Discovering Synthesis Routes to Hexagonally Ordered Mesoporous Niobium Nitrides Using Poloxamer/Pluronics Block Copolymers

Discovering Synthesis Routes to Hexagonally Ordered Mesoporous Niobium Nitrides Using Poloxamer/Pluronics Block Copolymer

Self-Assembled Gyroidal Mesoporous Polymer-Derived High Temperature Ceramic Monoliths

Polymer-derived ceramics (PDCs) have enabled the development of nonoxide ceramic coatings and fibers with exceptional thermo-mechanical stability. Here, we report the self-assembly based synthesis of gyroidal (space group Q²³⁰, <i>Ia</i>3̅<i>d</i>) mesoporous silicon oxynitride ceramic monoliths by pyrolysis of blends of commercially available preceramic polysilazane with a structure-directing triblock terpolymer up to temperatures of 1000 °C. Monoliths had pore diameters of 9.4 ± 1.1 nm and surface area of 160 m²/g. The three-dimensionally (3D) ordered periodic pore structure of the as-made hybrids acts to relieve stresses by allowing the escape of gases formed during ceramization. This process in turn enables the retention of smooth monoliths during ceramization under ammonia, a process that both adds nitrogen to the material and removes carbon pyrolysis products. The monoliths are appealing for high-temperature applications such as catalyst supports and microelectromechanical system (MEMS) devices including gas and pressure sensors, as well as strong, stiff, and creep-resistant scaffolds for ordered interpenetrating phase composites