Quantum Chemical Calculation of Metal-backboned Polymer

Metal-backboned polymers (MBPs) are a new class of materials with metal atoms for backbones, which offer excellent electronic properties for promising applications in a variety of fields such as optoelectronics, sensing, and energy storage. However, it remains challenges to synthesize MBPs with high molecular weights for practical applications. Here, the structures of nickel-backboned polymers (NiBPs) with increasing molecular weights were optimized by density functional theory (DFT) method, based on which their stabilities were further studied. It was found that the energies of NiBPs gradually decreased with the increasing molecular weight, indicating that NiBPs with higher molecular weights showed stable molecular configurations. However, with the further increase of molecular weights, it was difficult for NiBPs to converge by DFT method. To this end, these structures were further studied by Hartree-Fock method. Similar results had been concluded as DFT calculation did, and it also proved that an NiBP with molecular weight exceeding 1x104 was also stable. In addition, the unique metal-metal interaction of the electron delocalization on the whole metal backbone is conducive to the efficient transmission of charge. As polymers with repeating metal atom units, MBPs are expected to have combined properties of metal and polymer materials, and may demonstrate high thermal weight loss temperatures and entropy elasticities. This work provides a theoretical basis for the synthesis of MBP materials.