Cellulose Nanofiber/Nanocrystal Reinforced Capsules: A Fast and Facile Approach Toward Assembly of Liquid-Core Capsules with High Mechanical Stability

Abstract

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 μm, 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 ∼ 70) and held together by both covalent (urethane bonds) and physical bonds (hydrogen bonds).

Strategies for structuring diverse emulsion systems by using wood lignocellulose-derived stabilizers

“…138 Svagan et al crosslinked hexadecane o/w emulsions stabilized by a mixture of CNC and CNF using aromatic polyurea to produce a protective mechanical barrier for liquid-core microcapsules. 139…”

Highly Thermal‐Resilient AgNW Transparent Electrode and Optical Device on Thermomechanically Superstable Cellulose Nanorod‐Reinforced Nanocomposites

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PMMA@SCNC composite microspheres prepared from pickering emulsion template as curcumin delivery carriers

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