Synthesis and properties of metallo-supramolecular poly(p-xylylene)s

The self-assembly polymerization of ditopic macromolecules via metal-ligand binding offers a facile route to the preparation of metallo-supramolecular polymers. We herein report the utilization of this approach for the synthesis of arylene alkylene metallopolymers, which combine ease of processing with good high-temperature stability. The materials are based on a poly(2,5-dioctyloxy-p- xylylene) macromonomer that was prepared by in-situ end-capping of a low-molecular-weight poly(2,5-dioctyloxy-p-phenylene ethynylene) core with 2,6-bis(1′-methylbenzimidazolyl)-4-ethynylpyridine (Mebip) ligands and subsequent reduction under Hahn diimide conditions. The supramolecular polymerization of this macromonomer with equimolar amounts of Zn ²⁺ or Fe ²⁺ and a small amount of La ³⁺, which can bind three Mebip ligands and causes cross-linking and/or branching, resulted in materials which offer excellent mechanical properties. The thermomechanical properties of the new polymers were investigated by a variety of techniques, including modulated differential scanning calorimetry, dynamic mechanical thermoanalysis, and thermogravimetric analysis.