Ultra-high temperature ceramics (UHTCs) are generally referred to the carbides, nitrides, and borides of the transition metals, with the Group IVB compounds (Zr & Hf) and TaC as the main focus. The UHTCs are endowed with ultra-high melting points, excellent mechanical properties, and ablation resistance at elevated temperatures. These unique combinations of properties make them promising materials for extremely environmental structural applications in rocket and hypersonic vehicles, particularly nozzles, leading edges, and engine components, etc. In addition to bulk UHTCs, UHTC coatings and fiber reinforced UHTC composites are extensively developed and applied to avoid the intrinsic brittleness and poor thermal shock resistance of bulk ceramics. Recently, highentropy UHTCs are developed rapidly and attract a lot of attention as an emerging direction for ultra-high temperature materials. This review presents the state of the art of processing approaches, microstructure design and properties of UHTCs from bulk materials to composites and coatings, as well as the future directions.

Unorthodox luminescent polymers without large π-conjugated structures, as promising soft luminescent materials, have recently received considerable attention owing to the availability of versatile preparation methods and their good processability. These polymers generally possess electron-rich moieties, with a diversity of intermolecular and intramolecular interactions through delocalized electrons. Therefore, polymerization itself can be an effective way to realize fluorescence emission. Here, polymerization-induced emission (PIE) is conceptualized as the process of transforming non-luminescent small molecules (i.e., monomers) into luminescent polymers. Correspondingly, PIE luminogens (PIEgens) with luminescent clusters, which are proposed as group aggregates with the minimum critical size for emission, require further investigation in order to understand the structure–emission relationships and related mechanisms. Promisingly, advanced polymerization methods offer unlimited opportunities to develop new soft luminescent polymers owing to the multi-level structures of polymers.