Density functional theory assessment of molecular interactions and electronic properties in lithium Bis(trifluoromethanesulfonyl)imide with inorganic and organic polymer derived eutectogel

The present work focuses on the structural stability of deep eutectic solvents (DES) with polymer matrix, known as eutectogel (ETG), using a computational approach by employing density functional theory (DFT). All quantum chemical calculations are being done using the Quantum ESPRESSO package that works on plane waves as a basis set. Two types of eutectogel, i.e., ETG1 and ETG2, are designed based on an inorganic silica gel (SiO2-gel) and organic poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) polymer matrix. This incorporates a deep eutectic solvent (DES) consisting of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as the hydrogen bond acceptor (HBA) and n-methylacetamide (NMAc) as the hydrogen bond donor (HBD) in a ratio of 1:4. For identifying structural stability in these eutectogels, intermolecular attraction, binding energy, and interaction energy have been taken into account. Other electronic properties like band gap, electronegativity, chemical potential, and electrophilicity index are obtained using HOMO-LUMO information. Both ETGs show structural integrity, but higher interaction is found for ETG1 compared to ETG2. The highest HOMO-LUMO energy gap is obtained for ETG1 (4.271 eV) and the lowest for ETG2 (3.184 eV), respectively. This indicates that ETG1 has a higher degree of stability and low polarization than ETG2.