Master Thesis: Silver labeling of cellulose nanofibrils (CNFs)
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Nanocellulose is already being used in products and its market footprint is only expected to grow. Product safety concerns regarding nanocellulose usage in consumer goods require nanocellulose grades that are labeled with a detectable marker to facilitate localization, particularly in terms of leaching from products. Thus, new nanocellulose labeling approaches need to be explored, with the following criteria: (1) easy and reproducible chemistry, (2) labeling does not significantly alter the properties of the nanocellulose, and (3) the degree labeling is sufficient to allow facile detection. One such promising avenue for the labeling and identification of nanocellulose is by the attachment of silver nanoparticles (NPs).
In this thesis project, cellulose nanofibrils (CNFs) will be labeled with silver NPs. The starting pulp will be decorated with silver nanoparticles using a straightforward and non-toxic approach that has previously been applied to paper substrates.1 Briefly, the approach involves combining the cellulose substrate, silver salts, and glucose as a reducing agent, and heating (microwave or oven) to grow silver NPs on the surface of the fibers. The pulps will then be defibrillated to different extents in a microfluidizer (i.e. varying pass number). The degree of silver decoration will be characterized by UV-Vis reflectance spectroscopy, elemental analysis, and transmission electron microscopy. Uncharged and carboxymethylated pulps will be explored; it is expected that the charged pulps will be decorated more since the negative carboxymethyl groups can act as anchors for cationic silver ions. Alternatively, and if necessary, Ag NPs can be grown directly onto ready-made CNFs of varying charge and degree of fibrillation.
Other complimentary routine tools including dry content measurement, dynamic light scattering, and zeta-potential may be utilized to characterize the Ag NP-decorated materials before and after decoration.
Final application date: 15/1, 2019.
If you have any questions about the master thesis project, please contact Recruiting Manager Tiffany Abitbol, tel. 070 377 6036. Union representatives: Anna Jensen (Unionen), 08-676 72 23 and Elisabeth Sjöholm (Sveriges Ingenjörer), 08-676 74 44.
Master thesis, RISE, Bioeconomy, cellulose nanofibrils (CNFs), Stockholm, exjobb, uppsats
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