Understanding Thermodynamics and Kinetics of PEDOT:PSS Using ATR-FTIR and Density Functional Theory

Area of Science:

• Materials Science
• Polymer Chemistry
• Conducting Polymers

Background:

• Poly(3,4-ethylenedioxythiophene) polystyrenesulfonate (PEDOT:PSS) is a widely used conducting polymer with good electrical properties but suffers from poor dispersibility in solution.
• Developing insoluble and porous forms of PEDOT:PSS is crucial for advanced applications requiring stable material structures.

Purpose of the Study:

• To demonstrate the cross-linking of PEDOT:PSS with divinyl sulfone (DVS) to create insoluble and porous hydrogels.
• To elucidate the reaction mechanism and kinetics governing the PEDOT:PSS-DVS cross-linking process.
• To investigate methods for inducing controlled porosity in the resulting hydrogels.

Main Methods:

• Real-time attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) for reaction monitoring.
• Density functional theory (DFT) calculations to support the proposed reaction mechanism.
• Cryogelation, phase separation, and phase inversion techniques to introduce porosity.
• Kinetic analysis to determine rate expressions, pre-exponential factors, and activation energy.

Main Results:

• A second-order reaction mechanism between DVS and PSS was proposed and supported by experimental and computational data.
• A temperature-dependent rate expression was determined, with a pre-exponential factor of 1.458 1/s and an activation energy of 2.429 kcal/mol.
• Porous PEDOT:PSS-DVS hydrogels with pore sizes ranging from 12 to 121 μm were successfully fabricated using various methods.
• The resulting porous hydrogels demonstrated insolubility, maintaining their structural integrity in solution.

Conclusions:

• The study successfully developed insoluble and porous PEDOT:PSS-DVS hydrogels through a well-defined cross-linking reaction.
• The reaction mechanism and kinetics were thoroughly investigated, providing fundamental insights into the modification of PEDOT:PSS.
• The developed porous, insoluble hydrogels offer promising characteristics for applications where material stability and controlled architecture are essential.