Showing papers by "Franklin Kim published in 2012"

Crystal morphology-directed framework orientation in porous coordination polymer films and freestanding membranes via Langmuir–Blodgettry

Abstract: Porous coordination polymers (PCPs), with their ordered nanoporous systems and large surface areas, are very attractive for numerous applications that involve controlled molecular transport properties. To fully exploit their potential, a straightforward processing method to deposit the PCP crystals on various substrates and to create freestanding membranes with a controlled pore orientation is highly desirable. Here, we report a strategy to self-assemble PCP crystals into two-dimensional monolayers using Langmuir–Blodgettry. This approach allows the deposition on various substrates over several square centimeters, uniformly and with controllable density of the crystals. In addition we show that by controlling the morphology of the crystalline building blocks we can program their orientation on the substrates. Using a copper grid as the substrate, these assemblies can also be fabricated as freestanding sheets. This approach represents a very simple and scalable processing method to translate the orientation of the channel network from the individual crystal to the macroscopic scale, and can help to incorporate this interesting class of materials within advanced hierarchical systems.

Self-Assembly of Two-Dimensional Nanosheets Induced by Interfacial Polyionic Complexation

Abstract: Significant progress has been made during the past decade in preparing nanosheets from a wide range of materials, which are actively pursued for various applications such as energy storage, catalysis, sensing, and membranes. One of the next critical challenges is developing a robust and versatile assembly method which allows construction of the nanosheets into functional structures tailored for each specific purpose. An interesting characteristic of nanosheets is that they often behave as charged macromolecules and thus can readily interact with an oppositely charged polyelectrolyte to form a stable complex. In this report, we demonstrate how such a complexation process could be utilized for directing the self-assembly of nanosheets. By confining the nanosheet–polyelectrolyte complexation at air–liquid or liquid–liquid interfaces, the nanosheets are successfully assembled into various mesoscale architectures including fibers, capsules, and films. Furthermore, incorporation of additional components such as...