Environmental friendly and sustainable gas barrier on porous materials: Nanocellulose coatings prepared using spin- and dip-coating

• Oxygen barrier coatings solely based on nanosize cellulose were developed.
• The coating thickness varied from hundreds of nanometers for spin-coated layers, to micrometers for dip-coated ones.
• Nanosize cellulose coatings showed better oxygen barrier than polymers such as PE and PS in dry conditions.
• Thin nanocellulose coatings were sensitive for humidity and long term storage.

In this study, environmental friendly and sustainable coatings of nanocellulose (NC) were prepared using spin- and dip-coating methods, on two different porous cellulose substrates. Microscopy studies showed that spin-coating technique was suitable for the substrate with smaller pore size, while the dip-coating was suitable for the substrate with larger pore size. The coating thickness ranged from some hundreds of nanometers for the spin-coated layers, to some micrometers for the dip-coated ones. It was also seen that the contact angle increased with the coating thickness and roughness. NC coating resulted in low oxygen permeability (between 0.12 and 24 mL ∗ μm/(m2 ∗ 24 h ∗ kPa)) at 23% RH, but at 50% RH the oxygen permeability was too high to be measured, except for the dip-coated sample with 23 μm thickness. Also, it was seen that eight month storing reduced the barrier properties of the coatings when compared with fresh materials. These results indicate that NC coatings have a great potential as sustainable alternative coating on paperboard.

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