Molecular Dynamics Simulations of GR/GO-Polyurethane/Polyurea Nanocomposites

Date

2024-9-02

Author

Sak, Berin

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Graphene/graphene oxide-polyurethane/polyurea nanocomposites hold great potential in industrial applications by combining the versatile attributes of polyurethane/polyurea (matrix) with enhanced properties of graphene and graphene oxide (nanofiller). Even though polyurethane and polyureas are widely used in industry and graphene/graphene oxide reinforcement is shown in many studies in literature, the interaction and reinforcement mechanism between the nanofiller and polymer matrix is not clearly demonstrated at the molecular level. This thesis aims to elucidate enhanced mechanical properties of these nanocomposites. Therefore, it focuses on the effect of different hard and soft segments in polyurethane/polyurea structures, oxygen ratios in the nanofiller, nanofiller concentration, and interfacial interactions. Various matrices alongside varying oxygen percentages of nanofiller are modeled and simulated for comprehensive analysis. Interaction energies at ab initio and classical levels, classical mixing energies, and Young’s modulus values are calculated using Density Functional Theory (DFT) and Molecular Dynamics (MD) simulation methods. It is demonstrated that the self-interaction and aggregation of the nanofiller are the main limitations. It can be mitigated by increasing nanofiller-polymer interaction through structural control and decreasing the self-interaction of the nanofiller via functional groups on the surface. Oxygen/carbon ratio, functional group type, and their distribution on the graphene oxide, and selection of polymers with appropriate polarity for this graphene oxide should be optimized to obtain a strong interaction between the nanofiller and the matrix. Therefore, the polarity of the polymer segments, oxygen content on the graphene oxide, and hydrogen bonding capabilities between the nanofiller and polymer are determined as the most critical parameters.

Subject Keywords

Molecular Dynamics Simulations, Graphene, Graphene Oxide, Polyurethane, Interaction Energy

URI

https://hdl.handle.net/11511/111330

Collections

Graduate School of Natural and Applied Sciences, Thesis