University of Oulu

Langmuir, 2018, 34, 8, 2800-2806. Publication Date: February 6, 2018.

Carboxymethyl chitosan and its hydrophobically modified derivative as pH-switchable emulsifiers

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Author: Kalliola, Simo1; Repo, Eveliina1; Srivastava, Varsha1;
Organizations: 1Lappeenranta University of Technology, Sammonkatu 12, Mikkeli FI-50130, Finland
2Research Unit of Sustainable Chemistry, University of Oulu, P.O. Box 3000, Oulu FI-90014, Finland
3Fibre and Particle Engineering Research Unit, University of Oulu, P.O. Box 4300, Oulu FI-90014, Finland
4Department of Civil and Environmental Engineering, Florida International University, Miami, Florida 33174, United States
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 6.2 MB)
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Language: English
Published: American Chemical Society, 2018
Publish Date: 2019-07-10


The emulsification properties of carboxymethyl chitosan (CMChi) and hydrophobically modified carboxymethyl chitosan (h-CMChi) were studied as a function of pH and dodecane/water ratio. The pH was varied between 6—10, and the oil/water ratio between 0.1—2.0. In CMChi solution, the emulsion stability increased as the pH was lowered from 10 to 7, and the phase inversion was shifted from oil/water ratio 1.0 to 1.8, respectively. The system behaved differently in pH 6 due to the aggregation of CMChi and the formation of nanoparticles (∼200—300 nm). No phase inversion was observed and the maximum amount of emulsified oil was reached at oil/water ratio 1.2. The h-CMChi showed similar behavior as a function of pH but, due to hydrophobic modification, the phase inversion was shifted to higher values in pH 7—10. In pH 6, the behavior was similar, but the maximum amount of emulsified oil was higher compared to CMChi. The amount of adsorbed particles correlated with the emulsified amount of oil. Reversible emulsification of dodecane was demonstrated by pH adjustment using CMChi and h-CMChi solutions. The formed emulsions were gel-like, suggesting particle–particle interaction.

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Series: Langmuir
ISSN: 0743-7463
ISSN-E: 1520-5827
ISSN-L: 0743-7463
Volume: 34
Issue: 8
Pages: 2800 - 2806
DOI: 10.1021/acs.langmuir.7b03959
Type of Publication: A1 Journal article – refereed
Field of Science: 116 Chemical sciences
215 Chemical engineering
Funding: This study was funded by the Academy of Finland (decision number 283200).
Copyright information: © 2018 American Chemical Society. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.