Templated Sub‐100‐nm‐Thick Double‐Gyroid Structure from Si‐Containing Block Copolymer Thin Films

The directed self‐assembly of diblock copolymer chains (poly(1,1‐dimethyl silacyclobutane)‐block‐polystyrene, PDMSB‐b‐PS) into a thin film double gyroid structure is described. A decrease of the kinetics of a typical double‐wave pattern formation is reported within the 3D‐nanostructure when the film thickness on mesas is lower than the gyroid unit cell. However, optimization of the solvent‐vapor annealing process results in very large grains (over 10 µm²) with specific orientation (i.e., parallel to the air substrate) and direction (i.e., along the groove direction) of the characteristic (211) plane, demonstrated by templating sub‐100‐nm‐thick PDMSB‐b‐PS films.     

One‐Dimensional Nano‐Interconnection Formation

Interconnection of one‐dimensional nanomaterials such as nanowires and carbon nanotubes with other parts or components is crucial for nanodevices to realize electrical contacts and mechanical fixings. Interconnection has been being gradually paid great attention since it is as significant as nanomaterials properties, and determines nanodevices performance in some cases. This paper provides an overview of recent progress on techniques that are commonly used for one‐dimensional interconnection formation. In this review, these techniques could be categorized into two different types: two‐step and one‐step methods according to their established process. The two‐step method is constituted by assembly and pinning processes, while the one‐step method is a direct formation process of nano‐interconnections. In both methods, the electrodeposition approach is illustrated in detail, and its potential mechanism is emphasized.     

Three‐Dimensional Fabrication at Small Size Scales

Despite the fact that we live in a 3D world and macroscale engineering is 3D, conventional submillimeter‐scale engineering is inherently 2D. New fabrication and patterning strategies are needed to enable truly 3D‐engineered structures at small size scales. Here, strategies that have been developed over the past two decades that seek to enable such millimeter to nanoscale 3D fabrication and patterning are reviewed. A focus is the strategy of self‐assembly, specifically in a biologically inspired, more deterministic form, known as self‐folding. Self‐folding methods can leverage the strengths of lithography to enable the construction of precisely patterned 3D structures and “smart” components. This self‐assembly approach is compared with other 3D fabrication paradigms, and its advantages and disadvantages are discussed.

     

Preparation of Macroscopic Block‐Copolymer‐Based Gyroidal Mesoscale Single Crystals by Solvent Evaporation

Properties arising from ordered periodic mesostructures are often obscured by small, randomly oriented domains and grain boundaries. Bulk macroscopic single crystals with mesoscale periodicity are needed to establish fundamental structure–property correlations for materials ordered at this length scale (10–100 nm). A solvent‐evaporation‐induced crystallization method providing access to large (millimeter to centimeter) single‐crystal mesostructures, specifically bicontinuous gyroids, in thick films (>100 µm) derived from block copolymers is reported. After in‐depth crystallographic characterization of single‐crystal block copolymer–preceramic nanocomposite films, the structures are converted into mesoporous ceramic monoliths, with retention of mesoscale crystallinity. When fractured, these monoliths display single‐crystal‐like cleavage along mesoscale facets. The method can prepare macroscopic bulk single crystals with other block copolymer systems, suggesting that the method is broadly applicable to block copolymer materials assembled by solvent evaporation. It is expected that such bulk single crystals will enable fundamental understanding and control of emergent mesostructure‐based properties in block‐copolymer‐directed metal, semiconductor, and superconductor materials.     

Construction of 3D Polymer Brushes by Dip‐Pen Nanodisplacement Lithography: Understanding the Molecular Displacement for Ultrafine and High‐Speed Patterning

Dip‐pen nanodisplacement lithography (DNL) is a versatile scanning probe‐based technique that can be employed for fabricating ultrafine 3D polymer brushes under ambient conditions. Many fundamental studies and applications require the large‐area fabrication of 3D structures. However, the fabrication throughput and uniformity are still far from satisfactory. In this work, the molecular displacement mechanism of DNL is elucidated by systematically investigating the synergistic effect of z extension and contact time. The in‐depth understanding of molecular displacement results in the successful achievement of ultrafine control of 3D structures and high‐speed patterning at the same time. Remarkably, one can prepare arbitrary 3D polymer brushes on a large area (1.3 mm × 1.3 mm), with <5% vertical and lateral size variations, and a patterning speed as much as 200‐fold faster than the current state‐of‐the‐art.     

Spatiotemporally Controllable Peptide‐Based Nanoassembly in Single Living Cells for a Biological Self‐Portrait

Simultaneous precise localization and activity evaluation of a biomolecule in a single living cell is through an enzyme‐specific signal‐amplification process, which involves the localized, site‐specific self‐assembly, and activation of a presignaling molecule. The inactive presignaling tetraphenylethylene (TPE)‐peptide derivative, TPE‐YpYY, is nondetectable and highly biocompatible and these small molecules rapidly diffuse into living cells. Upon safely arriving at an active site, and accessing the catalytic pocket of an enzyme, TPE‐YpYY immediately and quantitatively accumulates in situ in response to enzymatic activity, forms an enzyme anchor TPE‐YYY nanoassembly, displays aggregation‐induced emission behavior, and finally lights up the active enzyme, indicating its activity, and allowing its status in living cells to be tracked. This simple and direct self‐portrait method can be used to monitor dynamic self‐assembly processes in individual living cells and may provide new insights that reveal undiscovered biological processes and that aid in developing biomedical hybrid devices. In the future, this strategy of molecular design can be further expanded to the noninvasive investigation of other bioactive molecules, thus facilitating quantitative imaging.     

Sacrificial‐Post Templating Method for Block Copolymer Self‐Assembly

A sacrificial‐post templating method is presented for directing block copolymer self‐assembly to form nanostructures consisting of monolayers and bilayers of microdomains. In this approach, the topographical post template is removed after self‐assembly and therefore is not incorporated into the final microdomain pattern. Arrays of nanoscale holes of different shapes and symmetries, including mesh structures and perforated lamellae with a bimodal pore size distribution, are produced. The ratio of the pore sizes in the bimodal distributions can be varied via the template pitch, and agrees with predictions of self consistent field theory.