Cellulose nanofiber/nanocrystal reinforced capsules: a fast and facile approach toward assembly of liquid-core capsules with high mechanical stability

TY - JOUR

T1 - Cellulose nanofiber/nanocrystal reinforced capsules

T2 - a fast and facile approach toward assembly of liquid-core capsules with high mechanical stability

AU - Svagan, Anna J.

AU - Musyanovych, Anna

AU - Kappl, Michael

AU - Bernhard, Max

AU - Glasser, Gunner

AU - Wohnhaas, Christian

AU - Berglund, Lars A.

AU - Risbo, Jens

AU - Landfester, Katharina

PY - 2014/5/12

Y1 - 2014/5/12

N2 - 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 natures 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).

AB - 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 natures 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).

U2 - 10.1021/bm500232h

DO - 10.1021/bm500232h

M3 - Journal article

C2 - 24716647

SN - 1525-7797

VL - 15

SP - 1852

EP - 1859

JO - Biomacromolecules

JF - Biomacromolecules

IS - 5

ER -