Periodic Reporting for period 3 - WATUSO (Water Forced in Hydrophobic Nano-Confinement: Tunable Solvent System)
Reporting period: 2022-09-01 to 2024-02-29
Water is the sustainable solvent of excellence but its high polarity limits the solubility of non-polar compounds. Confinement of water in hydrophobic pores alters its hydrogen bonding structure and related properties such as dielectric constant and solvation power. How this special state of confined water can be rendered useful in chemical processes is hitherto underexplored. The original idea of this project is to modulate water solvent properties through hydrophobic nanoconfinement for practical applictions.
Pressure needs to be applied to force a heterogeneous mixture of poorly soluble molecules and water into hydrophobic nanopores of host material where the lowered polarity of water enhances mixing. Decompression after reaction causes expulsion of the solution from the pores and spontaneous demixing of reaction products as water returns to its normal polar state. Temporary dissolution enhancement during confinement is expected to be advantageous to chemical reaction and molecular storage. Development of dedicated hydrophobic nanoporous materials and research methodologies providing in situ characterization of confined water, solutes and host material using NMR, EIS, DRS, X-ray and neutron scattering under static and dynamic conditions are key aspects of this project. Nano-confined water opens new opportunities for green chemistry such as aqueous phase hydrogenation reactions which benefit from enhanced solubility of hydrogen, CO2 and poorly soluble organic compounds.
Unprecedented control in time and space over H2O solvation properties in a WATUSO system will enable new technologies with major scientific and societal impact. WATUSO will lead to new insights in water research and deliver new multidiagnostic characterization tools. WATUSO could revolutionize chemical manufacturing and gas storage (H2, CH4, CO2, etc.) and the concept could spill over to many more solvent-based processes. WATUSO will contribute significantly to a greener, more sustainable chemical industry and sustainable energy solutions.
Pressure needs to be applied to force a heterogeneous mixture of poorly soluble molecules and water into hydrophobic nanopores of host material where the lowered polarity of water enhances mixing. Decompression after reaction causes expulsion of the solution from the pores and spontaneous demixing of reaction products as water returns to its normal polar state. Temporary dissolution enhancement during confinement is expected to be advantageous to chemical reaction and molecular storage. Development of dedicated hydrophobic nanoporous materials and research methodologies providing in situ characterization of confined water, solutes and host material using NMR, EIS, DRS, X-ray and neutron scattering under static and dynamic conditions are key aspects of this project. Nano-confined water opens new opportunities for green chemistry such as aqueous phase hydrogenation reactions which benefit from enhanced solubility of hydrogen, CO2 and poorly soluble organic compounds.
Unprecedented control in time and space over H2O solvation properties in a WATUSO system will enable new technologies with major scientific and societal impact. WATUSO will lead to new insights in water research and deliver new multidiagnostic characterization tools. WATUSO could revolutionize chemical manufacturing and gas storage (H2, CH4, CO2, etc.) and the concept could spill over to many more solvent-based processes. WATUSO will contribute significantly to a greener, more sustainable chemical industry and sustainable energy solutions.
Synthesis and characterization of WATUSO host materials:
Multiple types of nanoporous materials for investigating confined water have been synthesized, characterized and used in water confinement studies: zeolites, covalent organic frameworks, layered double hydroxides, organic polymers and POSiSils. (Journal Of The American Chemical Society; 2020; Vol. 142; iss. 47; pp. 20107 - 20116; Chemistry-A European Journal; 2021; Vol. 27; iss. 64; pp. 15944 - 15953; Materials Horizons; 2021; Vol. 8; iss. 9; pp. 2576 - 2583; Materials Horizons; 2020; Vol. 7; iss. 6; pp. 1528 - 1532).
Scientific breakthroughs:
- Water-alcohol mixtures confined in zeolite nanopores were found to interact in an peculiar way with the pore walls. Alcohol molecules were observed to make hydrogen bonds to Si-O-Si siloxane oxygen atoms of the zeolite framework. On oxide materials this newly discovered universal mechanism of adsorption of molecules capable of H-bonding co-exists with the traditionally accepted physisorption mechanisms.
- Enhanced nucleation and growth of clathrate hydrates from water confined in hydrophobic nanopores. Intrusion of water into hydrophobic nanopores with suitable pore wall functionality enables clathrate formation of H2 and CH4 and C2H6 at reduced pressure and temperature. (Journal of Materials Chemistry A; 2021; Vol. 9; iss. 38; pp. 21835 - 21844; Energy Storage Materials; 2021; Vol. 41; pp. 69 - 107 )
- Confinement of water in hydrated organic polymers. Hydrated carbomers are used in a score of applications (cosmetics, paints, hydrogels, …) for thickening, suspending, dispersing and stabilizing products. Using high field 1H NMR spectroscopy, insight in the process of water incorporation, polymer unfolding and hydration was obtained. This offered molecular level view on the impact of nanoconfined water incorporation on the rheology of hydrogels, allowing to improve mixing technology, shorten mixing time and reduce structural damage to the carbomer.(Rsc Advances; 2022; Vol. 12; iss. 13; pp. 7830 - 7834).
WATUSO applications:
- Water production from water vapor contained in atmospheric air is a possible solution to fulfil human water needs in case of local water scarcity and climate change. The WATUSO approach involves water vapor adsorption in porous thermo-responsive hydrophilicity switching polymers which turn hydrophobic and leak water upon solar heating. Energy consumption estimates of existing and emerging water-from-air technologies including the WATUSO system enabled to identify of optimal water-from-air technology depending on the climate, relative humidity, and temperature profiles. (iScience. 2021 Nov 19; 24(11): 103266; Environ. Sci.: Water Res.Technol. 2020, 6, 2016).
- Enhanced Nucleation and growth of clathrate phases by confinement under pressure of water and gases such H2 and CH4 and C2H6 in hydrophobic nanopores with suitable pore wall functionality. Enhanced stability enabling reversible uptake and release of small molecules while preserving the ice structure in the cycle are obtained by confinement. (Energy Storage Materials; 2021; Vol. 41; pp. 69 - 107; )
Multiple types of nanoporous materials for investigating confined water have been synthesized, characterized and used in water confinement studies: zeolites, covalent organic frameworks, layered double hydroxides, organic polymers and POSiSils. (Journal Of The American Chemical Society; 2020; Vol. 142; iss. 47; pp. 20107 - 20116; Chemistry-A European Journal; 2021; Vol. 27; iss. 64; pp. 15944 - 15953; Materials Horizons; 2021; Vol. 8; iss. 9; pp. 2576 - 2583; Materials Horizons; 2020; Vol. 7; iss. 6; pp. 1528 - 1532).
Scientific breakthroughs:
- Water-alcohol mixtures confined in zeolite nanopores were found to interact in an peculiar way with the pore walls. Alcohol molecules were observed to make hydrogen bonds to Si-O-Si siloxane oxygen atoms of the zeolite framework. On oxide materials this newly discovered universal mechanism of adsorption of molecules capable of H-bonding co-exists with the traditionally accepted physisorption mechanisms.
- Enhanced nucleation and growth of clathrate hydrates from water confined in hydrophobic nanopores. Intrusion of water into hydrophobic nanopores with suitable pore wall functionality enables clathrate formation of H2 and CH4 and C2H6 at reduced pressure and temperature. (Journal of Materials Chemistry A; 2021; Vol. 9; iss. 38; pp. 21835 - 21844; Energy Storage Materials; 2021; Vol. 41; pp. 69 - 107 )
- Confinement of water in hydrated organic polymers. Hydrated carbomers are used in a score of applications (cosmetics, paints, hydrogels, …) for thickening, suspending, dispersing and stabilizing products. Using high field 1H NMR spectroscopy, insight in the process of water incorporation, polymer unfolding and hydration was obtained. This offered molecular level view on the impact of nanoconfined water incorporation on the rheology of hydrogels, allowing to improve mixing technology, shorten mixing time and reduce structural damage to the carbomer.(Rsc Advances; 2022; Vol. 12; iss. 13; pp. 7830 - 7834).
WATUSO applications:
- Water production from water vapor contained in atmospheric air is a possible solution to fulfil human water needs in case of local water scarcity and climate change. The WATUSO approach involves water vapor adsorption in porous thermo-responsive hydrophilicity switching polymers which turn hydrophobic and leak water upon solar heating. Energy consumption estimates of existing and emerging water-from-air technologies including the WATUSO system enabled to identify of optimal water-from-air technology depending on the climate, relative humidity, and temperature profiles. (iScience. 2021 Nov 19; 24(11): 103266; Environ. Sci.: Water Res.Technol. 2020, 6, 2016).
- Enhanced Nucleation and growth of clathrate phases by confinement under pressure of water and gases such H2 and CH4 and C2H6 in hydrophobic nanopores with suitable pore wall functionality. Enhanced stability enabling reversible uptake and release of small molecules while preserving the ice structure in the cycle are obtained by confinement. (Energy Storage Materials; 2021; Vol. 41; pp. 69 - 107; )
Hydrogenation reactions and gas storage are among the most straightforward showcase applications gaining from improved solvent properties of confined water. Partial intrusion conditions, leaving the smallest pores unfilled, are expected to be beneficial for maximizing the gas-liquid interphase. Clever design of pore architecture and surface chemistry will enable to maximize contact between intruded water and gas molecules adsorbed in a hierarchical network of pores. Among all possible gaseous molecules to be investigated, some emerge of utmost importance: H2, CO2 and CH4. Enhanced hydrogen and CO2 dissolution in water is of direct interest to electro- and chemo catalysis and (photo)electrochemical solar fuel devices. Efficient H2 and CH4 storage remains a grand scientific challenge. Hydrophobic materials filled with water with low dielectric constant are promising media for gas storage. Hydrogenation catalysis in water can gain tremendously from enhanced hydrogen dissolution, with production of renewables by aqueous catalytic hydrogenation of biomass carbohydrate derivatives as prominent envisaged application.