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Papers by Hjalmar Granberg
The use of the layer-by-layer technology and low density networks of cellulose nanofibrils for pr... more The use of the layer-by-layer technology and low density networks of cellulose nanofibrils for preparing new materials for energy storage
Novel method for producing formable low-density materials from self-assembled cellulose nanofibrils
Conventional electronics based on silicon, germanium, or compounds of gallium require prohibitive... more Conventional electronics based on silicon, germanium, or compounds of gallium require prohibitively expensive investments. A state-of-the-art microprocessor fabrication facility can cost up to $15 billion while using environmentally hazardous processes. In that context, the discovery of solution-processable conducting (and semiconducting) polymers stirred up expectations of ubiquitous electronics because it enables the mass-production of devices using well established high-volume printing techniques.In essence, this thesis attempts to study the characteristics and applications of thin conducting polymer films ( 100 μm). First, thin-films of organic materials were combined with an electric double layer capacitor to decrease the operating voltage of organic field effect transistors. In addition, ionic current-rectifying diodes membranes were integrated inside electrochromic displays to increase the device’s bistability and obviate the need for an expensive addressing backplane.This work also shows that it is possible to forgo the substrate and produce a self-standing electrochromic device by compositing the same water-processable material with nanofibrillated cellulose (plus a whitening pigment and high-boiling point solvents). In addition, we investigated the viability of these (semi)conducting polymer nanopaper composites in a variety of applications. This material exhibited an excellent combined electronic-ionic conductivity. Moreover, the conductivities in this easy-to-process composite remained constant within a wide range of thicknesses. Initially, this (semi)conducting nanopaper composite was used to produce electrochemical transistors with a giant transconductance (>1 S). Subsequently, it was used as electrodes to construct a supercapacitorwhose capacitance exceeds 1 F.
The energy consumption in the world is continuously growing and the sources of energy are largely... more The energy consumption in the world is continuously growing and the sources of energy are largely dominated by fossil fuels. However, the resources of oil, gas and coal are diminishing in capacity. Moreover the CO2 emissions arising from their combustion is a great concern because it induces climate changes that threaten our habitat. There is a dire need to look for alternative sources of energies and to minimize losses of energy in our surroundings. Heat engines and turbines typically running with fossil energy have efficiencies of about 35%, i.e. 65% of the energy is lost in the form of heat. Low temperature heat (<200 ᴼC) is almost always wasted in power plants, industries, automobiles and household appliances. This is a huge resource that can be directly converted to electricity through the concept of thermoelectricity. Major challenges for heat to electricity conversion include finding the abundant materials with efficient thermoelectric (TE) conversion that can be mass produced at low cost.This thesis presents an investigation of the TE properties of electronic and ionic conducting polymers, as well as their implementation in thermoelectric devices. This is a journey from thin solid films on a substrate to wet and liquid media and towards bulk structures utilizing the same core concept of thermoelectricity. The TE device concepts introduced here are suitable for various heat sources i.e. continuous, intermittent and instantaneous. The thesis has three major parts as follows:Conducting polymers (CPs) have been studied mainly as thin films. They have been synthesized in different ways and their properties have been compared to propose the most efficient amongst them for thermoelectricity. Simple methods of exposure to certain gases or liquids have been used to tune their TE properties and demonstrated its applications in thermoelectric generator (TEGs).Ionic materials have also been studied as potential candidates for thermoelectricity. Polyelectrolytes constitute a special class of electrolytes with dissimilar sizes of ions; a polymeric ion and a small counter ion. The movement of the small sodium (Na+) cation under heat gradient was explored in wet films and in solution. Because the ions could not cross the electrolyte-electrode junction, we propose the idea of ionic thermoelectric supercapacitor (ITESC), suitable for intermittent heat source.Nanofibrillated cellulose (NFC) has been used along with conducting polymers to realize the three dimensional conducting bulks as a TEG leg. NFC bulks were coated with conducting polymers as a first approach and later the mixture of (NFC & CP) was freeze-dried. The later approach resulted in mechanically flexible structures that were used as dual sensors for pressure and temperature based on the TE properties of the CP which can be utilized for electronic skin applications.The thesis shows new ways of utilizing waste heat using polymeric materials and points to a sensory application area, broadening the horizons of thermoelectricity.
The use of the layer-by-layer technology and low density networks of cellulose nanofibrils for pr... more The use of the layer-by-layer technology and low density networks of cellulose nanofibrils for preparing new materials for energy storage
The energy consumption in the world is continuously growing and the sources of energy are largely... more The energy consumption in the world is continuously growing and the sources of energy are largely dominated by fossil fuels. However, the resources of oil, gas and coal are diminishing in capacity. Moreover the CO2 emissions arising from their combustion is a great concern because it induces climate changes that threaten our habitat. There is a dire need to look for alternative sources of energies and to minimize losses of energy in our surroundings. Heat engines and turbines typically running with fossil energy have efficiencies of about 35%, i.e. 65% of the energy is lost in the form of heat. Low temperature heat (<200 ᴼC) is almost always wasted in power plants, industries, automobiles and household appliances. This is a huge resource that can be directly converted to electricity through the concept of thermoelectricity. Major challenges for heat to electricity conversion include finding the abundant materials with efficient thermoelectric (TE) conversion that can be mass prod...
A study has been made of the production of zinc oxide (ZnO) paper in a pilot paper machine. Bleac... more A study has been made of the production of zinc oxide (ZnO) paper in a pilot paper machine. Bleached sulphate softwood pulp (70%) and bleached sulphate hardwood pulp (30%) were corefined. Cationic ...
PaperCon 2019, held in Indianapolis, Indiana, USA, 5-8 May 2019, 2019
In moving towards a cellulose-based society, interdisciplinary effort is required as it is at thi... more In moving towards a cellulose-based society, interdisciplinary effort is required as it is at this interface that new ideas are found and can grow. New bio-based materials will play a key role but getting them into the marketplace is not always straightforward. Many options are available both for sourcing and for producing composite materials from wood-based cellulose and poly-lactic acid (PLA). Depending on how the material is processed, a multitude of properties can be generated. The main goal with this work was to attempt to reduce the research-to-market gap. This was done by testing a new way of working together where we bundled innovation-oriented projects and research-oriented projects around the theme of material experience. We then systematically worked with material demonstrators. In this article, we exemplify the results by focusing on one research-oriented project that did not at the outset have a market context and on one innovation-oriented project with clear market req...
Nordic Pulp and Paper Research Journal, 2012
Recent findings have shown that it is possible to use the Layer-by-Layer technique to create nano... more Recent findings have shown that it is possible to use the Layer-by-Layer technique to create nanofibrillated cellulose / polyethyleneimine interference films whose colour change with relative humidity. This study uses different optical models to describe spectral ellipsometry measurements data of interference films and how the film properties alter in dry and humid environments. The results indicate that water condensation initially is filling the surface pores within seconds whereas relaxation of the film to adjust to the added water is a slower process that reaches a steady state after »20 min. The maximum swelling ratio of the LbL films is almost independent of the number of layers within the film, but decreases considerably by crosslinking via heat treatment. The films show a distinct birefringence with optical axis perpendicular to the surface. Analysis of the moisture response with different optical models indicates that the films swell uniformly in the thickness direction wit...
Nordic Pulp and Paper Research Journal, 2004
Journal of Materials Chemistry A
Rolls of supercapacitor electrodes have successfully been produced on a pilot paper machine with ... more Rolls of supercapacitor electrodes have successfully been produced on a pilot paper machine with a novel material concept.
ACS Applied Polymer Materials
The global electrification of our society requires an enormous capacity of electrical energy stor... more The global electrification of our society requires an enormous capacity of electrical energy storage. This drives the demand for low-cost and sustainable solutions, where the electrode materials are key components. In the present work, all-organic supercapacitor electrodes have successfully been demonstrated to be produced on a pilot-scale paper machine, thereby showing the feasibility of large-scale production of “paper-based energy storage”. The material concept was based on activated charcoal from pyrolyzed coconut and cationized cellulose pulp, the latter having small amounts of electrostatically adsorbed PEDOT:PSS in order to create a conducting, percolating network. In a pre-trial lab experiment, it was evident that even small addition of 1 wt% PEDOT:PSS gave a large increase in capacitance compared to samples with only activated charcoal. In the pilot trials, the addition of carboxymethylated nanocellulose and/or carbon black was further investigated. The different additions ...
The use of the layer-by-layer technology and low density networks of cellulose nanofibrils for pr... more The use of the layer-by-layer technology and low density networks of cellulose nanofibrils for preparing new materials for energy storage
Novel method for producing formable low-density materials from self-assembled cellulose nanofibrils
Conventional electronics based on silicon, germanium, or compounds of gallium require prohibitive... more Conventional electronics based on silicon, germanium, or compounds of gallium require prohibitively expensive investments. A state-of-the-art microprocessor fabrication facility can cost up to $15 billion while using environmentally hazardous processes. In that context, the discovery of solution-processable conducting (and semiconducting) polymers stirred up expectations of ubiquitous electronics because it enables the mass-production of devices using well established high-volume printing techniques.In essence, this thesis attempts to study the characteristics and applications of thin conducting polymer films ( 100 μm). First, thin-films of organic materials were combined with an electric double layer capacitor to decrease the operating voltage of organic field effect transistors. In addition, ionic current-rectifying diodes membranes were integrated inside electrochromic displays to increase the device’s bistability and obviate the need for an expensive addressing backplane.This work also shows that it is possible to forgo the substrate and produce a self-standing electrochromic device by compositing the same water-processable material with nanofibrillated cellulose (plus a whitening pigment and high-boiling point solvents). In addition, we investigated the viability of these (semi)conducting polymer nanopaper composites in a variety of applications. This material exhibited an excellent combined electronic-ionic conductivity. Moreover, the conductivities in this easy-to-process composite remained constant within a wide range of thicknesses. Initially, this (semi)conducting nanopaper composite was used to produce electrochemical transistors with a giant transconductance (>1 S). Subsequently, it was used as electrodes to construct a supercapacitorwhose capacitance exceeds 1 F.
The energy consumption in the world is continuously growing and the sources of energy are largely... more The energy consumption in the world is continuously growing and the sources of energy are largely dominated by fossil fuels. However, the resources of oil, gas and coal are diminishing in capacity. Moreover the CO2 emissions arising from their combustion is a great concern because it induces climate changes that threaten our habitat. There is a dire need to look for alternative sources of energies and to minimize losses of energy in our surroundings. Heat engines and turbines typically running with fossil energy have efficiencies of about 35%, i.e. 65% of the energy is lost in the form of heat. Low temperature heat (<200 ᴼC) is almost always wasted in power plants, industries, automobiles and household appliances. This is a huge resource that can be directly converted to electricity through the concept of thermoelectricity. Major challenges for heat to electricity conversion include finding the abundant materials with efficient thermoelectric (TE) conversion that can be mass produced at low cost.This thesis presents an investigation of the TE properties of electronic and ionic conducting polymers, as well as their implementation in thermoelectric devices. This is a journey from thin solid films on a substrate to wet and liquid media and towards bulk structures utilizing the same core concept of thermoelectricity. The TE device concepts introduced here are suitable for various heat sources i.e. continuous, intermittent and instantaneous. The thesis has three major parts as follows:Conducting polymers (CPs) have been studied mainly as thin films. They have been synthesized in different ways and their properties have been compared to propose the most efficient amongst them for thermoelectricity. Simple methods of exposure to certain gases or liquids have been used to tune their TE properties and demonstrated its applications in thermoelectric generator (TEGs).Ionic materials have also been studied as potential candidates for thermoelectricity. Polyelectrolytes constitute a special class of electrolytes with dissimilar sizes of ions; a polymeric ion and a small counter ion. The movement of the small sodium (Na+) cation under heat gradient was explored in wet films and in solution. Because the ions could not cross the electrolyte-electrode junction, we propose the idea of ionic thermoelectric supercapacitor (ITESC), suitable for intermittent heat source.Nanofibrillated cellulose (NFC) has been used along with conducting polymers to realize the three dimensional conducting bulks as a TEG leg. NFC bulks were coated with conducting polymers as a first approach and later the mixture of (NFC & CP) was freeze-dried. The later approach resulted in mechanically flexible structures that were used as dual sensors for pressure and temperature based on the TE properties of the CP which can be utilized for electronic skin applications.The thesis shows new ways of utilizing waste heat using polymeric materials and points to a sensory application area, broadening the horizons of thermoelectricity.
The use of the layer-by-layer technology and low density networks of cellulose nanofibrils for pr... more The use of the layer-by-layer technology and low density networks of cellulose nanofibrils for preparing new materials for energy storage
The energy consumption in the world is continuously growing and the sources of energy are largely... more The energy consumption in the world is continuously growing and the sources of energy are largely dominated by fossil fuels. However, the resources of oil, gas and coal are diminishing in capacity. Moreover the CO2 emissions arising from their combustion is a great concern because it induces climate changes that threaten our habitat. There is a dire need to look for alternative sources of energies and to minimize losses of energy in our surroundings. Heat engines and turbines typically running with fossil energy have efficiencies of about 35%, i.e. 65% of the energy is lost in the form of heat. Low temperature heat (<200 ᴼC) is almost always wasted in power plants, industries, automobiles and household appliances. This is a huge resource that can be directly converted to electricity through the concept of thermoelectricity. Major challenges for heat to electricity conversion include finding the abundant materials with efficient thermoelectric (TE) conversion that can be mass prod...
A study has been made of the production of zinc oxide (ZnO) paper in a pilot paper machine. Bleac... more A study has been made of the production of zinc oxide (ZnO) paper in a pilot paper machine. Bleached sulphate softwood pulp (70%) and bleached sulphate hardwood pulp (30%) were corefined. Cationic ...
PaperCon 2019, held in Indianapolis, Indiana, USA, 5-8 May 2019, 2019
In moving towards a cellulose-based society, interdisciplinary effort is required as it is at thi... more In moving towards a cellulose-based society, interdisciplinary effort is required as it is at this interface that new ideas are found and can grow. New bio-based materials will play a key role but getting them into the marketplace is not always straightforward. Many options are available both for sourcing and for producing composite materials from wood-based cellulose and poly-lactic acid (PLA). Depending on how the material is processed, a multitude of properties can be generated. The main goal with this work was to attempt to reduce the research-to-market gap. This was done by testing a new way of working together where we bundled innovation-oriented projects and research-oriented projects around the theme of material experience. We then systematically worked with material demonstrators. In this article, we exemplify the results by focusing on one research-oriented project that did not at the outset have a market context and on one innovation-oriented project with clear market req...
Nordic Pulp and Paper Research Journal, 2012
Recent findings have shown that it is possible to use the Layer-by-Layer technique to create nano... more Recent findings have shown that it is possible to use the Layer-by-Layer technique to create nanofibrillated cellulose / polyethyleneimine interference films whose colour change with relative humidity. This study uses different optical models to describe spectral ellipsometry measurements data of interference films and how the film properties alter in dry and humid environments. The results indicate that water condensation initially is filling the surface pores within seconds whereas relaxation of the film to adjust to the added water is a slower process that reaches a steady state after »20 min. The maximum swelling ratio of the LbL films is almost independent of the number of layers within the film, but decreases considerably by crosslinking via heat treatment. The films show a distinct birefringence with optical axis perpendicular to the surface. Analysis of the moisture response with different optical models indicates that the films swell uniformly in the thickness direction wit...
Nordic Pulp and Paper Research Journal, 2004
Journal of Materials Chemistry A
Rolls of supercapacitor electrodes have successfully been produced on a pilot paper machine with ... more Rolls of supercapacitor electrodes have successfully been produced on a pilot paper machine with a novel material concept.
ACS Applied Polymer Materials
The global electrification of our society requires an enormous capacity of electrical energy stor... more The global electrification of our society requires an enormous capacity of electrical energy storage. This drives the demand for low-cost and sustainable solutions, where the electrode materials are key components. In the present work, all-organic supercapacitor electrodes have successfully been demonstrated to be produced on a pilot-scale paper machine, thereby showing the feasibility of large-scale production of “paper-based energy storage”. The material concept was based on activated charcoal from pyrolyzed coconut and cationized cellulose pulp, the latter having small amounts of electrostatically adsorbed PEDOT:PSS in order to create a conducting, percolating network. In a pre-trial lab experiment, it was evident that even small addition of 1 wt% PEDOT:PSS gave a large increase in capacitance compared to samples with only activated charcoal. In the pilot trials, the addition of carboxymethylated nanocellulose and/or carbon black was further investigated. The different additions ...