High Proton-Conductivity in Covalently Linked Polyoxometalate-Organoboronic Acid-Polymers

Angew Chem Int Ed Engl. 2021 Jul 26;60(31):16953-16957. doi: 10.1002/anie.202104886. Epub 2021 Jun 28.

Abstract

The controlled bottom-up design of polymers with metal oxide backbones is a grand challenge in materials design, as it could give unique control over the resulting chemical properties. Herein, we report a 1D-organo-functionalized polyoxometalate polymer featuring a purely inorganic backbone. The polymer is self-assembled from two types of monomers, inorganic Wells-Dawson-type polyoxometalates, and aromatic organo-boronates. Their covalent linkage results in 1D polymer strands, which combine an inorganic oxide backbone (based on B-O and Nb-O linkages) with functional organic side-chains. The polymer shows high bulk proton conductivity of up to 1.59×10-1 S cm-1 at 90 °C and 98 % relative humidity. This synthetic approach could lead to a new class of organic-inorganic polymers where function can be designed by controlled tuning of the monomer units.

Keywords: boronic acid; organo-functionalization; polyoxometalate; self-assembly; supramolecular chemistry.