Potentiometric properties of ion-selective electrode membranes based on segmented polyether urethane matrices

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Polyurethane (PU) matrices are explored for ion-selective electrode (ISE) membranes.
• The role of soft segments, plasticizers (DOA), and lipophilic additives (KTpClPB) in PU membranes is investigated.
• Understanding these components is crucial for optimizing potentiometric sensor performance.

Purpose of the Study:

• To examine the potentiometric responses of valinomycin-doped PU membranes.
• To investigate the influence of soft segment content on the required amounts of plasticizer and lipophilic additives.
• To determine optimal PU compositions for fabricating efficient ISE membranes.

Main Methods:

• Fabrication of PU-based membranes with varying soft segment (poly(tetramethylene ether glycol)) contents.
• Incorporation of valinomycin, plasticizer (DOA), and/or lipophilic additive (KTpClPB).
• Potentiometric measurements to evaluate the response to potassium ions, focusing on near-Nernstian behavior.

Main Results:

• Increasing soft segment content in PU matrices significantly reduces the need for DOA and/or KTpClPB for near-Nernstian potassium response.
• Soft segments act as internal plasticizers, imparting a rubbery structure (Tg < -58 °C).
• Plasticizer-free PU membranes are feasible with high soft segment content (≥ 60 wt %) due to interactions between anionic sites and urethane chains.

Conclusions:

• PU matrices with 60–80 wt % soft segments are ideal for creating ISE membranes with minimal or no plasticizer.
• This research facilitates the development of more stable and durable ion-selective electrodes.
• The findings offer a pathway to reduce reliance on traditional plasticizers in membrane fabrication.