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| 2. |
- Cortes Ruiz, Maria F., et al.
(författare)
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Structure-properties relationships of defined CNF single-networks crosslinked by telechelic PEGs
- 2024
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Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 339
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Tidskriftsartikel (refereegranskat)abstract
- The high structural anisotropy and colloidal stability of cellulose nanofibrils' enable the creation of self-standing fibrillar hydrogel networks at very low solid contents. Adding methacrylate moieties on the surface of TEMPO oxidized CNFs allows the formation of more robust covalently crosslinked networks by free radical polymerization of acrylic monomers, exploiting the mechanical properties of these networks more efficiently. This technique yields strong and elastic networks but with an undefined network structure. In this work, we use acrylate-capped telechelic polymers derived from the step-growth polymerization of PEG diacrylate and dithiothreitol to crosslink methacrylated TEMPO-oxidized cellulose nanofibrils (MATO CNF). This combination resulted in flexible and strong hydrogels, as observed through rheological studies, compression and tensile loading. The structure and mechanical properties of these hydrogel networks were found to depend on the dimensions of the CNFs and polymer crosslinkers. The structure of the networks and the role of individual components were evaluated with SAXS (Small-Angle X-ray Scattering) and photo-rheology. A thorough understanding of hybrid CNF/polymer networks and how to best exploit the capacity of these networks enable further advancement of cellulose-based materials for applications in packaging, soft robotics, and biomedical engineering.
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| 3. |
- Gao, Ying, et al.
(författare)
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Gradience Free Nanoinsertion of Fe3O4 into Wood for Enhanced Hydrovoltaic Energy Harvesting
- 2023
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 11:30, s. 11099-11109
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Tidskriftsartikel (refereegranskat)abstract
- Hydrovoltaic energy harvesting offers the potential to utilize enormous water energy for sustainable energy systems. Here, we report the utilization and tailoring of an intrinsic anisotropic 3D continuous microchannel structure from native wood for efficient hydrovoltaic energy harvesting by Fe3O4 nanoparticle insertion. Acetone-assisted precursor infiltration ensures the homogenous distribution of Fe ions for gradience-free Fe3O4 nanoparticle formation in wood. The Fe3O4/wood nanocomposites result in an open-circuit voltage of 63 mV and a power density of ∼52 μW/m2 (∼165 times higher than the original wood) under ambient conditions. The output voltage and power density are further increased to 1 V and ∼743 μW/m2 under 3 suns solar irradiation. The enhancement could be attributed to the increase of surface charge, nanoporosity, and photothermal effect from Fe3O4. The device exhibits a stable voltage of ∼1 V for 30 h (3 cycles of 10 h) showing good long-term stability. The methodology offers the potential for hierarchical organic-inorganic nanocomposite design for scalable and efficient ambient energy harvesting.
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| 4. |
- Gao, Ying, et al.
(författare)
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Olive Stone Delignification Toward Efficient Adsorption of Metal Ions
- 2021
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Ingår i: Frontiers in Materials. - : Frontiers Media SA. - 2296-8016. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Olive stone is an important biomaterial waste product generated in large amount. As a lignocellulose material, olive stone could be a sustainable resource for biosorbents. In this work, olive stone powder delignification using sodium chlorite (NaClO2) was performed to enhance metal ion adsorption capacity. The influence of the treatment on olive stone powder physical-chemical properties was studied, including specific surface area, surface chemistry, morphology, etc. The white, delignified olive stone powder was applied for metal ions (Fe3+, Cu2+, and Zn2+) adsorption. Olive stone delignification not only increases the accessibility of the olive stone powder but also broadens the applications to materials design with optical functions by the generation of a white powder.
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| 5. |
- Gao, Ying, et al.
(författare)
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Scalable hierarchical wood/ZnO nanohybrids for efficient mechanical energy conversion
- 2023
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Ingår i: Materials & design. - : Elsevier BV. - 0264-1275 .- 1873-4197. ; 226
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Tidskriftsartikel (refereegranskat)abstract
- Owing to the hierarchical structure, easy multi-functionalization and favorable mechanical properties, wood could harvest electricity from mechanical energy through piezoelectric behavior. In this work, a scalable method to synthesize wood/ZnO composite with multilayered ZnO morphologies is reported for efficient mechanical energy conversion. The synthesis includes charged wood template fabrication, precursor infiltration, and ZnO hydrothermal growth, resulting in controlled ZnO morphologies and distributions while maintaining the hierarchical structure of the wood. Stereo-digital image correlation (stereo-DIC) investigated the relationship between deformation and piezoelectric performance, which revealed the homogeneous distribution of multilayered ZnO enhance piezoelectric performance. The output voltage of wood/ZnO was 1.5 V under periodic mechanical compression (8–10 N) for 300 cycles, while the output current was 2.91 nA. The scalable synthesis strategy and piezoelectric performance are significant for the design of advanced wood nanocomposites for sustainable and efficient energy conversion systems.
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| 6. |
- Garemark, Jonas, et al.
(författare)
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Advancing Hydrovoltaic Energy Harvesting from Wood through Cell Wall Nanoengineering
- 2023
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Ingår i: Advanced Functional Materials. - : John Wiley and Sons Inc. - 1616-301X .- 1616-3028. ; 33:4
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Tidskriftsartikel (refereegranskat)abstract
- Converting omnipresent environmental energy through the assistance of spontaneous water evaporation is an emerging technology for sustainable energy systems. Developing bio-based hydrovoltaic materials further pushes the sustainability, where wood is a prospect due to its native hydrophilic and anisotropic structure. However, current wood-based water evaporation-assisted power generators are facing the challenge of low power density. Here, an efficient hydrovoltaic wood power generator is reported based on wood cell wall nanoengineering. A highly porous wood with cellulosic network filling the lumen is fabricated through a green, one-step treatment using sodium hydroxide to maximize the wood surface area, introduce chemical functionality, and enhance the cell wall permeability of water. An open-circuit potential of ≈140 mV in deionized water is realized, over ten times higher than native wood. Further tuning the pH difference between wood and water, due to an ion concentration gradient, a potential up to 1 V and a remarkable power output of 1.35 µW cm−2 is achieved. The findings in this study provide a new strategy for efficient wood power generators. © 2022 The Authors.
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| 7. |
- Garemark, Jonas
(författare)
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Integrated Cellulosic Wood Aerogel Structures
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Highly porous aerogels based on renewable materials that possess structural functionality are appealing for sustainable energy regulation and harvesting. Achieving structural anisotropy provides advantageous directional diffusion and mechanical strength, however, introduces great engineering challenges, such as complex, costly, and time-consuming processing. Direct use of wood, where nanocellulose is favorably orientated, offers the opportunity of forming low-cost, scalable, and eco-friendly aerogels.This thesis explores a new type of nanostructured wood material design by filling the empty wood space with cellulosic aerogel structures based on its intrinsic biopolymers. The structure control is achieved through selective reassembly of the cell wall nanocomponents by cell wall partial dissolution and regeneration. The resultant structures, named integrated wood aerogels, show a unique combination of high specific surface area and strength due to partial retention of the wood hierarchical structure and formation of mesoporous nanofibrillated networks occupying the lumen. Different chemical systems are investigated, including DMAc/LiCl, ionic liquid (IL), and aqueous NaOH, and the processing-structure-property relationships are investigated. DMAc/LiCl is successfully used as proof of concept for integrated wood aerogel formation, but moisture sensitivity and toxicity of the system hinder further development. The IL [MTBD][MMP] is developed to solve the issues and to improve the structure control in cell wall dissolution and regeneration. An aqueous NaOH system advances the integrated cellulosic wood aerogel preparation further, considering low cost and greener chemistry. Wood composition, lignin in particular, is critical to the processing and final properties of the integrated wood aerogel. The influence of lignin content is investigated based on IL and NaOH systems. The influence of processing (such as chemical system, time and temperature) on the structure and properties (e.g. porosity, specific surface area, mechanical performance, thermal conductivity and charge density) of the aerogels are studied. Ascribing to the structure-property profile, the application of the integrated aerogel for efficient thermal insulation is demonstrated. Inspired by the water uptake in plants, high-performing pH-responsive wood power generators are formed based on water evaporation-induced electricity. The integrated aerogel structure greatly increases the solid/liquid interphase while allowing excellent mass diffusion.The methodologies presented in this thesis for selective nanoscale reassembly of the wood cell wall pave the way for advanced wood nanostructure control. The integrated wood aerogel structure reported here provides a universal material platform for advanced material design, such as a self-sustaining wood power generator. The facile and scalable processing contribute toward sustainable high-performing bioaerogels which can compete with fossil-based materials.
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| 8. |
- Garemark, Jonas, et al.
(författare)
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Nanostructurally Controllable Strong Wood Aerogel toward Efficient Thermal Insulation
- 2022
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Ingår i: ACS Applied Materials & Interfaces. - : American Chemical Society (ACS). - 1944-8252 .- 1944-8244. ; 14:21, s. 24697-24707
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Tidskriftsartikel (refereegranskat)abstract
- Eco-friendly materials with superior thermal insulation and mechanical properties are desirable for improved energy- and space-efficiency in buildings. Cellulose aerogels with structural anisotropy could fulfill these requirements, but complex processing and high energy demand are challenges for scaling up. Here we propose a scalable, nonadditive, top-down fabrication of strong anisotropic aerogels directly from wood with excellent, near isotropic thermal insulation functions. The aerogel was obtained through cell wall dissolution and controlled precipitation in lumen, using an ionic liquid (IL) mixture comprising DMSO and a guanidinium phosphorus-based IL [MTBD][MMP]. The wood aerogel shows a unique structure with lumen filled with nanofibrils network. In situ formation of a cellulosic nanofibril network in the lumen results in specific surface areas up to 280 m2/g and high yield strengths >1.2 MPa. The highly mesoporous structure (average pore diameter 20 nm) of freeze-dried wood aerogels leads to low thermal conductivities in both the radial (0.037 W/mK) and axial (0.057 W/mK) directions, showing great potential as scalable thermal insulators. This synthesis route is energy efficient with high nanostructural controllability. The unique nanostructure and rare combination of strength and thermal properties set the material apart from comparable bottom-up aerogels. This nonadditive synthesis approach is believed to contribute significantly toward large-scale design and structure control of biobased aerogels.
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| 9. |
- Garemark, Jonas, et al.
(författare)
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Strong, Shape-Memory Aerogel via Wood Cell Wall Nanoscale Reassembly
- 2023
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 17:5, s. 4775-4789
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Tidskriftsartikel (refereegranskat)abstract
- Polymer shape-memory aerogels (PSMAs) are prospects in various fields of application ranging from aerospace to biomedicine, as advanced thermal insulators, actuators, or sensors. However, the fabrication of PSMAs with good mechanical performance is challenging and is currently dominated by fossil-based polymers. In this work, strong, shape-memory bio-aerogels with high specific surface areas (up to 220 m2/g) and low radial thermal conductivity (0.042 W/mK) were prepared through a one-step treatment of native wood using an ionic liquid mixture of [MTBD]+[MMP]−/DMSO. The aerogel showed similar chemical composition similar to native wood. Nanoscale spatial rearrangement of wood biopolymers in the cell wall and lumen was achieved, resulting in flexible hydrogels, offering design freedom for subsequent aerogels with intricate geometries. Shape-memory function under stimuli of water was reported. The chemical composition and distribution, morphology, and mechanical performance of the aerogel were carefully studied using confocal Raman spectroscopy, AFM, SAXS/WAXS, NMR, digital image correlation, etc. With its simplicity, sustainability, and the broad range of applicability, the methodology developed for nanoscale reassembly of wood is an advancement for the design of biobased shape-memory aerogels.
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| 10. |
- Garemark, Jonas, et al.
(författare)
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Top-Down Approach Making Anisotropic Cellulose Aerogels as Universal Substrates for Multifunctionalization
- 2020
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Ingår i: ACS Nano. - : AMER CHEMICAL SOC. - 1936-0851 .- 1936-086X. ; 14:6, s. 7111-7120
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Tidskriftsartikel (refereegranskat)abstract
- Highly porous, strong aerogels with anisotropic structural properties are of great interest for multifunctional materials for applications including insulators in buildings, filters for oil cleanup, electrical storage devices, etc. Contemporary aerogels are mostly extracted from fossil resources and synthesized from bottom-up techniques, often requiring additional strategies to obtain high anisotropy. In this work, a universal approach to prepare porous, strong, anisotropic aerogels is presented through exploiting the natural hierarchical and anisotropic structure of wood. The preparation comprises nanoscale removal of lignin, followed by dissolution-regeneration of nanofibers, leading to enhanced cell wall porosity with nanofibrillated networks occupying the pore space in the cellular wood structure. The aerogels retain structural anisotropy of natural wood, exhibit specific surface areas up to 247 m(2)/g, and show high compression strength at 95% porosity. This is a record specific area value for wood aerogels/foams and even higher than most cellulose-based aerogels for its assigned strength. The aerogel can serve as a platform for multifunctional composites including scaffolds for catalysis, gas separation, or liquid purification due to its porous matrix or as binder-free electrodes in electronics. To demonstrate the multifunctionality, the aerogels are successfully decorated with metal nanoparticles (Ag) and metal oxide nanoparticles (TiO2) by in situ synthesis, coated by the conductive polymer (PEDOT:PSS), and carbonized to yield conductive aerogels. This approach is found to be a universal way to prepare highly porous anisotropic aerogels.
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