Аннотация:In this work, polycarboranosiloxanes (Mn = 25.5 – 31.3 kDa) with well-defined structures and with a various content of carborane moieties (2 – 15 wt. %) were obtained. The TGA and DSC methods were used to study their thermal properties and the rheological behavior of melts s was studied. It was found that as the content of carboranes in the structure of these polymers exceeds 9 wt. %, the crystallization of the siloxane chain is suppressed. Data of rheological studies indicate that phase separation occurs in such hybrid carboranosiloxane systems.