Mesoscale filament assembly into mechanically interlocked structuresAlfred Crosby

Mechanical interlocking, including braiding and weaving, of long, slender filaments allows materials structures to possess property combinations that cannot be achieved in any other manner. Unique balances of flexibility and stiffness, along with strength, conductivity, and transport control, have made structures such as ropes, weaves, and knits ubiquitous in all aspects of modern society. Daily functions and engineering feats would not be possible without such structures. However, the ability to take advantage of mechanically interlocked topologies on small, micron or smaller, scales is limited due to current materials and manufacturing methods. We discuss the development of responsive polymer and polymer-nanoparticle materials that undergo spatiotemporal transformations to enable the creation of interlocked structures. We discuss the integration of multiple fields and driving forces, including elastic, interfacial, gravitational, poroelastic, chemical, and electrical. The combination of fields allows kinematic transformations of neighboring filaments to be coordinated spatially and temporally to achieve linking. We demonstrate the ability to create irreversible and reversible structures, and we describe the mechanical characterization of individual filaments and assembled structures to demonstrate their potential functionality. The realization of sub-micron mechanically interlocked structures will lead to advances in wireless communication, medical devices, and pathways for sustainable, circular materials engineering.