Caking-Inspired Cold Sintering of Plastic Supramolecular Films as Multifunctional Platforms

Caking of powder materials is undesired in various industries, and for thousands of years people are fighting against caking. Herein, the principle of caking is employed to create macroscopic plastic supramolecular films through a cold sintering process. A nanometer-sized, irregular coordinating cluster is first generated with a bulky head surfactant and multifunctional ligand, and the addition of metal ions immediately leads to amorphous white precipitates. Upon adsorbing moisture, a rearrangement of the molecules in the precipitates results in cold sintering, so that the particles in the precipitates grow into a transparent macroscopic film. The mechanical strength of the film is comparable to plastics, but allows welding and molding with finger at ambient temperature in moist environment. Mechanical tests suggest the supramolecular plastic does not fatigue even after several tens circles' remolding, indicating their superior material engineering capability. This strategy can be extended to different chemistries to fabricate films with different mechanical strength. Various functional components can be doped into the resultant films, rendering them a platform toward multifunctional materials, such as luminescent devices or sensors for pollution gases. The current strategy opens up a new vista in material science is expected.