Supramolecular Chemistry in Microflow Fields: Toward a New Material World of Precise Kinetic Control

Abstract

Constructing new and versatile self-assembling systems in supramolecular chemistry is much like the development of new reactions or new catalysts in synthetic organic chemistry. As one such new technology, conventional supramolecular assembly systems have been combined with microflow techniques to control intermolecular or interpolymer interactions through precise regulation of a flowing self-assembly field. The potential of the microflow system has been explored by using various simple model compounds. Uniform solvent diffusion in the microflow leads to rapid activation of molecules in a nonequilibrium state and, thereby, enhanced interactions. All of these self-assembly processes begin from a temporally activated state and proceed in a uniform chemical environment, forming a synchronized cluster and resulting in effective conversion to supramolecules, with precise tuning of molecular (or polymer) interactions. This approach allows the synthesis of a variety of discrete microstructures (e.g., fibers, sheets) and unique supramolecules (e.g., hierarchical assemblies, capped fibers, polymer networks, supramolecules with time-delayed action) that have previously been inaccessible.

Non-equilibrium supramolecular polymerization

“…, the concentration gradients and solvent composition in space, and the interfaces at which nucleation occurs. Numata and co-workers 39 used microfluidic conditions for the kinetically controlled preparation of porphyrin assemblies from nano to micro scale. For example, they found that the polymerization of H 2 TPPS to form J-aggregates, as triggered by its protonation, is strongly enhanced under microfluidic mixing, and occurs at final conditions at which it is not observed in a flask ( Fig.…”

Wet spinning and radial self-assembly of a carbohydrate low molecular weight gelator into well organized hydrogel filaments

“…Applying well-controlled external triggers should bring interesting self-assembling effects and may result in new kinds of self-assembled materials with more controlled properties. Some studies described the use of shear stress, 26,[29][30][31][32][33] controlled reagent exchanges in microfluidic devices, [34][35][36][37][38] electrical 39 or magnetic fields, 40,41 surface effects [42][43][44] or ice growth 45 to control self-assembly. While microfluidics is often used to control the self-assembly of micelles, particles, liquid crystals and some polymers, 46,47 it is scarcely the case for molecular gels.…”

Molecular Synchronization Enhances Molecular Interactions: An Explanatory Note of Pressure Effects

“…In contrast to this general behavior in solution, we have found that the efficiency of J-aggregate formation is correlated to the time required for protonation of H 4 TPPS [1]. Very rapid proton diffusion in a microflow channel [9][10][11][12][13][14] results in increasing temporal H 4 TPPS concentrations, even at a constant value of pH [15,16].…”