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Nanopaper membranes from chitin-protein composite nanofibers: Structure and mechanical properties
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.ORCID iD: 0000-0002-4100-6076
KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.ORCID iD: 0000-0001-9832-027X
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.ORCID iD: 0000-0001-5818-2378
2014 (English)In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 131, no 7, 40121- p.Article in journal (Refereed) Published
Abstract [en]

Chitin nanofibers may be of interest as a component for nanocomposites. Composite nanofibers are therefore isolated from crab shells in order to characterize structure and analyze property potential. The mechanical properties of the porous nanopaper structures are much superior to regenerated chitin membranes. The nanofiber filtration-processing route is much more environmentally friendly than for regenerated chitin. Minerals and extractives are removed using HCl and ethanol, respectively, followed by mild NaOH treatment and mechanical homogenization to maintain chitin-protein structure in the nanofibers produced. Atomic force microscope (AFM) and scanning transmission electron microscope (STEM) reveal the structure of chitin-protein composite nanofibers. The presence of protein is confirmed by colorimetric method. Porous nanopaper membranes are prepared by simple filtration in such a way that different nanofiber volume fractions are obtained: 43%, 52%, 68%, and 78%. Moisture sorption isotherms, structural properties, and mechanical properties of membranes are measured and analyzed. The current material is environmentally friendly, the techniques employed for both individualization and membrane preparation are simple and green, and the results are of interest for development of nanomaterials and biocomposites.

Place, publisher, year, edition, pages
2014. Vol. 131, no 7, 40121- p.
Keyword [en]
biomaterials, fibers, mechanical properties, membranes, porous materials
National Category
Polymer Technologies
URN: urn:nbn:se:kth:diva-142316DOI: 10.1002/app.40121ISI: 000331004100054ScopusID: 2-s2.0-84892586454OAI: diva2:703009

QC 20140305

Available from: 2014-03-05 Created: 2014-02-28 Last updated: 2014-11-10Bibliographically approved
In thesis
1. Chitin nanofibers, networks and composites: Preparation, structure and mechanical properties
Open this publication in new window or tab >>Chitin nanofibers, networks and composites: Preparation, structure and mechanical properties
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Chitin is an important reinforcing component in load-bearing structures in many organisms such as insects and crustaceans (i.e. shrimps, lobsters, crabs etc.). It is of increasing interest for use in packaging materials as well as in biomedical applications. Furthermore, biological materials may inspire the development of new man-made material concepts. Chitinmolecules are crystallized in extended chain conformations to form nanoscale fibrils of about 3 nm in diameter. In the present study, novel materialshave been developed based on a new type of chitin nanofibers prepared from the lobster exoskeleton. Improved understanding about effects of chitin from crustaceans and chitin material preparation on structure is provided through Atomic Force Microscopy(AFM) (paper I&II), Scanning Transmission Electron Microscopy(STEM) (paper I&II), X-Ray Diffraction (XRD), Intrinsic Viscosity, solid state 13C Nuclear Magnetic Resonance (NMR) (paper II), Field Emission Scanning Electron Microscopy(FE-SEM) (paper I, II, III, IV & V), Ultraviolet-Visible Spectrophotometryand Dynamic Light Scattering (DLS) (paper III). The presence of protein was confirmed through colorimetric method(paper I & II). An interesting result from the thesis is the new features of chitin nanofiber including small diameter, high molar mass or nanofiber length,and high purity. The structure and composition of the nanofibers confirms this (paper I & II). Furthermore, the structure and properties of the corresponding materials confirm the uniqueness of the present nanofibers: chitin membrane (I & II), polymer matrix composites (III),and hydrogels (paper IV).

Improved mechanical properties compared with typical data from the literature were confirmed for chitin nanofiber membranes in paper II, chitin-chitosan polymer matrix composites in paper III, and chitin hydrogel in paper IV. Mechanical tests included dynamic mechanical analysis and uniaxial tensile tests. Mechanical properties of chitin hydrogels were evaluated based onrheological and compression properties (paper IV). The values were the highest reported for this kind of chitin material. Furthermore, the relationships between materials structure and properties were analyzed. For membranes and polymer matrix nanocomposites, the degree of dispersion is an important parameter. For the hydrogels, the preparation procedure is very simple and has interesting practical potential.

Chitin-binding characteristics of cuticular proteins areinteresting fornovel bio-inspired material development. In the present work(paper V), chitin nanofibers with newfeaturesincluding high surface area and low protein content were combined with resilin-like protein possessing the chitin-binding characteristics. Hydrated chitin-resilin nanocomposites with similar composition as in rubber-like insect cuticles were prepared. The main objective was to improve understanding on the role of chitin-binding domain on mechanical properties. Resilin is a rubber-like protein present in insects. The exon I (comprising 18 N-terminal elastic repeat units) together with or without the exon II (a typical cuticular chitin-binding domain) from the resilin gene CG15920 found in Drosophila melanogasterwere cloned and the encoded proteins were expressed as soluble products in Escherichia coli.Resilin-like protein with chitin-binding domain (designated as ResChBD) adsorbedin significant amount to chitin nanofiber surface andprotein-bound cuticle-like soft nanocomposites were formed. Although chitin bindingwas taking place only in proteinswith chitin-binding domain, the global mechanical behavior of the hydrated chitin-resilin nanocomposites was not so sensitive to this chitin-resilin interaction.

In summary, chitin is an interesting material component with high potential as mechanical reinforcement in a variety of nanomaterials. The present study reports the genesisof novel chitin nanofibers and outlines the basic relationships between structure and properties for materials based on chitin. Future work should be directed towards both bio-inspired studies of the nanocomposite chitin structures in organisms, as well as the industrial applications of chitin waste from the food industry. Chitin nanofibers can strengthen the properties of materials, andprovide optical transparency as well as biological activities such as antimicrobial properties.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. ix, 66 p.
TRITA-CHE-Report, ISSN 1654-1081 ; 2014:43
Chitin, chitin materials, membranes, hydrogels, nanocomposites, mechanical properties, bioinspiration, lobster
National Category
Polymer Technologies
Research subject
Fibre and Polymer Science
urn:nbn:se:kth:diva-155528 (URN)978-91-7595-312-0 (ISBN)
Public defence
2014-11-28, Kollegiesalen, Brinellvägen 8, KTH, Stockholm, 13:00 (English)
Formas, 63619

QC 20141110

Available from: 2014-11-10 Created: 2014-11-06 Last updated: 2014-11-10Bibliographically approved

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