D 2 ‐ m ‐carborane siloxanes. V. Structure–property relationships

D 2 ‐ m ‐decacarborane dimethylsiloxane has unusual thermal stability and resistance towards reversion, however, this material exhibits a crystalline phase, T m at 68°C. To obtain an elastomeric material, this crystallinity is disrupted by replacing 30 to 50% of the m ‐carborane with p ‐carborane moieties or by the incorporation of phenyl moieties on the polymer backbone. The latter approach is preferred since improved thermo‐oxidative stability accompanies this modification. Correlation of the glass transition temperature and thermo‐oxidative stability with the polymer structure are presented.