A computational approach to fundamentally understand blending thermodynamics between polymers and single-wall carbon nanotubes

Abstract

Carbon nanotubes (CNTs) have been known as superior reinforcement fillers for composite materials because they exhibit a combination of multiple exceptional properties. Previous work has demonstrated that low loadings of CNTs in matrix materials can lead to a significant enhancement of mechanical properties. High reinforcement efficiency is dependent upon good dispersion quality and exfoliation of the CNT in the matrix material. While the strong inter-tube Van der Waals interactions make the uniform distribution of CNT hard to accomplish. Previous work in the MINUS Lab has shown that non-solvent induced phase separation can drive the formation of CNT-polymer blended phase with extraordinary dispersion quality. This process gives rise to a potential tool for promoting dispersion and blending in the nanocomposite for various combination of materials. However, the fundamental understanding for the mechanisms driving dispersion in this phase separation remains unclear. This is due to the 'invisible' nature of the system (due to opacity) and difficulty monitoring the thermodynamics in the system. For this reason, a computational approach is needed to assist with understanding the mechanism behind the phase separation phenomenon and inherent polymer-CNT interaction. Atomic- and meso-scale models were constructed and successfully reproduced the phenomena observed in the experimental work. Further experimental validation will be performed to quantitatively confirm the feasibility of the computational model. For this dissertation work, the thermodynamic profile and conformation of each component will be tracked in the verified simulation model, and a lattice-like 'Flory-Huggins' model for polymer and CNT will be built by using the result from simulation work.--Author's abstract