Rocha, Brunno Carvalho
Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Chemical Engineering.
DISSERTATION ABSTRACT:
Self-assembly is a fundamental process in nature that refers to the spontaneous organization of individual molecules into larger and more complex structures. In recent decades, self-assembly has gained increased importance in materials science, as it enables the production of functional materials with tailored properties using carefully designed particles as building blocks. A promising direction within this realm of research involves the use of lobed colloidal particles to produce porous biomaterials with a wide range of practical applications, including tissue regeneration and catalysis. Given the growing interest in this topic, my dissertation work is mainly focused on conducting modeling and simulation studies on the behavior of lobed particles undergoing self-assembly. More specifically, I investigated the dynamics of lobed colloid particles and explored the influence of varying the particle shapes and environmental factors as they relate to the morphological properties of the final structures. To achieve this goal, I performed molecular dynamics (MD) simulations of a diverse set of lobed particles under different conditions. I considered distinct design variables, including the number, size, and positioning of lobes on the particle surface, allowing for a detailed exploration of the impact of particle characteristics on the properties of self- assembled structures. In these systems, self-assembly is mediated by attractive interactions between the lobes of different particles. For this reason, I investigated the role of distinct types of interactions in determining the morphology and porosity of the self-assembled structures by altering both their strength and nature (uncharged, heterogeneously-charged, homogeneously-charged or functionalized) in different simulations.
As a result of this thorough analysis, I identified the most favorable particle designs and system conditions that promote the creation of large-scale porous structures with tailored characteristics. In addition to studies focused on lobed particles, I also performed simulations of systems comprised of metal-organic frameworks (MOFs) and biologically relevant organic analytes. Several MOFs present the ability to convert chemical interactions into electrical signals, making them promising materials for electroanalytical applications. In the final part of my dissertation, I employed MD simulations to elucidate how organic analytes interact with MOFs at the atomic level. This work provided a deeper insight into how different molecular interactions dictate the adsorption of organic molecules on conductive MOFs and give rise to distinct electrochemical responses. In conclusion, this dissertation highlights the significance of self-assembly phenomena for the development of novel biomaterials, particularly within the context of lobed colloidal particles and MOFs. The utilization of MD simulations allowed investigations of the self-assembly processes at a level of detail that is often challenging to achieve through traditional experimental methods. These simulations also provided additional knowledge on the intricacies that influence the creation of tailored porous biomaterials from lobed particles and elucidated the different ways that organic molecules interact with MOFs during adsorption.