Periodic Reporting for period 4 - WoodNanoTech (Wood Nanotechnology for Multifunctional Structures)
Período documentado: 2022-03-01 hasta 2022-08-31
Nanocellulose research is an enormously large activity, with hundreds if not thousands of active research groups all over the world. In addition, there is a growing body of industrial products based on nanocellulose. It has proved difficult to manufacture large structures with controlled nanoscale dispersion and orientation of cellulose nanofibrils. The present project offers a different strategy. The intrinsic structure of wood, with its oriented and dispersed cellulose nanofibrils, is preserved but tailored for various applications. In this way, it becomes possible to manufacture meter-long structures with controlled hierarchical organization at both micro, meso and nanoscale.
This idea offers a novel route towards advanced wood products, where the eco-friendly characteristics of wood are combined with modern nanotechnology. This makes it possible to extend the application areas for wood structures, and also provide inspiration for novel modification methods. Trees offer many advantages. There is no competition with food products, forestry in northern Europe is sustainable in that a new tree is planted for every tree harvested, and the product life of many wood products is long.
The goals are to develop a wood nanotechnology toolbox for materials design of transparent wood used in engineering structures, where optical device functions are integrated. The hierarchical structure of the material is tailored, and the science for scalable processing concepts is developed. Potential applications include solar cells, electrochromic windows and lighting systems which could be based on molecular dyes or quantum dots dispersed in transparent wood. One vision is load-bearing transparent panels, including light systems, or tailored for specific optical effects. An important goal developed during the project, was to analyze the material in the context of th life cycle of transparent wood. This is illustrated in the enclosed figure from Montanari, C.; Olsen, P.; Berglund, L. A. Frontiers in Chemistry 2021, 9.DOI: 10.3389/fchem.2021.682883.
This idea offers a novel route towards advanced wood products, where the eco-friendly characteristics of wood are combined with modern nanotechnology. This makes it possible to extend the application areas for wood structures, and also provide inspiration for novel modification methods. Trees offer many advantages. There is no competition with food products, forestry in northern Europe is sustainable in that a new tree is planted for every tree harvested, and the product life of many wood products is long.
The goals are to develop a wood nanotechnology toolbox for materials design of transparent wood used in engineering structures, where optical device functions are integrated. The hierarchical structure of the material is tailored, and the science for scalable processing concepts is developed. Potential applications include solar cells, electrochromic windows and lighting systems which could be based on molecular dyes or quantum dots dispersed in transparent wood. One vision is load-bearing transparent panels, including light systems, or tailored for specific optical effects. An important goal developed during the project, was to analyze the material in the context of th life cycle of transparent wood. This is illustrated in the enclosed figure from Montanari, C.; Olsen, P.; Berglund, L. A. Frontiers in Chemistry 2021, 9.DOI: 10.3389/fchem.2021.682883.
The project activities have been in three integrated areas: a) the science of transparent wood processing, b) structure-property relationships in transparent wood biocomposites and c) nanotechnologies for new devices based on transparent wood. The project team is cross-disciplinary with competence in wood science, polymer synthesis, nanostructured biocomposites and photonics. The contribution from physicists with optics and photonics expertise has been particularly important for team progress. This is not only through high productivity in terms of contributions to scientific publications, but also in development of experimental protocols, new ideas (wood for light wave-guiding and laser function) and focus on fundamental understanding of mechanisms for light scattering and absorption.
In processing science, the main concept is chemical pretreatment of wood veneer, followed by impregnation of polymer precursors and polymerisation. Several new methods have been developed and biobased polymer systems were developed. The optical transmittance of transparent wood has been investigated in great detail. This is critical in order to tailor these materials, and to come up with new material concepts. We keep increasing the understanding of how light travels through a complex material which is neither random nor highly organized in structure, but something inbetween. So far, we have not seen fundamental work in this direction in the literature. We published a combined theoretical and experimental approach to model light propagation mechanisms in scattering biocomposites. H Chen C Montanari R Shanker S Marcinkevicius LA Berglund, I Sychugov, Advanced Optical Materials 2022. DOI: 10.1002/adom.202102732.
The mechanical performance of transparent wood based on birch is exceptionally good. An important reason is in the new processing approach combined with removal of some wood components which do not contribute much to mechanical properties in polymer matrix biocomposites. Finally, many new devices have been investigated, including luminescent wood, a wood laser, electrochromic windows, transparent wood for heat storage using phase change materials, and solar cells. Plywood structures have been developed in order to control anisotropy of transparent wood laminates. In summary, the project is progressing well, and the team is functioning well with seamless integration between wood nanotechnology and photonics activities.
We have published 37 contributions in scientific journals, already with more than 1500 citations and many contributions are therefore obviously well-cited and in high-impact journals. This is particularly true if one considers the typical impact factors for publications in the area of forest products. In addition, 5 PhD-theses have resulted from the project. 2 of those PhD's are working in industry, 1 in a research institute and 2 are postdocs.
In processing science, the main concept is chemical pretreatment of wood veneer, followed by impregnation of polymer precursors and polymerisation. Several new methods have been developed and biobased polymer systems were developed. The optical transmittance of transparent wood has been investigated in great detail. This is critical in order to tailor these materials, and to come up with new material concepts. We keep increasing the understanding of how light travels through a complex material which is neither random nor highly organized in structure, but something inbetween. So far, we have not seen fundamental work in this direction in the literature. We published a combined theoretical and experimental approach to model light propagation mechanisms in scattering biocomposites. H Chen C Montanari R Shanker S Marcinkevicius LA Berglund, I Sychugov, Advanced Optical Materials 2022. DOI: 10.1002/adom.202102732.
The mechanical performance of transparent wood based on birch is exceptionally good. An important reason is in the new processing approach combined with removal of some wood components which do not contribute much to mechanical properties in polymer matrix biocomposites. Finally, many new devices have been investigated, including luminescent wood, a wood laser, electrochromic windows, transparent wood for heat storage using phase change materials, and solar cells. Plywood structures have been developed in order to control anisotropy of transparent wood laminates. In summary, the project is progressing well, and the team is functioning well with seamless integration between wood nanotechnology and photonics activities.
We have published 37 contributions in scientific journals, already with more than 1500 citations and many contributions are therefore obviously well-cited and in high-impact journals. This is particularly true if one considers the typical impact factors for publications in the area of forest products. In addition, 5 PhD-theses have resulted from the project. 2 of those PhD's are working in industry, 1 in a research institute and 2 are postdocs.
1. Nanostructured wood templates
Delignified wood veneer is a very interesting and new wood material with excellent potential in new forest products. We are developing expertise in this area for new knowledge and exploitation in new products. A new method for wood treatment has been developed, based on new understanding of how lignin and its removal is influencing wood scaffold nanostructure.
2. Processing for nanostructural control
We have been able to process transparent wood with silicon quantum dots of controlled distribution so that the material became luminescent, and a candidate for load-bearing LED panels for indoor lighting. Thick transparent wood (TW) has been achieved, towards 1 cm, through chemical pretreatment. By controlling the distribution of phase change materials in TW, thermal energy storage function has been integrated in TW. The media interest in this work has been enormous.
3. Mechanical behaviour
The concept of TW plywood has been developed, in order to control anisotropy of mechanical properties. Exceptional mechanical properties have been reported for transparent birch. The current processing concept makes it possible to reach properties not previously attainable in wood biocomposites.
4. Wood photonics
Electrochromic window devices have been investigated, where transmittance can be controlled by electrical current. TW solar cells have also been prepared. Wood lasing has been achieved, and this is of great technical and scientific interest. A patent application has been submitted. Optical coherence in TW has been analyzed as well as light scattering mechanisms and light polarization and anisotropy effects. A model has been developed for thickness dependence of transmittance in scattering composites.
We managed to increase the specific surface area of delignified wood scaffolds, for the purpose of more efficient functionalisation. As an example, the optical performance of luminescent composites and wood lasers were improved. Another achievement is structural color in wood, which is a new approach compared with the use of organic dyes or coatings. A scientific task is to control the dispersion and distribution of dyes and nanoparticles in TW, in order to create new functions. Modeling results for optical properties were published, and will support future experimental activities. A more complete understanding of photon transport in transparent wood composites was developed.
Delignified wood veneer is a very interesting and new wood material with excellent potential in new forest products. We are developing expertise in this area for new knowledge and exploitation in new products. A new method for wood treatment has been developed, based on new understanding of how lignin and its removal is influencing wood scaffold nanostructure.
2. Processing for nanostructural control
We have been able to process transparent wood with silicon quantum dots of controlled distribution so that the material became luminescent, and a candidate for load-bearing LED panels for indoor lighting. Thick transparent wood (TW) has been achieved, towards 1 cm, through chemical pretreatment. By controlling the distribution of phase change materials in TW, thermal energy storage function has been integrated in TW. The media interest in this work has been enormous.
3. Mechanical behaviour
The concept of TW plywood has been developed, in order to control anisotropy of mechanical properties. Exceptional mechanical properties have been reported for transparent birch. The current processing concept makes it possible to reach properties not previously attainable in wood biocomposites.
4. Wood photonics
Electrochromic window devices have been investigated, where transmittance can be controlled by electrical current. TW solar cells have also been prepared. Wood lasing has been achieved, and this is of great technical and scientific interest. A patent application has been submitted. Optical coherence in TW has been analyzed as well as light scattering mechanisms and light polarization and anisotropy effects. A model has been developed for thickness dependence of transmittance in scattering composites.
We managed to increase the specific surface area of delignified wood scaffolds, for the purpose of more efficient functionalisation. As an example, the optical performance of luminescent composites and wood lasers were improved. Another achievement is structural color in wood, which is a new approach compared with the use of organic dyes or coatings. A scientific task is to control the dispersion and distribution of dyes and nanoparticles in TW, in order to create new functions. Modeling results for optical properties were published, and will support future experimental activities. A more complete understanding of photon transport in transparent wood composites was developed.