Thesis advisor: Dunwei Wang / Metal organic frameworks (MOFs) are a class of compounds that show promising potential for a variety of applications due to their uniformity, highly porous structure, lack of dead volume, and fine-tunability. One of these significant applications is in selective ion transport, which makes MOF films a uniquely good separatory material for dual-electrolyte setups, such as those being investigated with Mg-Br batteries. This research has important environmental and industrial ramifications, considering the various drawbacks associated with commercially available batteries such as the lithium-ion battery. The MOF investigated was Mg-MOF-74, which showed promising selective Mg2+ transport abilities. Both Mg-MOF-74 powder and films were synthesized via a vapor-assisted conversion process to maximize efficiency. To characterize the MOF, XRD and SEM imaging was used. This allowed us to gain a nuanced understanding of the material and its properties for further applications. / Thesis (BA) — Boston College, 2022. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: Departmental Honors. / Discipline: Chemistry.

Nanoparticle system research and characterization is the focal point of this research and dissertation. In the research presented here, magnetite, cobalt, and ferrite nanoparticle systems have been explored in regard to their magnetocaloric effect (MCE) properties, as well as for use in polymer composites. Both areas of study have potential applications across a wide variety of interdisciplinary fields. Magnetite nanoparticles have been successfully dispersed in a polymer. The surface chemistry of the magnetic nanoparticle proves critical to obtaining a homogenous and well separated high density dispersion in PMMA. Theoretical studies found in the literature have indicated that surface interface energy is a critical component in dispersion. Oleic acid is used to alter the surface of magnetite nanoparticles and successfully achieve good dispersion in a PMMA thin film. Polypyrrole is then coated onto the PMMA composite layer. The bilayer is characterized using cross-sectional TEM, cross-sectional SEM, magnetic characterization, and low frequency conductivity. The results show that the superparmagnetic properties of the as synthesized particles are maintained in the composite. With further study of the properties of these nanoparticles for real and functional uses, MCE is studied on a variety of magnetic nanoparticle systems. Magnetite, manganese zinc ferrite, and cobalt ferrite systems show significant broadening of the MCE and the ability to tune the peak temperature of MCE by varying the size of the nanoparticles. Four distinct systems are studied including cobalt, cobalt core silver shell nanoparticles, nickel ferrite, and ball milled zinc ferrite. The results demonstrate the importance of surface characteristics on MCE. Surface spin disorder appears to have a large influence on the low temperature magnetic and magnetocalorie characteristics of these nanoparticle systems.