberg Foundation
Note

QC 20180608

Available from: 2018-06-01 Created: 2018-06-01 Last updated: 2019-02-07Bibliographically approved
Kaldéus, T., Larsson, P. T., Boujemaoui, A. & Malmström, E. (2018). One-pot preparation of bi-functional cellulose nanofibrils. Cellulose (London), 25(12), 7031-7042
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
Lo Re, G., Spinella, S., Boujemaoui, A., Vilaseca, F., Larsson, P. T., Adås, F. & Berglund, L. (2018). Poly(ε-caprolactone) Biocomposites Based on Acetylated Cellulose Fibers and Wet Compounding for Improved Mechanical Performance. ACS Sustainable Chemistry & Engineering, 5(6), 6753-6760
Open this publication in new window or tab >>Poly(ε-caprolactone) Biocomposites Based on Acetylated Cellulose Fibers and Wet Compounding for Improved Mechanical Performance
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2018 (English)In: ACS Sustainable Chemistry & Engineering, ISSN 2168-0485, Vol. 5, no 6, p. 6753-6760Article in journal, Editorial material (Refereed) Published
Abstract [en]

Poly(epsilon-caprolactone) (PCL) is a ductile thermoplastic, which is biodegradable in the marine environment. Limitations include low strength, petroleum-based origin, and comparably high cost. Cellulose fiber reinforcement is therefore of interest although uniform fiber dispersion is a challenge. In this study, a one-step wet compounding is proposed to validate a sustainable and feasible method to improve the dispersion of the cellulose fibers in hydrophobic polymer matrix as PCL, which showed to be insensitive to the presence of the water during the processing. A comparison between unmodified and acetylated cellulosic wood fibers is made to further assess the net effect of the wet feeding and chemical modification on the biocomposites properties, and the influence of acetylation on fiber structure is reported (ATR-FTIR, XRD). Effects of processing on nano fibrillation, shortening, and dispersion of the cellulose fibers are assessed as well as on PCL molar mass. Mechanical testing, dynamic mechanical thermal analysis, FE-SEM, and X-ray tomography is used to characterize composites. With the addition of 20 wt % cellulosic fibers, the Young's modulus increased from 240 MPa (neat PCL) to 1850 MPa for the biocomposites produced by using the wet feeding strategy, compared to 690 MPa showed for the biocomposites produced using dry feeling. A wet feeding of acetylated cellulosic fibers allowed even a greater increase, with an additional 46% and 248% increase of the ultimate strength and Young's modulus, when compared to wet feeding of the unmodified pulp, respectively.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
National Category
Polymer Technologies
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-225425 (URN)10.1021/acssuschemeng.8b00551 (DOI)000431927500117 ()2-s2.0-85046751578 (Scopus ID)
Note

QC 20180531

Available from: 2018-04-04 Created: 2018-04-04 Last updated: 2018-06-04Bibliographically approved
Larsson, P. T., Karlsson, R.-M. P., Westlund, P.-O. & Wågberg, L. (2017). Internal Structure of Isolated Cellulose I Fibril Aggregates in the Water Swollen State. In: Agarwal, UP Atalla, RH Isogai, A (Ed.), Nanocelluloses: Their Preparation, Properties, and Applications. Paper presented at Anselme Payen Award Symposium in honor of Akira Isogai on Nanocelluloses, their Preparation, Properties and Applications / Spring ACS National Meeting, Mar 13-17, 2016, San Diego, CA (pp. 91-112). American Chemical Society (ACS), 1251
Open this publication in new window or tab >>Internal Structure of Isolated Cellulose I Fibril Aggregates in the Water Swollen State
2017 (English)In: Nanocelluloses: Their Preparation, Properties, and Applications / [ed] Agarwal, UP Atalla, RH Isogai, A, American Chemical Society (ACS), 2017, Vol. 1251, p. 91-112Conference paper (Refereed)
Abstract [en]

By combining H-2-NMRD and CP/MAS C-13-NMR measurements of water-based cellulose gels and of water swollen pulps it was possible to estimate the nature of the interior structure of cellulose fibril aggregates. A set of samples with high cellulose purity and low charge was used. The interpretation of data was based on a relaxation model describing the exchange dynamics for deuterium exchange between water molecules and cellulose hydroxyl groups. The theoretical model used made it possible to calculate cellulose surface-to-volume ratios (q-values) from both H-2-NMRD and CP/MAS C-13-NMR data. Good consistency between H-2-NMRD and CP/MAS C-13-NMR data was found. In all investigated samples the cellulose fibril aggregates showed a different degree of "openness" interpreted as the presence of interstitial water inside fibril aggregates. One result also showed that an increased degree of fibril aggregate openness results from the TEMPO-oxidation. Common to all samples was that in the water swollen state water molecules could access part of the fibril aggregate interior.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2017
Series
ACS Symposium Series, ISSN 0097-6156 ; 1251
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-220871 (URN)000417770800005 ()978-0-8412-3218-1 (ISBN)
Conference
Anselme Payen Award Symposium in honor of Akira Isogai on Nanocelluloses, their Preparation, Properties and Applications / Spring ACS National Meeting, Mar 13-17, 2016, San Diego, CA
Funder
Swedish Research CouncilKnut and Alice Wallenberg Foundation
Note

QC 20180108

Available from: 2018-01-08 Created: 2018-01-08 Last updated: 2018-01-08Bibliographically approved
Larsson, P. T., Wågberg, L., Westlund, P.-O. & Karlsson, P. (2016). Internal structure of cellulose I fibril aggregates studied by a combination of structure and dynamics measurements. Abstract of Papers of the American Chemical Society, 251
Open this publication in new window or tab >>Internal structure of cellulose I fibril aggregates studied by a combination of structure and dynamics measurements
2016 (English)In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 251Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2016
National Category
Organic Chemistry
Identifiers
urn:nbn:se:kth:diva-242692 (URN)000431903802426 ()
Note

QC 20190221

Available from: 2019-02-21 Created: 2019-02-21 Last updated: 2019-02-21Bibliographically approved
Peciulyte, A., Karlström, K., Larsson, P. T. & Olsson, L. (2015). Impact of the supramolecular structure of cellulose on the efficiency of enzymatic hydrolysis. Biotechnology for Biofuels, 8, Article ID 56.
Open this publication in new window or tab >>Impact of the supramolecular structure of cellulose on the efficiency of enzymatic hydrolysis
2015 (English)In: Biotechnology for Biofuels, ISSN 1754-6834, E-ISSN 1754-6834, Vol. 8, article id 56Article in journal (Refereed) Published
Abstract [en]

Background: The efficiency of enzymatic hydrolysis is reduced by the structural properties of cellulose. Although efforts have been made to explain the mechanism of enzymatic hydrolysis of cellulose by considering the interaction of cellulolytic enzymes with cellulose or the changes in the structure of cellulose during enzymatic hydrolysis, the process of cellulose hydrolysis is not yet fully understood. We have analysed the characteristics of the complex supramolecular structure of cellulose on the nanometre scale in terms of the spatial distribution of fibrils and fibril aggregates, the accessible surface area and the crystallinity during enzymatic hydrolysis. Influence of the porosity of the substrates and the hydrolysability was also investigated. All cellulosic substrates used in this study contained more than 96% cellulose. Results: Conversion yields of six cellulosic substrates were as follows, in descending order: nano-crystalline cellulose produced from never-dried soda pulp (NCC-OPHS-ND) > never-dried soda pulp (OPHS-ND) > dried soda pulp (OPHS-D) > Avicel > cotton treated with sodium hydroxide (cotton + NaOH) > cotton. Conclusions: No significant correlations were observed between the yield of conversion and supramolecular characteristics, such as specific surface area (SSA) and lateral fibril dimensions (LFD). A strong correlation was found between the average pore size of the starting material and the enzymatic conversion yield. The degree of crystallinity was maintained during enzymatic hydrolysis of the cellulosic substrates, contradicting previous explanations of the increasing crystallinity of cellulose during enzymatic hydrolysis. Both acid and enzymatic hydrolysis can increase the LFD, but no plausible mechanisms could be identified. The sample with the highest initial degree of crystallinity, NCC-OPHS-ND, exhibited the highest conversion yield, but this was not accompanied by any change in LFD, indicating that the hydrolysis mechanism is not based on lateral erosion.

Keywords
Cellulose I, Enzymatic hydrolysis, Cellulose supramolecular structure, Solid-state cross-polarization magic angle spinning carbon-13 nuclear magnetic resonance (CP/MAS C-13-NMR), Porosity, Crystallinity
National Category
Microbiology
Identifiers
urn:nbn:se:kth:diva-166491 (URN)10.1186/s13068-015-0236-9 (DOI)000352683600001 ()25870653 (PubMedID)2-s2.0-84927641545 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20150518

Available from: 2015-05-18 Created: 2015-05-11 Last updated: 2017-12-04Bibliographically approved
Sjöstedt, A., Wohlert, J., Larsson, P. T. & Wågberg, L. (2015). Structural changes during swelling of highly charged cellulose fibres. Cellulose (London), 22(5), 2943-2953
Open this publication in new window or tab >>Structural changes during swelling of highly charged cellulose fibres
2015 (English)In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, no 5, p. 2943-2953Article in journal (Refereed) Published
Abstract [en]

Structural changes of fibrils and fibril aggregates in the fibre wall were studied after oxidation of the cellulose by 2,2,6,6-tetramethyl-1-piperidinyloxy to high charge densities (highest charge density: 1300 mu eq/g). The increase in pore volume was measured by mini-WRV at two different pH levels, and the supramolecular structure in the fibre wall in terms of aggregate size, specific surface area and average pore size was measured by solid state NMR, DVS desorption and BET N-2 gas adsorption. A structural change in the arrangement of the fibrils inside the fibril aggregates was observed although the oxidation did not lead to a complete liberation of individual fibrils, i.e. they still exist as an aggregated structure after oxidation. Theoretical estimates suggest that the electrostatic repulsion energy connected with the increase in surface charge of the fibrils can be sufficient to gradually separate the fibrils enough to expose all fibril surfaces to oxidation chemicals.

National Category
Polymer Technologies Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-155537 (URN)10.1007/s10570-015-0701-4 (DOI)000361002000007 ()2-s2.0-84941416963 (Scopus ID)
Note

Updated from manuscript to article.

QC 20151009

Available from: 2014-11-07 Created: 2014-11-07 Last updated: 2017-12-05Bibliographically approved
Carlsson, L., Ingverud, T., Blomberg, H., Carlmark, A., Larsson, P. T. & Malmström, E. (2015). Surface characteristics of cellulose nanoparticles grafted by surface-initiated ring-opening polymerization of epsilon-caprolactone. Cellulose (London), 22(2), 1063-1074
Open this publication in new window or tab >>Surface characteristics of cellulose nanoparticles grafted by surface-initiated ring-opening polymerization of epsilon-caprolactone
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2015 (English)In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, no 2, p. 1063-1074Article in journal (Refereed) Published
Abstract [en]

In this study, surface-initiated ring-opening polymerization has been employed for the grafting of epsilon-caprolactone from cellulose nanoparticles, made by partial hydrolysis of cellulose cotton linters. A sacrificial initiator was employed during the grafting reactions, to form free polymer in parallel to the grafting reaction. The degree of polymerization of the polymer grafts, and of the free polymer, was varied by varying the reaction time. The aim of this study was to estimate the cellulose nanoparticle degree of surface substitution at different reaction times. This was accomplished by combining measurement results from spectroscopy and chromatography. The prepared cellulose nanoparticles were shown to have 3.1 (+/- 0.3) % of the total anhydroglucose unit content present at the cellulose nanoparticle surfaces. This effectively limits the amount of cellulose that can be targeted by the SI-ROP reactions. For a certain SI-ROP reaction time, it was assumed that the resulting degree of polymerization (DP) of the grafts and the DP of the free polymer were equal. Based on this assumption it was shown that the cellulose nanoparticle surface degree of substitution remained approximately constant (3-7 %) and seemingly independent of SI-ROP reaction time. We believe this work to be an important step towards a deeper understanding of the processes and properties controlling SI-ROP reactions occurring at cellulose surfaces.

Keywords
Solid-state cross-polarization magic angle spinning carbon-13 nuclear magnetic resonance (CP/MAS C-13-NMR), Surface grafting, Ring-opening polymerization, Degree of substitution, Cotton linters, Cellulose
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-163946 (URN)10.1007/s10570-014-0510-1 (DOI)000350876300010 ()2-s2.0-84925536313 (Scopus ID)
Funder
Swedish Research CouncilSwedish Research Council Formas
Note

QC 20150507

Available from: 2015-05-07 Created: 2015-04-13 Last updated: 2017-12-04Bibliographically approved
Carrick, C., Lindström, S. B., Larsson, P. T. & Wågberg, L. (2014). Lightweight, Highly Compressible, Noncrystalline Cellulose Capsules. Langmuir, 30(26), 7635-7644
Open this publication in new window or tab >>Lightweight, Highly Compressible, Noncrystalline Cellulose Capsules
2014 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 30, no 26, p. 7635-7644Article in journal (Refereed) Published
Abstract [en]

We demonstrate how to prepare extraordinarily deformable, gas-filled, spherical capsules from nonmodified cellulose. These capsules have a low nominal density, ranging from 7.6 to 14.2 kg/m(3), and can be deformed elastically to 70% deformation at 50% relative humidity. No compressive strain-at-break could be detected for these dry cellulose capsules, since they did not rupture even when compressed into a disk with pockets of highly compressed air. A quantitative constitutive model for the large deformation compression of these capsules is derived, including their high-frequency mechanical response and their low-frequency force relaxation, where the latter is governed by the gas barrier properties of the dry capsule. Mechanical testing corroborated these models with good accuracy. Force relaxation measurements at a constant compression rendered an estimate for the gas permeability of air through the capsule wall, calculated to 0.4 mL mu m/m(2) days kPa at 50% relative humidity. These properties taken together open up a large application area for the capsules, and they could most likely be used for applications in compressible, lightweight materials and also constitute excellent model materials for adsorption and adhesion studies.

Keywords
Stability, Microbubbles, Dissolution, Behavior, Shells, Foams
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:kth:diva-148607 (URN)10.1021/la501118b (DOI)000338806500003 ()2-s2.0-84903974299 (Scopus ID)
Note

QC 20140812

Available from: 2014-08-12 Created: 2014-08-11 Last updated: 2017-12-05Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-9176-7116

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