Effects of hydrophobic polyhedral oligomeric silsesquioxane coating on water vapour barrier and water resistance properties of paperboard

The substitution of fossil based packaging materials with materials from renewable sources is a topic of current interest. Polyhedral oligomeric silsesquioxanes with fatty acid moieties can have a renewable content of more than 90 % and are therefore called bio-POSS. In this study the bio-POSS octa-(ethyl erucamide) silsesquioxane was coated on a paperboard substrate as a liquid coating. The water resistance and the water vapour barrier properties of the paperboard were improved. Samples on which the bio-POSS coating layer was dried at 80 °C had a slightly higher water resistance and water vapour barrier than samples dried at room temperature. UV treatment of the coating layer had little effect. Solid state ¹H-NMR of UV treated coatings showed no reaction of double bonds of bio-POSS in the coating layer. Multiple coating considerably enhanced the water resistance and water vapour barrier properties of the paperboard, due to an increase in the coating thickness and a reduction in number of pores on top coated surfaces.