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- PostPurification of conjugated polymers. Better polymers through HPLC purification and Soxhlet extraction(2024) Öhberg, Jessika; Chalmers tekniska högskola / Institutionen för kemi och kemiteknik; Chalmers University of Technology / Department of Chemistry and Chemical Engineering; Giovannitti, Alexander; Westwood, MeganAbstract The purification of conjugated polymers, specifically the polymer D18, was investigated using the purification methods of Soxhlet extraction and High-Performance Liquid Chromatography (HPLC). The objective was to purify D18 from residual Pd impurities remaining from synthesis and fractionate the molecular weight for lower dispersity and higher molecular weights. This is crucial for conjugated polymers like D18, as with robust and effective purification methods, they have a prominent future as materials extensively used in organic electronic devices such as solar cells. The purification process has a significant impact on the polymer’s properties, influencing its electronic and optical performance which highlights the importance of standardized purification and reproducible results. The study demonstrates that while Soxhlet extraction was effective in removing low molecular weight fractions, HPLC proves to be superior in narrowing down the dispersity and reducing palladium (Pd) content for the polymer D18. The work also investigates the use of TOF-SIMS for measuring Pd content before and after purification by developing a calibration curve. Two palladium complexes, Pd(PPh3)4 and Pd2(dba)3 chloroform adduct, were along with the polymer P3HT used to create calibration curves, with Pd2(dba)3 showing better performance due to its solubility and stability. Challenges included potential contamination, suggesting the need for stricter environment protocols for sample handling. Calculating the Pd content from the calibration curves underscored the importance of a robust normalization technique to obtain absolute quantification. This research provides insights into purification methods that can enhance the performance of conjugated polymers in organic electronic applications and demonstrates the use of TOF-SIMS as an evaluation method of metal impurities. Keywords: Conjugated polymers, Purification, Soxhlet extraction, HPLC, TOFSIMS.
- PostLocal structure and dynamics of two novel metal-organic framework materials investigated with Raman spectroscopy and neutron scattering techniques(2024) Reinsfelt, David; Chalmers tekniska högskola / Institutionen för kemi och kemiteknik; Chalmers University of Technology / Department of Chemistry and Chemical Engineering; Weber, Daniel; Karlsson, MathsMetal-Organic Frameworks (MOFs) show a wide variety of new applications in areas such as energy storage, catalysis, sensor technology and drug delivery, due to their inherent porous structures and facile tunability. Some MOFs also show structural flexibility upon temperature variation, which opens up even more possibilities for applications. However, the local structure and dynamics, underpinning this flexibility, are often unclear. This thesis deals with a study of the local structure and dynamics of two newly discovered MOFs, namely La2(CPB) and Ce2(CPB), where CPB refers to the hexagon shaped hexatopic linker 1,2,3,4,5,6-hexakis(4- carboxyphenyl) benzene. La2(CPB), also called CTH-17, has previously proven to show gate opening effects under CO2 gas sorption measurements by drastically increase the adsorption after certain pressure values. Changes in the crystal structure in the form of twisted phenyl rings and stretching in the rod direction of the rod-shaped CTH-17 have also been observed when measured with SCXRD in 90 K, 300 K and 500 K. This study seeks to confirm these observed structure changes by studying local atomic vibrations, using Raman spectroscopy and inelastic neutron scattering (INS). The goal is not only to observe the static material structures before and after undergone the mentioned changes observed with SCXRD measurements, but also to observe the structural dynamics upon temperature variation. The samples were synthesized with a solvothermal synthesis method which yielded La2(CPB) and Ce2(CPB) as the majority phase with variable amounts of La or Ceformate as side phases. Both Raman and INS spectra of La2(CPB) and Ce2(CPB) show negligible differences, indicating that their local structure and dynamics are very similar. Room temperature Raman spectroscopy measurements of activated La2(CPB) and Ce2(CPB) samples show photoluminescence. The variable temperature Raman spectroscopy results show indications of DMF leaving the porous structures around 200-300 ◦C. Linearly shifting frequency trends with increased temperature is observed for several bands indicating thermal expansion, and a big irreversible shift at 300 ◦C is observed indicating a new structural phase. Indications of luminescence in combination with DMF leaving the structure is also observed. The similarities between La2(CPB) and Ce2(CPB) suggests that changing the metal ion nodes in this type of hexagonal shaped MOF from La to a similar metal such as Ce, does not alter the local structure and dynamics. The supposed observed thermal expansion and structural phase shift for both La2(CPB) and Ce2(CPB) could explain the gate opening effect during CO2 gas sorption measurements by showing that the porous structure changes upon increased temperature which can create more space for molecules to enter the pores.
- PostLocal structure and dynamics of two novel metal-organic framework materials investigated with Raman spectroscopy and neutron scattering techniques(2024) Reinsfelt, David; Chalmers tekniska högskola / Institutionen för kemi och kemiteknik; Chalmers University of Technology / Department of Chemistry and Chemical Engineering; Weber, Daniel; Karlsson, MathsMetal-Organic Frameworks (MOFs) show a wide variety of new applications in areas such as energy storage, catalysis, sensor technology and drug delivery, due to their inherent porous structures and facile tunability. Some MOFs also show structural flexibility upon temperature variation, which opens up even more possibilities for applications. However, the local structure and dynamics, underpinning this flexibility, are often unclear. This thesis deals with a study of the local structure and dynamics of two newly discovered MOFs, namely La2(CPB) and Ce2(CPB), where CPB refers to the hexagon shaped hexatopic linker 1,2,3,4,5,6-hexakis(4- carboxyphenyl) benzene. La2(CPB), also called CTH-17, has previously proven to show gate opening effects under CO2 gas sorption measurements by drastically increase the adsorption after certain pressure values. Changes in the crystal structure in the form of twisted phenyl rings and stretching in the rod direction of the rod-shaped CTH-17 have also been observed when measured with SCXRD in 90 K, 300 K and 500 K. This study seeks to confirm these observed structure changes by studying local atomic vibrations, using Raman spectroscopy and inelastic neutron scattering (INS). The goal is not only to observe the static material structures before and after undergone the mentioned changes observed with SCXRD measurements, but also to observe the structural dynamics upon temperature variation. The samples were synthesized with a solvothermal synthesis method which yielded La2(CPB) and Ce2(CPB) as the majority phase with variable amounts of La or Ceformate as side phases. Both Raman and INS spectra of La2(CPB) and Ce2(CPB) show negligible differences, indicating that their local structure and dynamics are very similar. Room temperature Raman spectroscopy measurements of activated La2(CPB) and Ce2(CPB) samples show photoluminescence. The variable temperature Raman spectroscopy results show indications of DMF leaving the porous structures around 200-300 ◦C. Linearly shifting frequency trends with increased temperature is observed for several bands indicating thermal expansion, and a big irreversible shift at 300 ◦C is observed indicating a new structural phase. Indications of luminescence in combination with DMF leaving the structure is also observed. The similarities between La2(CPB) and Ce2(CPB) suggests that changing the metal ion nodes in this type of hexagonal shaped MOF from La to a similar metal such as Ce, does not alter the local structure and dynamics. The supposed observed thermal expansion and structural phase shift for both La2(CPB) and Ce2(CPB) could explain the gate opening effect during CO2 gas sorption measurements by showing that the porous structure changes upon increased temperature which can create more space for molecules to enter the pores.
- PostSpectroscopic Investigation of Novel CARDIPY Derivatives(2024) Bair, Jessica Elizabeth; Chalmers tekniska högskola / Institutionen för kemi och kemiteknik; Chalmers University of Technology / Department of Chemistry and Chemical Engineering; Andréasson, Joakim; Benitez-Martin, Carlos
- PostSynthesis of functionalized glucose units for use in glycan assembly(2024) Sigfridsson, Gabriel; Chalmers tekniska högskola / Institutionen för kemi och kemiteknik; Chalmers University of Technology / Department of Chemistry and Chemical Engineering; Mårtensson, Jerker; Westman, Gunnar