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Costa, C., Mira, I., Benjamins, J.-W., Lindman, B., Edlund, H. & Norgren, M. (2019). Interfacial activity and emulsion stabilization of dissolved cellulose. Journal of Molecular Liquids, 292, Article ID 111325.
Open this publication in new window or tab >>Interfacial activity and emulsion stabilization of dissolved cellulose
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2019 (English)In: Journal of Molecular Liquids, ISSN 0167-7322, E-ISSN 1873-3166, Vol. 292, article id 111325Article in journal (Refereed) Published
Abstract [en]

Some aspects of the interfacial behavior of cellulose dissolved in an aqueous solvent were investigated. Cellulose was found to significantly decrease the interfacial tension (IFT) between paraffin oil and 85 wt% phosphoric acid aqueous solutions. This decrease was similar in magnitude to that displayed by non-ionic cellulose derivatives. Cellulose's interfacial activity indicated a significant amphiphilic character and that the interfacial activity of cellulose derivatives is not only related to the derivatization but inherent in the cellulose backbone. This finding suggests that cellulose would have the ability of stabilizing dispersions, like oil-in-water emulsions in a similar way as a large number of cellulose derivatives. In its molecularly dissolved state, cellulose proved to be able to stabilize emulsions of paraffin in the polar solvent on a short-term. However, long-term stability against drop-coalescence was possible to achieve by a slight change in the amphiphilicity of cellulose, effected by a slight increase in pH. These emulsions exhibited excellent stability against coalescence/oiling-off over a period of one year. Ageing of the cellulose solution before emulsification (resulting in molecular weight reduction) was found to favour the creation of smaller droplets. 

Keywords
Adsorption, Amphiphilicity, Cellulose molecules, Emulsions, Interfacial activity, Oil-water interface
National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-36838 (URN)10.1016/j.molliq.2019.111325 (DOI)2-s2.0-85069688256 (Scopus ID)
Note

Available under a Creative Commons license https://creativecommons.org/licenses/by/4.0/

Available from: 2019-08-13 Created: 2019-08-13 Last updated: 2019-08-13Bibliographically approved
Medronho, B., Filipe, A., Costa, C., Romano, A., Lindman, B., Edlund, H. & Norgren, M. (2018). Microrheology of novel cellulose stabilized oil-in-water emulsions. Journal of Colloid and Interface Science, 531(1 December 2018), 225-232
Open this publication in new window or tab >>Microrheology of novel cellulose stabilized oil-in-water emulsions
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2018 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 531, no 1 December 2018, p. 225-232Article in journal (Refereed) Published
Abstract [en]

Diffusing wave spectroscopy (DWS) is a powerful optical technique suitable to investigate turbid samples in a nondestructive and reproducible way, providing information on the static and dynamic properties of the system. This includes the relative displacement of emulsion droplets over time and changes in the viscoelastic properties. Here, novel and promising cellulose-based oil-in-water (O/W) emulsions were prepared and studied, for the first time, by DWS. Cellulose plays the role of a novel eco-friendly emulsifying agent. The hydrolysis time of cellulose was observed to affect the average size of the emulsion droplets and their stability; the longer the hydrolysis time, the more dispersed and stable the emulsions were found to be. Additionally, a good complementarity between the microrheology (DWS) and macrorheology (mechanical rheometer) data was found. Our work suggests that DWS is a highly attractive method to investigate the stability, aging and microrheology properties of cellulose-based emulsions, providing valuable insights on their microstructure. This technique is thus highly appealing for the characterization and design of novel emulsion formulations.

Keywords
Diffusing wave spectroscopy, Cellulose, Emulsions, Microrheology
National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-34407 (URN)10.1016/j.jcis.2018.07.043 (DOI)000444067300025 ()30032009 (PubMedID)2-s2.0-85050164802 (Scopus ID)
Available from: 2018-09-13 Created: 2018-09-13 Last updated: 2018-09-28
Lindman, B., Medronho, B., Alves, L., Costa, C., Edlund, H. & Norgren, M. (2017). The relevance of structural features of cellulose and its interactions to dissolution, regeneration, gelation and plasticization phenomena. Physical Chemistry, Chemical Physics - PCCP, 19(35), 23704-23718
Open this publication in new window or tab >>The relevance of structural features of cellulose and its interactions to dissolution, regeneration, gelation and plasticization phenomena
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2017 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 19, no 35, p. 23704-23718Article in journal (Refereed) Published
Abstract [en]

Cellulose is the most abundant polymer and a very important renewable resource. Since cellulose cannot be shaped by melting, a major route for its use for novel materials, new chemical compounds and renewable energy must go via the solution state. Investigations during several decades have led to the identification of several solvents of notably different character. The mechanisms of dissolution in terms of intermolecular interactions have been discussed from early work but, even on fundamental aspects, conflicting and opposite views appear. In view of this, strategies for developing new solvent systems for various applications have remained obscure. There is for example a strong need for using forest products for higher value materials and for environmental and cost reasons to use water-based solvents. Several new water-based solvents have been developed recently but there is no consensus regarding the underlying mechanisms. Here we wish to address the most important mechanisms described in the literature and confront them with experimental observations. A broadened view is helpful for improving the current picture and thus cellulose derivatives and phenomena such as fiber dissolution, swelling, regeneration, plasticization and dispersion are considered. In addition to the matter of hydrogen bonding versus hydrophobic interactions, the role of ionization as well as some applications of new knowledge gained are highlighted.

National Category
Physical Chemistry
Identifiers
urn:nbn:se:miun:diva-31407 (URN)10.1039/C7CP02409F (DOI)000410585900012 ()28621781 (PubMedID)2-s2.0-85029414642 (Scopus ID)
Projects
Cello
Funder
Swedish Research Council, 2015-04290VINNOVA, 2013-05617
Available from: 2017-08-16 Created: 2017-08-16 Last updated: 2017-12-18Bibliographically approved
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