Polyphosphazene and molding compound containing the polyphosphazene

A polyphosphazene produced by a process comprising the steps a) and b):

• a) reaction of a cyclic phosphazene of formula (1)
• wherein k is a natural number between 1 and 10 with phenol in the presence of a base;
• and
• b) further reaction with an aromatic diphenol of formula (2)
• wherein
• R1 and R2 independently of one another represent H or C1- to C8-alkyl and
• X represents a single bond, C1- to C5-alkylene, C2- to C5-alkylidene, C5- to C6-cycloalkylidene, —O—, —SO—, —CO—, —S—, or —SO2—
• in the presence of a base,
• wherein the molar ratio of employed phenol to the employed cyclic phosphazene of formula (1) is in the range from 3.5:1 to 1:1, and wherein the molar ratio of employed phenol to the employed aromatic diphenol of formula (2) is in the range from 3:1 to 1:1.