Nanotechnology in the service of wood preservation

In recent years, wood preservation research has focused on developing environmentally friendly wood protection agents, including nanoparticles. Previous studies have shown that, depending on their size, nanoparticles can effectively penetrate wood and can also enter into a reciprocal relationship with the wood components. The findings of different studies are difficult to compare, however, because particle size is only one of many factors affecting wood impregnation. In this project, researchers systematically investigated the potential of nanotechnology for wood preservation.

The durability of wood can be improved by wood protection agents, which hamper decomposition by microorganisms and insects or, ideally, prevent it entirely. The chemical substances in the wood preservation agents are released gradually over time, which poses a sizable risk to the environment and also reduces their effectiveness. Consequently, one of the aims of the research was to develop wood preservation agents that are both highly effective and as environmentally friendly as possible. Nanoparticles have an important role to play in this context owing to their specific surface characteristics and functionality. Wood protection agents already in use include "micronised copper", which contains a wide range of particle sizes and a substantial amount of nanoparticles. However, there is still a great need for research on the impregnation and distribution of the nanoparticles as well as on their optimisation and process parameters.

The researchers wished to investigate the properties of newly developed nanoparticles for wood preservation. They were particularly interested in the protective effect of the particles on wood and the mechanisms behind it. They also paid particular attention to whether the use of nanomaterials is associated with risks to the environment or to human health.
To achieve these goals, experts from various disciplines worked closely together in this project. They contributed know-how from particle synthesis and characterisation, wood technology, microscopy and nanotoxicology.

The results of this project could lead to the development of marketable nanotechnology-based wood treatments. The findings of the project will help to improve existing methods of wood preservation and to advance the development of new applications of nanotechnology in the economically important building and construction sector.

As a result of the research project, the scientists have a deeper understanding of the behaviour and distribution of nanoparticles in wood. The scientists now know how the nanoparticles interact with molecules in wood, and can estimate the nanoparticles’ protective effect. To arrive at these findings, the scientists had to develop methods that enabled them to see how very small amounts of particles are stored.
These methods help the scientists to better understand wood impregnation by wood preservation agents based on metal nanoparticles, such as copper. In addition, thanks to the findings of the project, the scientists can now much more easily and accurately determine how many nanoparticles are actually deposited in the wood. The size and surface properties of the nanoparticles used in wood preservation can also now be more accurately determined and thus optimised. This facilitates the basic study and commercial exploitation of wood preservation agents containing nanoparticles.

Through their investigations, the research team was able to determine the minimum concentration of nanoparticles required to effectively protect various types of foliage and conifers. Knowing this threshold is essential for the economical and environmentally sensible use of nanoparticles.

A further finding of this research project was the development of a simple and cost-effective method of characterising the size distribution and shape of nanoparticles. Researchers now have an easily accessible tool for analysing wood preservation agents containing nanoparticles.

The project also collected data on the nature of the link between the surface of the nanoparticles and the cell walls in the wood. For this purpose, the researchers developed a novel method of measurement that could potentially replace the current useful but very time-consuming approaches.

Implications for the wood (preservation) industry