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

This work demonstrates poly(3,4-ethylenedioxythiophene) polystyrenesulfonate (PEDOT:PSS) and divinyl sulfone (DVS) cross-linking to form insoluble and porous PEDOT:PSS-DVS hydrogels. We propose a reaction mechanism and demonstrate the kinetics of a PEDOT:PSS modification that prevents PEDOT:PSS dispersibility. PSS and DVS undergo a second-order reaction between the DVS secondary carbocations and PSS oxygen anion to form a PSS-DVS network. The kinetics, from real-time attenuated total reflectance-Fourier transform infrared spectroscopy and density functional theory, reveal a temperature-dependent rate expression with a 1.458 1/s pre-exponential factor and a 2.429 kcal/mol activation energy. Cryogelation, phase separation, and phase inversion methods induce porosity in the PEDOT:PSS-DVS hydrogels with pore sizes ranging from 12 to 121 μm. Most importantly, the porous PEDOT:PSS-DVS hydrogels do not redisperse in solution. The results provide evidence for the reaction mechanism and kinetics of porous nondispersible PEDOT:PSS-DVS hydrogels.