Cellulose Nanofiber/Nanocrystal Reinforced Capsules: A Fast and Facile Approach Toward Assembly of Liquid-Core Capsules with High Mechanical Stability
2014 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 15, no 5, 1852-1859 p.Article in journal (Refereed) Published
Liquid-core capsules of high mechanical stability open up for many solid state-like applications where functionality depending on liquid mobility is vital. Herein, a novel concept for fast and facile improvement of the mechanical properties of walls of liquid-core capsules is reported. By imitating nature's own way of enhancing the mechanical properties in liquid-core capsules, the parenchyma plant cells found in fruits and vegetables, a blend of short cellulose nanofibers (<1 mu m, NFC) and nanocrystals (CNC) was exploited in the creation of the capsule walls. The NFC/CNC blend was prepared from a new version of the classical wood pulp hydrolysis. The capsule shell consisted of a covalently (by aromatic diisocyanate) cross-linked NFC/CNC structure at the outer capsule wall and an inner layer dominated by aromatic polyurea. The mechanical properties revealed an effective capsule elastic modulus of 4.8 GPa at 17 wt % NFC/CNC loading, about six times higher compared to a neat aromatic polyurea capsule (0.79 GPa) and 3 orders of magnitude higher than previously reported capsules from regenerated cellulose (0.0074 GPa). The outstanding mechanical properties are ascribed to the dense nanofiber structure, present in the outer part of the capsule wall, that is formed by oriented NFC/CNC of high average aspect ratio (L/d similar to 70) and held together by both covalent (urethane bonds) and physical bonds (hydrogen bonds).
Place, publisher, year, edition, pages
2014. Vol. 15, no 5, 1852-1859 p.
Atomic-Force Microscope, Plant-Cell Wall, Pickering Emulsions, Native Cellulose, Nanocrystals, Microcapsules, Nanocomposites, Polyurethane, Nanocapsules, Films
Biochemistry and Molecular Biology Polymer Chemistry
IdentifiersURN: urn:nbn:se:kth:diva-146555DOI: 10.1021/bm500232hISI: 000335939800032ScopusID: 2-s2.0-84900406869OAI: oai:DiVA.org:kth-146555DiVA: diva2:724248
QC 201406122014-06-122014-06-122014-06-12Bibliographically approved