Promising Functional Materials Based on Ladder Polysiloxanes

Abstract Preparation of real ladder polysiloxanes (LPSs), including both oxygen‐bridged ladder polysilsesquioxanes (LPSQs) and organo‐bridged ladder polysiloxanes (OLPSs), had been a great challenge to polymer chemists from 1960 until the successful synthesis of LPSs via the supramolecular architecture‐directed stepwise coupling polymerization (SCP) in the early 1980s. This opened up a new field of LPS‐based advanced materials. As key building blocks, LPSs are used to construct a variety of polysiloxanes with special steric configurations and functions, such as mesomorphic LPSs, tubular polysiloxanes (TPs), and pseudo‐sieve‐plate polysiloxanes (pseudo‐SPSs). With excellent temperature and radiation resistance, good solubility, and fine optical and mechanical properties, all these polysiloxanes demonstrate very promising prospects in the advanced materials realm. Here, the synthesis of well‐ordered LPSs is presented and features of fishbone‐like and rowboat‐like liquid crystalline polysiloxanes are discussed. Special emphasis is given to typical applications of LPSs, TPSs, and pseudo‐SPSs in the areas of liquid crystal displays, microelectronics packaging, and nonlinear optical materials.