​Abstract:  Hydrogels have attracted attention due to their interesting mechanical properties which makes them suitable for wide range of applications. Metallo-supramolecular hydrogels are particularly important due to their tenability. In this study, we report a simple method for synthesizing copper-containing polymer hydrogels made from nontoxic poly(methyl vinyl ether-alt-maleic anhydride) (PVM-MA) in the absence or presence of added carboxylate ligands: dicarboxylates, such as adipate and terephthalate, tricarboxylates, such as nitrilotriacetate (NTA) and citrate or tetracarboxylate such as ethylenediaminetetraacetic acid. Our copper hydrogels are wet precursors to a new family of amorphous porous materials, consisting of a metal-polycarboxylate backbone and carboxylate spacer ligands between polymer strands engineered via non-covalent interactions. Rheological measurements revealed that the mechanical stability of the hydrogels was enhanced by the addition of supplementary dicarboxylate ligands. We determined that the optimal ratio of polymer to dicarboxylate to Cu2+ was 10:4:2.5. Our scanning electron microscope (SEM) and cryo-SEM imaging and physical adsorption measurements revealed the formation of pores. 

The Brunauer–Emmett–Teller (BET) surface area of the dried hydrogels was tunable with the addition of supplementary dicarboxylate ligands. The BET surface area increased from 177.96 m2 g−1 in a dried hydrogel without added dicarboxylate to 646.9 and 536.4 m2 g−1 with the addition of adipate and terephthalate, respectively. Moreover, addition of dicarboxylate ligands increased the pore volume and CO2 gas adsorption capacity. Separation of CO2 from post-combustion flue gases is important for environmental and economic sustainability. Our copper-based hydrogel with dicarboxylate spacer ligands offers the possibility of a new material for post-combustion CO2. At commercial conditions (298 K and 1 bar), the hydrogel samples with adipate as a spacer ligand, showed notable promising CO2/N2 selectivity of 78.46 and a high CO2/CH4 selectivity reaching 26.09 at 1 bar. 

Furthermore, we investigated in detail the effect of metal ion on the rigidity and structure of hydrogels. A series of transition metal ions such as iron nitrate (Fe(NO3)3, aluminum nitrate (Al(NO3)3, zinc nitrate Zn(NO3)2, nickel nitrate Ni(NO3)2 and cobalt nitrate Co(NO3)2 were investigated for hydrogel formation. Scaling up of the synthesis of hydrogels was achieved using the filling machine which was used to fill silver hydrogels with antibacterial properties.

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• CONTACTLinda J. Sapolu

​ABSTRACT: Organic photovoltaics has emerged as a promising technology for electricity generation. The essential component in an organic solar cell is the bulk heterojunction absorber layer, typically a blend of an electron donor and an electron acceptor. Efforts have been made to design new materials such as donor polymers and novel acceptors to improve the power conversion efficiencies. Recently, non-fullerene acceptors have edged out the traditional fullerene acceptors. In general, these new acceptors provide low cost synthesis routes and provide tenability of their optoelectronic and electrochemical properties. Despite the huge efforts, still not much is known about the photopysical processes in these blends that limit the performance. In this respect, time-resolved spectroscopy such as transient absorption and time-resolved photoluminescence, can provide in-depth insight into the various (photo)physical processes in bulk heterojunction solar cell. 

In this thesis, PCE10 was used as donor polymer and paired with different non fullerene acceptors. More specifically, in the first part of this thesis the impact of the core structure (cyclopenta-[2,1-b:3,4-b']dithiophene (CDT) versus indacenodithiophene (IDTT)) of malononitrile (BM)-terminated acceptors, abbreviated as CDTBM and IDTTBM, on the photophysical characteristics of BHJ solar cells is reported. Using PCE10 as donor polymer, the IDTT-based acceptor achieves power conversion efficiencies of 8.4%, higher than those of the CDT-based acceptor (5.6%), because of a concurrent increase in short-circuit current and open-circuit voltage. Using (ultra)fast transient spectroscopy we demonstrate that reduced geminate recombination in PCE10:IDTTBM blends is the reason for the difference in short-circuit currents. External quantum efficiency measurements indicate that the higher energy of interfacial charge-transfer states observed for the IDTT-based acceptor blends is the origin of the higher open-circuit voltage. 

In the second part of this thesis, I report the impact of acceptor side chains on the photo-physical processes of BHJ solar cells using three different IDT-based acceptors, namely O-IDTBR, EH-IDTBR and O-IDTBCN blended with PCE10 as donor polymer. Power conversion efficiencies as high as 10 % were achieved. The transient absorption spectroscopy experiments provide insight into sub-picosecond exciton dissociation and charge generation which is followed by nanosecond triplet state formation in PCE10:O-DTBR and PCE10:EH-IDTBR blends, while in O-IDTBCN triplets are not observed. In addition, sensitive external quantum efficiency (EQE) measurements and photothermal deflection spectroscopy (PDS) were performed to extract the energy of interfacial charge transfer states. Time delayed collection field experiments (TDCF) were performed to address the charge carrier generation and examine its dependence on electric field. Finally, time-resolved photoluminescence spectroscopy has been conducted to study energy transfer processes in these polymer:non-fullerene acceptor blends.

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• CONTACTMazen E. Mero

​Abstract: Hydrothermal circulation at mid-ocean ridges can be traced by measuring chlorine (Cl) excess in erupted lavas when assimilation of hydrothermally altered crust by rising magma took place. Hydrothermal activity in the Red Sea is inferred in the Red Sea Deeps that host hot brines with hydrothermal sediments, but active hydrothermal vent fields have not be observed. The Red Sea Rift provides a unique opportunity to study assimilation of hydrothermally altered crust at an young, ultra-slow spreading ridge (maximum 1.6 cm yr-1 full spreading rate) by Cl, due to its high abundance in Cl in saline seawater (40-42‰, cf. 35‰ in open ocean water), in the (hot) brine pools (up to 270‰ salinity and 68°C) and in thick evaporite sequences that flank the young rift. Absolute chlorine concentrations (up to 1300 ppm) and Cl concentrations relative to minor or trace elements of similar mantle incompatibility (e.g., K, Nb) are much higher in Red Sea basalts than in basalts from average slow spreading ridges. Mantle Cl/Nb concentrations can be used to calculate the Cl-excess, above the magmatic Cl, that is present in the samples. Homogeneous within-sample Cl concentrations, the decoupling of Cl-excess from other trace elements and its independence of the presence of highly saline seafloor brines at the site of eruption indicate that Cl is not enriched at the seafloor. Instead we find basaltic Cl-excess to be spatially closely correlated with evidence of hydrothermal activity, suggesting that deeper assimilation of hydrothermal Cl is the dominant Cl-enrichment process. Proximity of samples to both evaporite outcrops and bathymetric signs of volcanism on the seafloor enhance Cl-excess in basalts. The basaltic Cl-excess can be used as a tracer - together with bathymetric maps and other indications for hydrothermal venting (hot brine pools, occurrence of metalliferous sediments) - to predict where active hydrothermal vent fields can be expected or inactive deposits may be located. Sites of particular interest for future hydrothermal research in the Red Sea Rift are the Mabahiss Deep, the Thetis-Hadarba-Hatiba Through and Shagara-Aswad-Erba Through (especially their large axial domes), and the Poseidon Deep. Older hydrothermal vent fields may be present at the Nereus and Suakin Deeps. These sites significantly increase the potential of hydrothermal vent field prospection in the Red Sea.

Bio: Dr. Froukje M. van der Zwan received her M.Sc. in geosciences with a specialization in geochemistry and petrology from the Vrije Universiteit Amsterdam, the Netherlands. There she worked on xenoliths from the Kaapvaal lithospheric mantle found in kimberlites (South Africa) and crystal size distribution studies of lavas from Merapi volcano (Indonesia). After her studies she moved to Kiel, Germany, where she performed her Ph.D. at GEOMAR Helmholtz Centre for Ocean Research Kiel, within the ‘Jeddah Transect Project’. The topic was Hydrothermal Activity at Slow-Spreading Mid-Ocean Ridges for which she developed a new method to measure basaltic chlorine with high precision on electron microprobes. She applied this method together with petrology and additional geochemical data to basalts from mid-ocean ridges with a focus on the Red Sea. The aim was to understand multiple processes at varying scales, from magmatism to hydrothermal circulation, prospection of submarine deposits and volcano morphology and she was involved in developing new geological models of the Red Sea. The current focus of her PostDoc project at the University of Kiel, for which she received a grant from the German Science Foundation, is on intraplate volcanism. She studies intraplate volcanism both on land, performing a project on volatiles as a potential cause for magmatism of the Cameroon Volcanic Line (West Africa) by geochemical studies of melt inclusions and in the ocean at e.g. the Bathymetrists Seamounts (Atlantic). She further works on continental breakup in the Red Sea and in the South China Sea. She has participated in 7 international research cruises, and lead the MSM70 expedition to the Bathymetrists Seamounts as chief scientist.

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• CONTACTKarema S. Alaseef

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• CONTACTKarema S. Alaseef