Voltammetric determination of diffusion coefficients in polymer membranes

Area of Science:

• Electrochemistry
• Materials Science
• Sensor Technology

Background:

• Diffusion-controlled transport in polymer membranes is critical for chemical and biosensor response.
• Accurate measurement of diffusion coefficients is essential for optimizing sensor design and performance.

Purpose of the Study:

• To develop and validate a simple voltammetric method for determining diffusion coefficients of redox molecules in resistive polymer membranes.
• To assess the accuracy of the proposed method using established electrochemical simulation techniques.

Main Methods:

• Utilized a planar electrochemical cell (PEC) with a 5 μm radius carbon fiber working electrode.
• Assessed diffusion coefficients by analyzing the scan rate dependence of peak currents in linear sweep and cyclic voltammograms.
• Employed Nicholson and Shain simulations to validate the quantitative relationship between peak current and scan rate.

Main Results:

• Successfully measured diffusion coefficients of ferrocene derivatives in various media, including aqueous solutions, organic solvents, plasticizers, and plasticized PVC membranes.
• Demonstrated good agreement between experimentally determined diffusion coefficients and theoretical models.
• Validated the accuracy of the voltammetric method through simulations.

Conclusions:

• The developed voltammetric method provides a simple and accurate means to determine diffusion coefficients in resistive polymer membranes.
• This technique is applicable across a range of solvents and membrane compositions, offering versatility for sensor development.
• The findings contribute to a better understanding of transport phenomena in polymer membranes, aiding in the design of advanced chemical and biosensors.