Controlled Growth and Tailorable Functionalization of Two-Dimensional Supramolecular Films

Two-dimensional (2D) supramolecular materials have gained increasing attention due to their intrinsic dynamic and adaptive features, yet intractable growth process and functionalization severely impede their further advances. Here, we report a reaction-mediated modular and interfacial self-assembly strategy that enables both controlled growth and tailorable functionalization of layer-stacked 2D supramolecular films. The self-assembling monomers are generated in situ from water-soluble trishydrazide and boronic acid-containing aldehydes through the formation of hydrazone bonds. Directed by hydrophobic interactions, these hydrazone-based monomers self-assemble at hydrophilichydrophobic interfaces, giving rise to 2D supramolecular polymers (2DSPs) stabilized by in-plane hydrogen bonding between boronic acid groups. Over time, free-standing supramolecular films comprising multilayer 2DSPs are formed, with their growth rate dictated by the kinetics of hydrazone formation. Moreover, films with varying thickness can be grown on diverse substrates, producing tunable structural colors. Importantly, because of the modularity of our self-assembly system, various chemical moieties can be readily incorporated into the films by using different aldehyde-decorated modules, enabling the resultant films with tailorable chemical functionalities without perturbing the self-assembly behavior. Furthermore, by virtue of a sequential growth of distinct functional layers, supramolecular films with layer-resolved chemical properties are created. Such a reaction-mediated modular and interfacial self-assembly strategy may boost the development of sophisticated 2D supramolecular materials with defined dimensions and enhanced functionalities.