Enhancement of anhydrous proton transport by supramolecular nanochannels in comb polymers

Abstract

Transporting protons is essential in several biological processes as well as in renewable energy devices, such as fuel cells. Although biological systems exhibit precise supramolecular organization of chemical functionalities on the nanoscale to effect highly efficient proton conduction, to achieve similar organization in artificial systems remains a daunting challenge. Here, we are concerned with transporting protons on a micron scale under anhydrous conditions, that is proton transfer unassisted by any solvent, especially water. We report that proton-conducting systems derived from facially amphiphilic polymers that exhibit organized supramolecular assemblies show a dramatic enhancement in anhydrous conductivity relative to analogous materials that lack the capacity for self-organization. We describe the design, synthesis and characterization of these macromolecules, and suggest that nanoscale organization of proton-conducting functionalities is a key consideration in obtaining efficient anhydrous proton transport.

Facile Anhydrous Proton Transport on Hydroxyl Functionalized Graphane

“…The mechanism of PT in aqueous systems has been extensively studied and is well understood. In contrast, the PT mechanisms under anhydrous conditions appear to depend on the material and are a matter of debate [5][6][7][8]. This work provides atomic-level insight into how PT takes place on OH-functionalized graphane and why the barriers to PT on this material are so low.…”

Liquid crystalline polymeric wires for selective proton transport, part 1: Wires preparation

“…This example suggested that supramolecular organization is crucial in obtaining efficient proton transport. [7] To achieve a highly organized structure of aromatic cores of discotic columnar liquid crystals, support with nanoconfinements was used.…”

Enhancing proton conduction via doping of supramolecular liquid crystals (4-alkoxybenzoic acids) with imidazole

“…We succeeded in obtaining proton conductivity of 4.7 × 10 −3 S cm −1 at 200 • C in the layered side-chain liquid crystal polymers bearing sulfonic acids [11]. Styrenic comb polymers self-assembling into supramolecular structures with cylindrical imidazole-rich domains showed proton conductivity of 10 −3 S cm −1 at 200 • C [12]. Proton conduction in these supramolecular self-assemblies occurred by successive proton transfers along the ordered hydrogen bond networks.…”