Liquid crystalline polymeric wires for selective proton transport, part 2: Ion transport in solid-state

- Ion-transport studies for hybrid biomimetic membranes are described.
- Improved and cation permselective transport in oriented polymeric columns is found.
- Remarkable cation preferential selectivity is shown by linear sweep voltammetry.

A study of ion transport in a new generation of hybrid biomimetic membranes, which are based on the formation of polymeric ionic wires via exo-recognition and subsequent orientation by thermal treatment, is presented. The specific conductivity of the hybrid membranes, obtained by electrochemical impedance spectroscopy, is not strongly affected by relative humidity and temperature; the values are found around 10−5 S/cm for all studied materials. However, in the case of ion transport observed by linear sweep voltammetry, the hybrid materials containing homeotropically oriented columns exhibited lower resistance than unoriented samples. The preferential selectivity, expressed as conductance ratio compared to proton cation, show remarkably better results for biomimetic membranes when compared to Nafion® 117. Low values of methanol crossover are also found. Taking into account these findings, these materials hold great promise for practical application requiring selective ion transport.

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