Quantum Chemistry Simulations for Dynamic Network Polymers*

Conventional elastomers are crosslinked by covalent bonds. These covalent crosslinks create a permanent network, substantially increasing stiffness but decreasing stretchability. Alternatively, if polymers can be made with crosslinks that are strong, but able to break and reform, they will have similar stiffness benefits as the covalently crosslinked material without sacrificing stretchability, resulting in a high toughness material. Additionally, properties such as self-healing and solid-liquid transitions are also possible through this mechanism. In this talk, I will discuss a dynamic network polymer synthesized using organometallic coordination compounds as crosslinks, focusing on the behavior of the crosslinks as investigated using density functional theory. The potential energy surface of these crosslinking structures is reshaped as force is applied. The reaction paths of the structures are discovered using the growing string method, and are studied under increasing force. These studies yield force-dependent kinetics information that can be used to create a physics-based constitutive model of the material to compare with experimental mechanical tests.