Experimental and computational studies of materials decomposition

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University of Alabama Libraries

Hydrogen enriched fuels offer a broad range of thermo-physical and chemical properties that are desirable for combustion reactions. In this work, a eutectic mixture of ammonia borane and methylamine borane that demonstrates improved solubility in polar solvents compared to the single constituents was prepared and characterized. Ignition and burn of the amine borane eutectic mixture were characterized using high framerate imaging and emission spectroscopy. The solubility of ammonia borane, methylamine borane, dimethylamine borane, trimethylamine borane, and tert-butylamine borane in different solvents was measured and modeled using the COSMO-RS utility in ADF2016 and the self-consistent reaction field (SCRF) method. The enthalpy of solution was experimentally determined for ammonia borane, methylamine borane, dimethylamine borane, and the ammonia borane/methylamine borane eutectic in different solvents.In addition to characterization of known hydrogen storage materials, new high energy hydrogen storage materials were computationally designed. The energetics and decomposition pathways for novel carbon, nitrogen, silicon, and phosphorus centered substituted amine borane hydrogen storage materials were modeled using composite correlated molecular orbital theory at the G3MP2 level, and the amounts of different species as a function of temperature were predicted using Gibbs free energy minimization. Theoretical models of decomposition reactions are also important for perfluorocarbon synthesis and polymer property modification. Safe and effective direct fluorination of compounds can reduce cost of synthesizing fluorinated compounds as well as potentially improving processability. The thermodynamics for direct fluorination of tetrafluoroethylene and the role of hexafluoropropylene oligomers in reducing explosions were predicted. In addition, high energy radiation from γ-rays or lasers can be used to improve the properties and processability of polymers such as a tetrafluoroethylene/perfluoro(methyl vinyl ether) copolymer or poly(vinyl alcohol) potentially leading to reduces bacterial contamination in packaging for pharmaceutical and food. A computational model for decomposition of a tetrafluoroethylene/perfluoro(methyl vinyl ether) copolymer was developed using composite correlated molecule orbital theory corrected density functional theory calculations. The mechanism of infrared laser ablation of γ-irradiated poly(vinyl alcohol) to produce water and ketone species was studied computationally using composite correlated molecular orbital theory.

Electronic Thesis or Dissertation
Chemical engineering, Chemistry, Computational chemistry