(271b) Dynamics of Semi-Flexible, Self-Interacting Sheets in Shear Flow

Graphene is a versatile material with excellent mechanical and electronic properties, making it useful in various applications such as electronics and medicine. Furthermore, a single graphene sheet can be used to construct its 0D (buckminsterfullerene), 1D (carbon nanotube), or 3D (graphite) analogs, each of which have their own applications. Other 2D materials such as graphene oxide, transition metal dichalcogenides, and, more recently, synthetic 2D polymers have their own range of applications, expanding the design space for 2D materials considerably. Shear exfoliation of graphite is an inexpensive, scalable method for producing single-layer graphene suspensions, which can be processed further for desired applications. However, there is a knowledge gap in the understanding of 2D materials, especially in comparison to their 1D analogs.

Here, we expand upon previous work studying the buckling of athermal sheets in shear flow by adding short-ranged self-interactions to simulate, for example, pi-pi interactions between graphene sheets. We present a dimensionless group relating the strength of interactions to that of shear. By varying the interaction strength and bending rigidity relative to shear, we find a rich landscape with regards to both the shape and rotational dynamics of the sheets, with strong, non-monotonic dependencies on the interaction strength. These interaction-dependent dynamics result in shear-thinning into shear-thickening regimes, which have been previously observed in dilute graphene suspensions. By understanding the dynamics of single sheets with self-interactions, we lay the foundation for comprehending dilute suspensions, and ultimately, the behavior and interaction of multiple sheets in shear. This knowledge is critical for predicting suspension properties and developing solution processing protocols.