Spontaneous Mesoporosity-Driven Sequestration of Ionic Liquids from Silicone-Based Reference Electrode Membranes

Area of Science:

• Electrochemistry
• Materials Science
• Analytical Chemistry

Background:

• Reference electrodes are crucial for electrochemical measurements.
• Polydimethylsiloxane (PDMS) membranes with ionic liquids are used in reference electrodes.
• Colloid-imprinted mesoporous carbon (CIM) is a potential solid contact material.

Purpose of the Study:

• To investigate the functionality of PDMS reference membranes with CIM solid contacts.
• To identify the cause of reference electrode failure.
• To propose solutions for improving reference electrode performance.

Main Methods:

• Fabrication of reference electrodes using PDMS membranes and CIM solid contacts.
• Analysis of ionic liquid distribution and membrane properties.
• Observation of material interactions during electrode fabrication and operation.

Main Results:

• Nanopore-driven sequestration of ionic liquids from PDMS membranes into CIM was observed.
• This sequestration leads to increased membrane resistance and device dysfunction.
• Similar depletion of ionophores from silicone membranes was noted.

Conclusions:

• The interaction between porous solid contacts and polymeric membranes can lead to depletion of active components.
• Presaturating CIM with ionic liquid or increasing ionic liquid content in the membrane prevents dysfunction.
• This phenomenon may be widespread in similar electrochemical devices.