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  • 1.
    Benselfelt, Tobias
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Henschen, Jonatan
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Pettersson, Torbjörn
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Polyelectrolyte multilayers on differently charged cellulose surfaces2016In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 251Article in journal (Other academic)
  • 2. Budarin, Vitaliy L
    et al.
    Clark, James H
    Henschen, Jonatan
    Farmer, Thomas J
    Macquarrie, Duncan J
    Mascal, Mark
    Nagaraja, Gundibasappa K
    Petchey, Tabitha H M
    Processed Lignin as a Byproduct of the Generation of 5-(Chloromethyl)furfural from Biomass: A Promising New Mesoporous Material.2015In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 8, no 24, p. 4172-9Article in journal (Refereed)
    Abstract [en]

    The lignin by-product of the conversion of lignocellulosic biomass to 5-(chloromethyl)furfural (CMF) has been characterised by thermogravimetric analysis, N2 physisorption porosimetry, attenuated internal reflectance IR spectroscopy, elemental analysis and solid-state NMR spectroscopy. The lignin (LCMF) has a moderate level of mesoporosity before thermal treatment and a surface area of 63 m(2)  g(-1) , which increases dramatically on pyrolysis at temperatures above 400 °C. An assessment of the functionality and textural properties of the material was achieved by analysing LCMF treated thermally over a range of pyrolysis temperatures. Samples were sulfonated to test their potential as heterogeneous acid catalysts in the esterification of levulinic acid. It was shown that unpyrolysed catalysts gave the highest ester yields of up to 93 %. To the best of our knowledge, this is the first example of mesoporous lignin with an appreciable surface area that is produced directly from a bio-refinery process and with further textural modification of the material demonstrated.

  • 3.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Li, Dongfang
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Henschen, Jonatan
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Esterification and hydrolysis of cellulose using oxalic acid dihydrate in a solvent-free reaction suitable for preparation of surface-functionalised cellulose nanocrystals with high yield2017In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 19, p. 5564-5567Article in journal (Refereed)
    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%

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  • 4.
    Henschen, Jonatan
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Bacterial adhesion to polyelectrolyte modified materials based on nanocellulose2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Since the introduction of materials based on cellulose nanofibrils (CNFs), these materials have been studied extensively and are suggested to be suitable for use in, for example, hygiene and health care products. A property not very well studied but that could further increase the usability of CNF products is the possibility of controlling bacterial adhesion to the materials. Controlling and fine-tuning the bacterial adhesion makes it possible to produce contact-active antibacterial materials as well as anti-adhesive materials.

    The current thesis shows how the number of bacteria adhering to CNF-based materials can be altered through the adsorption of polyelectrolyte multilayers. Polyvinylamine (PVAm) and polyacrylic acid (PAA) were adsorbed in multilayers to achieve differently charged materials. The CNF substrates consisted of both crosslinked and non-crosslinked films with different surface charges and structures as well as porous aerogels.

    The results show the possibility of adsorbing PVAm/PAA to recharge the surfaces and construct multilayers. The polyelectrolyte adsorption was affected both by crosslinking and by changing the surface charge of the CNF films. Increasing the surface charge resulted in a decreased PVAm adsorption after the first polymer layer. Crosslinking the films resulted in a low initial PVAm adsorption, but as more layers were adsorbed, the PVAm adsorption increased similarly to the non-crosslinked films. The PVAm adsorption to the aerogels was lower than expected, taking into account their high surface area and surface charge, possibly due to crowding effects on the surface due to geometric limitations.

    Only the CNF films with the lowest surface charge and the aerogels adsorbed high numbers of bacteria from bacterial suspensions. The bacterial adsorption to the films was affected by the surface charge, the PAA adsorption and the PVAm adsorption, with a higher net surface charge leading to higher bacterial adsorption. The aerogels efficiently removed bacteria from the bacterial suspensions by adsorbing them onto their surface, with some samples removing over 99.9 % of the bacteria. The results presented in this thesis are believed to lead to a better understanding of both polyelectrolyte adsorption on CNF materials and bacterial adhesion to CNF materials and how polyelectrolyte multilayer adsorption can alter it.

  • 5.
    Henschen, Jonatan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Bio-based preparation of nanocellulose and functionalization using polyelectrolytes2019Doctoral thesis, comprehensive summary (Other academic)
    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.

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  • 6.
    Henschen, Jonatan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Illergård, Josefin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Larsson, Per A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Contact-active antibacterial aerogels from cellulose nanofibrils2016In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 146, p. 415-422Article in journal (Refereed)
    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.

  • 7.
    Henschen, Jonatan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Illergård, Josefin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Larsson, Per
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Antibacterial aerogels from cellulose nanofibrils2016In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 251Article in journal (Other academic)
  • 8.
    Henschen, Jonatan
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Illergård, Josefin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Larsson, Per
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Ek, Monica
    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.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Antibacterial surface modification of nanocellulosic materials2015In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 249Article in journal (Other academic)
  • 9.
    Henschen, Jonatan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Larsson, Per A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Illergård, Josefin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Bacterial adhesion to polyvinyl-amine-modified nanocellulose filmsManuscript (preprint) (Other academic)
  • 10.
    Henschen, Jonatan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Larsson, Per A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Illergård, Josefin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Bacterial adhesion to polyvinylamine-modified nanocellulose films2017In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 151, p. 224-231Article in journal (Refereed)
    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.

  • 11.
    Henschen, Jonatan
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Li, Dongfang
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Ek, Monica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Preparation of cellulose nanomaterials via cellulose oxalates2019In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 213, p. 208-216Article in journal (Refereed)
    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.

  • 12.
    Larsson, Per
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Erlandsson, Johan
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    López Durán, Veronica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Henschen, Jonatan
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Tchang Cervin, Nicholas
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. Innventia AB, Stockholm, Sweden.
    Al-Ansari, Zeinab
    Univ Copenhagen, Dept Pharm, Copenhagen, Denmark..
    Svagan, Anna Justina
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Crosslinking as a facilitator for novel (nano)cellulose-based applications2017In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 253Article in journal (Other academic)
  • 13.
    Ottenhall, Anna
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Chen, Chao
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Henschen, Jonatan
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Illergård, Josefin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Larsson, Per A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Layer-by-layer modification of cellulosic materials for green antibacterial materials2017In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 253Article in journal (Other academic)
  • 14.
    Ottenhall, Anna
    et al.
    KTH, School of Chemical Science and Engineering (CHE).
    Henschen, Jonatan
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Illergård, Josefin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Bacteria adsorbing emergency water filters based on polyelectrolyte modified paperManuscript (preprint) (Other academic)
    Abstract [en]

    Water filtration is a popular way to remove particles and microorganisms from drinking water but is generally based on size exclusion of the particles. Bacteria can be modeled as small particles with a diameter of 1-2 µm, which is usually too small to be excluded by paper filters. In this article, commercial available paper filters have been surface modified by polyelectrolyte multilayer adsorption to create a positively charged filter that can trap the negatively charged bacteria through electrostatic interactions. The polyelectrolyte modified filters bind the bacteria to there surface and will thereby remove bacteria from the water instead of inactivated them through addition of biocides. The modified filters can remove more than 99.9 % of bacteria in water, depending on filter design, and has successfully been compared to a commercial cellulose water filter, based on the release of silver to inactivate bacteria. This cheap and easy modification of filter paper has potential to create disposable water purification filters that could be used in emergency situations to prevent outbreak of lethal diarrheal diseases.

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  • 15.
    Ottenhall, Anna
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Henschen, Jonatan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Illergård, Josefin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ek, Monica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Cellulose-based water purification using paper filters modified with polyelectrolyte multilayers to remove bacteria from water through electrostatic interactions2018In: Environmental Science: Water Research & Technology, ISSN 2053-1400Article in journal (Refereed)
    Abstract [en]

    Filtration is a common way to obtain pure drinking water by removing particles and microorganisms based on size exclusion. Cellulose-based filters are affordable and biobased option for the removal of particles but bacteria are usually too small to be removed by size exclusion alone. In this article, the surfaces of cellulose fibres in two types of commercial paper filters have been given a positive net charge to trap bacteria through electrostatic interactions without releasing any biocides. The fibres were modified with the cationic polyelectrolyte polyvinylamine polymer in single layers (1 L) or in multilayers together with the anionic polyelectrolyte polyacrylic acid (3 L or 5 L) using a water-based process at room temperature. Filtration tests show that all filters, using both types of filter papers and a number of layers, can physically remove more than 99.9% of E. coli from water and that the 3 L modified filters can remove more than 97% of cultivatable bacteria from natural water samples. The bacterial reduction increased with increasing number of filter sheets used for the filtration and the majority of the bacteria were trapped in the top sheets of the filter. The results show the potential for creating water purification filters from bio-based everyday consumable products with a simple modification process. The filters could be used in the future for point-of-use water purification that may be able to save lives without releasing bactericides.

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