Cuticle-inspired barriers for lignocellulose materials

We have created moisture-barrier films using the second most abundant C16 hydroxy fatty acid (Fig. 1)1. These are semicrystalline materials with different degrees of toughness. The material shows a high “apparent” hydrophobicity, as revealed by contact angle measurements (110-130°, much higher than for PLA). The reason is due to the rough surface that we create during the formation of the films. Hence, instead of Nature’s two-layer system with a loose wax layer, we here create a one-layer structure with “built-in” surface roughness. In addition, the developed material has UV blocking properties. There are indications of that the oxygen barrier properties are also good, but further measurements are needed to verify that.  There are several ways to move forward here. The polymerization is made at elevated temperature for a relatively long period of time. There is room for improvement of the  polymerization route. In Nature the cutin polyester is a copolymer. Hence, the intention is to generate copolyesters with other C16 and/or C18 monomers, involving e.g. enzymatic routes. Ways of controlling the surface roughness and superhydrophobicity will also be in focus. We have also started to use our material as a water barrier on lignocellulosic substrates. There are potentially several materials developed within WWSC that our material can be coated on for improved water resistance and/or UV protection.

The project is part of Wallenberg Wood Science Center.