Forest

Chalmers researchers hunt for new resources in the forest

​Wallenberg Wood Science Center researches into possibilities to create new, hi-tech materials from trees, beyond the traditional cellulose fibres. The center involves 15 researchers at 5 departments and helps lay the foundations for successful research. And it is just starting to kick into a higher gear.
The researchers involved in the center is listed in the end of the article.
Transparent wood from nanocellulose, flame-resistant cellulose foams for isolation, and plastic-like packaging materials  made of hemicellulose – just some examples of new, wood-based material concepts developed in Sweden which have made headlines in recent years. Bio-based batteries and solar cells, and artificial ‘wood’ which can be 3D printed are others which have caught the collective imagination. But something maybe less well-known is the fact that most of these ideas are the result of one forward-thinking research programme, launched over ten years ago – Wallenberg Wood Science Center.

When the Knut and Alice Wallenberg Foundation announced a funding investment of close to half a billion kronor, Chalmers and KTH first set themselves as competitors. But on the initiative of the Foundation, they became collaborative partners instead. And several years before the programme was even complete, a programme for extension was sketched out, for scaling up and broadening. Within a year, WWSC 2.0 was launched, to last until 2028. Linköping University will now take part as well, and industrial partners are also involved in financing via the research platform, Treesearch. The Chalmers Foundation will also contribute with more research money. In total, over a billion kronor will be invested in forestry related material research in the coming decade, with an interdisciplinary approach combining biotechnology, material science and physical chemistry.
 

Delivering important competence

Lisbeth Olsson, Professor in Industrial Biotechnology, is Vice Director  of WWSC, and is responsible for Chalmers’ research within the programme. When she looks over what the research center has already delivered, it is not those headline-generating new materials that she sees as the principal contributions.
“I would probably say that the most important thing the WWSC has given the forestry industry is competence. Many doctoral students and postdocs from the programme have gone onto employment in the industry,” she says. 
 
This increased knowledge around foundational questions has clearly contributed to the fact that the forest industry today is a lot more future-oriented. When WWSC began in 2008, research was, according to Lisbeth Olsson, still very traditional, focused on the pulp and paper industry.
“Today, we instead define materials by what molecular properties they have. We discuss these things in a totally different way. So even if the industry in large part produces the same paper, packaging materials and hygiene products as ten years ago, there’s a molecular perspective on the future.”
 

All the parts of a tree can be better utilised

What drives these developments is the goal of a more sustainable society, and a phase-out of fossil fuels. With this environmental perspective there is also an increased demand on material and energy effectiveness. In the long term, this means that it is not sustainable – even with a renewable resource – to destroy or waste potentially valuable components of wood. Which, in many respects, is what the traditional pulp industry does today, when considering lignin.
“An essential idea within WWSC is to make better use of all the different parts of trees. The vision is to create some kind of bio-refinery for material,” says Lisbeth Olsson. 
 
Until now, research has been largely focused on new ways of using cellulose, for example in the form of nanocellulose, as well as investigating the potential of hemicellulose – such as recycling polymers to create dense layers or using it as a constituent part of composite materials. 
“As research continues, we will also devote a lot more energy to looking at lignin, which with its aromatic compounds has a totally different chemistry. One idea is to carbonise the molecules to give them electrical properties,” says Lisbeth Olsson.

When not busy with leading Chalmers’ activities within WWSC, which involves 5 different departments and around 15 researchers, she spends most of her time on her own research. Together with her colleagues, Lisbeth Olsson is investigating how enzymes and microorganisms can be used to separate and modify the constituent parts of trees – before reassembling them into materials with new, smart qualities.

First, a need for understanding at a deeper level

We leave the office and go downstairs to the industrial biotechnology laboratory for a quick tour among the petri dishes and fermentation vessels. Of around 40 employees, 5 work here full time, deriving materials from trees’ raw parts. 
 
​“We look a lot at how different fungi from the forest break down wood, which enzymes they use. We can also ‘tweak’ the enzymes, so that they, for example, make a surface modification instead of breaking a chemical bond ,” says Lisbeth Olsson, adding that they are even investigating examples such as heat resistant wood fungi from Vietnamese forests.
 
“When we find some interesting ability in a filamentous mushroom, for example, we can use genetic techniques to extract that ability to bacteria or yeast. That can then produce the same enzyme at a larger scale.”
 
A difficulty with a natural material like wood is its particularly heterogenous and complex makeup. To be able to understand what is happening at a deep level, researchers must study different cycles at different scales simultaneously – from micrometres down to fractions of a nanometre. Lisbeth Olsson and her colleagues are not yet down to that level of detail that is really needed. 
 
“We have a model of what we think trees look like. But we don’t really know for sure,” she explains.
 

Big investment opens up new possibilities

But soon, new possibilities will arise. The Wallenberg Foundation and Treesearch will together invest up to 200 billion kronor in building and operating a proprietary particle beam at the synchrotron facility Max IV outside Lund. The instrument, named Formax, could be compared to an extremely powerful x-ray microscope, and is specifically designed for tree-related material research. It will be ready for the first test experiments from 2021. 
 
But if the researchers have now identified a number of potent enzymes which could contribute to innovative biomaterials, how do they really dig down into wood’s structure at the smallest level? 

One possible answer is found a few more flights of stairs down in the Chemistry building, where the Division of Forest Products and Chemical Engineering is based. Here, research assistant Tuve Mattsson, with one of the division’s doctoral students, has just carried out a small steam explosion of a ring of wood chips. The method, in brief, involves soaked wood chips being trapped in a pressure vessel, before steam is pumped in. The temperature and pressure greatly increase, before the valve suddenly opens. Bang! Water in the wood starts to boil and expand and bursts the wood from the inside.

“To the naked eye, the chip pieces are quite similar – they just change colour. But look at them in a scanning electron microscope, and you see quite clearly how the structures have opened themselves up, just a little,” says Tuve Mattsson.
“We don’t want to break down the wood too much. Then you lose the effectivity both in terms of materials and energy” adds Lisbeth Olsson. “This could be a future processing stage to make it milder, more enzymatic methods possible in industry. Such methods are also a prerequisite to being able to realise another key vision of WWSC – that new materials should be able to be recirculated without losing their value.”
“This is a big challenge for the future. When a product has outlived its purpose, you should be able to extract the different material components and build them together in a new way, to create something of equal quality,” says Lisbeth Olsson.
“If we succeed with that, then that thought process must be present from the beginning.”

 

Chalmers researchers within WWSC

Biology and biological sciences: Johan Larsbrink, Lisbeth Olsson
Industrial and materials science: Roland Kádár
Microtechnology and nanoscience: Peter Enoksson

Mimicking wood’s ultrastructure with 3D printing

Porous, strong and rigid. Wood is a fantastic material. Now, researchers at the Wallenberg Wood Science Center have succeeded in utilising the genetic code of the wood to instruct a 3D bioprinter to print cellulose with a cellular structure and properties similar to those of natural wood, but in completely new forms.
 

Published: Mon 31 Aug 2020.