Abstract
Survey of the present state of the chemistry of these polymers and examination of their resistance to various types of degradation show that a ladder structure does not guarantee great stability, although a high degree of structural perfection and highly stable heterocycles confer significantly improved heat resistance, thermal stability, non-flammability, radiation resistance, etc. relative to traditional heteroarylenes. The principal methods for synthesising ladder polyheteroarylenes of high degrees of cyclisation are considered, various modes of practical application are examined, and their prospects are noted. A list of 260 references is included.