As functionalized 2D materials are incorporated into hybrid materials, ensuring large-area structural control in noncovalently adsorbed films becomes increasingly important. Noncovalent functionalization avoids disrupting electronic structure in 2D materials; however, relatively weak molecular interactions in such monolayers typically reduce stability toward solution processing and other common material handling conditions. Here, we find that controlling substrate temperature during Langmuir–Schaefer conversion of a standing phase monolayer of diynoic amphiphiles on water to a horizontally oriented monolayer on a 2D substrate routinely produces multimicrometer domains, at least an order of magnitude larger than those typically achieved through drop-casting. Following polymerization, these highly ordered monolayers retain their structures during vigorous washing with solvents including water, ethanol, tetrahydrofuran, and toluene. These findings point to a convenient and broadly applicable strategy for noncovalent functionalization of 2D materials in applications that require large-area structural control, for instance, to minimize desorption at defects during subsequent solution processing.Keywords: 2D materials; Langmuir−Schaefer transfer; noncovalent functionalization; polymerizable amphiphile; self-assembled monolayer; self-assembly;

The use of dimensionally ordered ligands on layered materials to direct local electronic structure and interactions with the environment promises to streamline integration into nanostructured electronic, optoelectronic, sensing, and nanofluidic interfaces. Substantial progress has been made in using ligands to control substrate electronic structure. Conversely, using the exposed face of the ligand layer to structure wetting and binding interactions, particularly with scalable solution- or spray-processed materials, remains a significant challenge. However, nature routinely utilizes wetting control at scales from nanometer to micrometer to build interfaces of striking geometric precision and functional complexity, suggesting the possibility of leveraging similar control in synthetic materials. Here, we assemble striped “sitting” phases of polymerizable phospholipids on highly oriented pyrolytic graphite, producing a surface consisting of 1 nm wide hydrophilic stripes alternating with 5 nm wide hydrophobic stripes. Protruding, strongly wetting headgroup chemistries in these monolayers enable formation of rodlike wetted patterns with widths as little as ∼6 nm and lengths up to 100 nm from high-surface-tension liquids (aqueous solutions of glycerol) commonly utilized to assess interfacial wetting properties at larger length scales. In contrast, commonly used lying-down phases of diynoic acids with in-plane headgroups do not promote droplet sticking or directional spreading. These results point to a broadly applicable strategy for achieving high-resolution solution-based patterning on layered materials, utilizing nanometer-wide patterns of protruding, charged functional groups in a noncovalent monolayer to define pattern edges.Keywords: anisotropic wetting; directional wetting; diynoic phospholipid; layered materials; nanoscale wetting; noncovalent functionalization; self-assembled monolayer; self-assembly;

Integrating functionalized 2D materials into multilayer device architectures increasingly requires understanding the behavior of noncovalently adsorbed ligands during solution processing. Here, we demonstrate that the headgroup dynamics of polymerized monolayers of functional alkanes can be controlled to modify surface wetting and environmental interactions. We find that headgroup dynamics are sensitive to the position of the polymerizable diyne group; thus, the polymerization process, typically used to stabilize the noncovalent monolayer, can also be used to selectively destabilize chain–chain interactions near the headgroups, making the headgroups more solvent-accessible and increasing surface hydrophilicity. Conversely, interactions with divalent ions can be used to tether headgroups in-plane, decreasing surface hydrophilicity. Together, these results suggest a strategy for the rational design of 2D chemical interfaces in which the polymerization step reconfigures the monolayer to promote the desired environmental interactions.

Precisely tailoring surface chemistry of layered materials is a growing need for fields ranging from electronics to biology. For many applications, the need for noncovalently adsorbed ligands to simultaneously control interactions with a nonpolar substrate and a polar solvent is a particular challenge. However, biology routinely addresses a similar challenge in the context of the lipid bilayer. While conventional standing phases of phospholipids (such as those found in a bilayer) would not provide spatially ordered interactions with the substrate, here we demonstrate formation of a sitting phase of polymerizable phospholipids, in which the two alkyl chains extend along the surface and the two ionizable functionalities (a phosphate and an amine) sit adjacent to the substrate and project into the solvent, respectively. Interfacial ordering and polymerization are assessed by high-resolution scanning probe measurements. Water contact angle titrations demonstrate interfacial pKa shifts for the lipid phosphate but not for the amine, supporting localization of the phosphate near the nonpolar graphite surface.

Scanning probe microscopy methods have enabled characterization of surface topography and electronic structure down to the nanometer (and in some cases atomic) scale. As such techniques have become more widely used, a growing community of researchers has sought to broaden the imaging capabilities of scanning probe microscopy to provide not just topographical, but also detailed chemical information about interfaces at these length scales. Here, we provide a tutorial review describing developments in the field of multimodal scanning probe microscopy, highlighting both foundational work and recent advances that have facilitated applications ranging from studies of biological structure and function to streamlined development of materials for renewable energy.

Scanning probe microscopy methods have enabled characterization of surface topography and electronic structure down to the nanometer (and in some cases atomic) scale. As such techniques have become more widely used, a growing community of researchers has sought to broaden the imaging capabilities of scanning probe microscopy to provide not just topographical, but also detailed chemical information about interfaces at these length scales. Here, we provide a tutorial review describing developments in the field of multimodal scanning probe microscopy, highlighting both foundational work and recent advances that have facilitated applications ranging from studies of biological structure and function to streamlined development of materials for renewable energy.