Stereoselectively water resistant hybrid nanopapers prepared by cellulose nanofibers and water-based polyurethane

TY - JOUR

T1 - Stereoselectively water resistant hybrid nanopapers prepared by cellulose nanofibers and water-based polyurethane

AU - Sethi, Jatin

AU - Farooq, Muhammad

AU - Österberg, Monika

AU - Illikainen, Mirja

AU - Sirviö, Juho Antti

PY - 2018/11/1

Y1 - 2018/11/1

N2 - Cellulose nanopapers, known for excellent mechanical properties, loses 90% of their stiffness in the wet conditions. In this study, we attempt to improve the wet mechanical properties of cellulose nanopaper by incorporating polyurethane by a novel and ecofriendly method. Water based PU was dispersed along with CNFs in water and hybrid nanopapers were prepared by draining water under vacuum followed by forced drying. These hybrid nanopapers have a gradient interpenetrating structure with PU concentrated towards one side and CNFs towards the other, which was confirmed by scanning electron microscopy, x-ray photoelectron spectroscopy and contact angle measurements. Because of this, the nanopapers are water resistant on one surface (PU rich side) and hydrophilic on the other (cellulose rich side), making them stereoselectively water resistant. When wetted with water on the PU side, the hybrid nanopaper with 10% PU is able to retain 65% modulus; on the other hand, the reference retains only 10% of the modulus. Similar results are seen in the tensile and the yield strength. Additionally, the hybrid nanopapers have higher elongation and improved thermal stability. The reported material is relevant to the applications such as flexible electronics and transparent displays.

AB - Cellulose nanopapers, known for excellent mechanical properties, loses 90% of their stiffness in the wet conditions. In this study, we attempt to improve the wet mechanical properties of cellulose nanopaper by incorporating polyurethane by a novel and ecofriendly method. Water based PU was dispersed along with CNFs in water and hybrid nanopapers were prepared by draining water under vacuum followed by forced drying. These hybrid nanopapers have a gradient interpenetrating structure with PU concentrated towards one side and CNFs towards the other, which was confirmed by scanning electron microscopy, x-ray photoelectron spectroscopy and contact angle measurements. Because of this, the nanopapers are water resistant on one surface (PU rich side) and hydrophilic on the other (cellulose rich side), making them stereoselectively water resistant. When wetted with water on the PU side, the hybrid nanopaper with 10% PU is able to retain 65% modulus; on the other hand, the reference retains only 10% of the modulus. Similar results are seen in the tensile and the yield strength. Additionally, the hybrid nanopapers have higher elongation and improved thermal stability. The reported material is relevant to the applications such as flexible electronics and transparent displays.

KW - Cellulose nanopapers

KW - Flexible composites

KW - Gradient interpenetrating network

KW - Hybrid materials

KW - Polyurethane

KW - Water resistance

UR - http://www.scopus.com/inward/record.url?scp=85049870535&partnerID=8YFLogxK

U2 - 10.1016/j.carbpol.2018.07.028

DO - 10.1016/j.carbpol.2018.07.028

M3 - Article

VL - 199

SP - 286

EP - 293

JO - Carbohydrate Polymers

JF - Carbohydrate Polymers

SN - 0144-8617

ER -