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Jong-Hyun Ahn

Publications and source records attributed to Jong-Hyun Ahn.

5 recordsLinked to original sources

Heterogeneous three-dimensional electronics by use of printed semiconductor nanomaterials.

We developed a simple approach to combine broad classes of dissimilar materials into heterogeneously integrated electronic systems with two- or three-dimensional layouts. The process begins with the synthesis of different semiconductor nanomaterials, such as single-walled carbon nanotubes and single-crystal micro- and nanoscale wires and ribbons of gallium nitride, silicon, and gallium arsenide on separate substrates. Repeated application of an additive, transfer printing process that uses soft stamps with these substrates as donors, followed by device and interconnect formation, yields high-performance heterogeneously integrated electronics that incorporate any combination of semiconductor nanomaterials on rigid or flexible device substrates. This versatile methodology can produce a wide range of unusual electronic systems that would be impossible to achieve with other techniques.

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Supramolecular barrels from amphiphilic rigid-flexible macrocycles.

Precise control of supramolecular objects requires the rational design of molecular components, because the information determining their specific assembly should be encoded in their molecular architecture. In this context, diverse self-assembling molecules including liquid crystals, dendrimers, block copolymers, hydrogen-bonded complexes and rigid macrocycles are being created as a means of manipulating supramolecular structure. Incorporation of a stiff rod-like building block into an amphiphilic molecular architecture leads to another class of self-assembling molecules. Aggregation of rod building blocks can generate various nanoscale objects including bundles, ribbons, tubules and vesicles, depending on the molecular structure and/or the presence of a selective solvent. We present here an unusual example of supramolecular barrels in the solid and in aqueous solution, based on the self-assembly of amphiphilic rigid-flexible macrocycles driven by non-covalent interactions. Preliminary experiments show that these amphiphilic macrocycles are membrane-active. The amphiphilic macrocycles might thus lead to an excellent model system for exploring biological processes in supramolecular materials.

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Shape-persistent macromolecular disks from reactive supramolecular rod bundles.

We have synthesized a coil-rod-coil molecule based on a reactive rod block that self-organizes into a 3-D hexagonal close-packed (hcp) bundle structure in the melt state. Photo-cross-linking within an aromatic bundle yielded macromolecular disklike objects (molecular weight of 330 kDa) with a narrow size distribution that was essentially the same as that of the supramolecular bundles. In addition, cross-linking proceeded with the retention of the 3-D hcp symmetry of the supramolecular bundles. The 3-D symmetry of the macromolecular objects was observed to recover after their isolation from the solutions and transform into an isotropic liquid in the bulk state in a reversible way, suggesting that the macromolecular objects are shape-persistent in solutions as well as an isotropic liquid phase of the bulk.

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