ATOMISTIC SIMULATION OF HYDRONIUM ION INTERACTIONS WITH POLYSULFOBETAINE: INSIGHTS FOR PROTON EXCHANGE MEMBRANE ENVIRONMENTS

The ongoing shortcomings of existing proton exchange membranes (PEMs), which frequently have poor ionic conductivity and insufficient chemical stability under operating circumstances, seriously impede the development of fuel cell technology. Research has concentrated on creating innovative polymeric materials with improved proton transport and strong molecular frameworks in order to address these issues. The use of polysulfobetaine (PSB), a zwitterionic polymer, is suggested in this work as a viable option for next-generation PEMs because of its capacity to form hydrophilic proton-conducting channels while preserving structural integrity. We used Density Functional Theory (DFT) simulations to study the fundamental interactions between a hydronium ion (H₃O⁺) and a polysulfobetaine monomer in an explicit water solvent environment at the atomistic scale. According to the study of the DFT-optimized structure, the hydronium ion and the negatively charged sulfonate group of the betaine unit exhibit strong electrostatic interaction. Significant charge transfer and polarization upon complexation are confirmed by Mulliken charge distribution and bond length studies. The advantageous binding locations for the proton carrier are graphically represented by molecular electrostatic potential (MEP) maps. Additionally, analysis of the HOMO-LUMO orbitals and their energy gap provides insight into the system’s electronic structure stability and reactivity. These findings provide fundamental quantum-chemical evidence that the molecular structure of polysulfobetaine can efficiently coordinate and stabilize hydronium ions, an essential step for promoting proton-hopping (Grotthuss) mechanisms and enhancing membrane performance in general.

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