Abstract
Self-unfolding items provide a practical convenience, wherein ring-like frames are contorted into a state of equilibrium and subsequently pop up’ or deploy when perturbed from a folded structure. Can the same process be exploited at the molecular scale? At the limiting scale is a closed chain of single atoms, used here to investigate the limits of stability of such folded ring structures via full atomistic molecular dynamics. Carbyne is a one-dimensional carbon allotrope composed of sp-hybridized carbon atoms. Here, we explore the stability of idealized carbyne loops as a function of chain length, curvature, and temperature, and delineate an effective phase diagram between folded and unfolded states. We find that while overall curvature is reduced, in addition to torsional and self-adhesive energy barriers, a local increase in curvature results in the largest impedance to unfolding.
Highlights
A clever trick by product designers is self-unfolding structures such as collapsible laundry hampers and ‘pop-up’ tents
Root mean square deviation Example snapshots of an unfolding loop are given in Figure 3, along with the associated root mean square deviation (RMSD) plot
The RMSD is defined as the spatial difference between two molecular structures: rffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi where N denotes the number of atoms, r(t) denotes the position of each atom in the structure at time t, and r0 denotes the positions for the initial three-loop structure
Summary
A clever trick by product designers is self-unfolding structures such as collapsible laundry hampers and ‘pop-up’ tents. We focus on the smallest possible unfolding system - a closed chain of carbon atoms - to investigate the limits of stability at the atomistic scale Insights from such structures can be applied to more complex macromolecular systems, such as responsive polymer [5,6] or protein-based materials [7,8,9,10]. This 1D carbon structure has caused recent interest due to its novel electron transport and the prospect of being components in atomistic scale circuits [13,14], as well as recent synthesis of long chains [15,16,17,18,19]. Considered here is a system of isolated closed-loop carbyne (Figure 1b) to explore the stability of a folded three-loop geometry (Figure 1c)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
