High‐temperature elastomers: A systematic series of linear poly(carborane‐siloxane)s containing icosahedral (CB10H10C) cages. I. Thermomechanical behavior in nitrogen

摘要

AbstractAn extensive study of structure–bulk property relations for a systematic series of well‐defined linear poly(carborane‐siloxane)s is reported. These polymers form the backbone components of the most recently developed high‐temperature elastomers. The basic structure iswhere (1)x= 1, 3, 4, 5, ∞; (2) A = endgroups (reactive and inert); (3)Z=meta‐, para‐carborane (forx= 3); (4) R = CH3, R = C2H4CF3(forx= 3), one in five R = C6H5with the remainder ∼CH3(forx= 4, randomly and regularly substituted); (5) molecular weight = ∼10,000, ∼50,000 (forx= 3). Thermomechanical spectra (∼1 cps) from −180°C to 625°C to −180°C in nitrogen at 3.6°C/min and thermogravimetric data from 25°C to 800°C in argon are presented. Physical transitions (Tg,Tm,Tcrys,Tsec) are discussed, including a correlation ofTgdata with structure (forx= 1, 2, 3, 4, 5, ∞) using a copolymer equation. Thermostability