Polyphosphazenes combining dioxybiphenyl and butyl-amino substituents, a series with unusually high TGA residues and glass transition temperatures with negative deviation from additivity

The new copolymeric series {[NP(O2C12H8)]1−x[NP(NHBun)2]x}n (O2C12H8double bond; length as m-dash2,2′-dioxy-1,1′-biphenyl) with x = 0.1(1a), 0.31(1b), 0.43(1c), 0.63(1d) were prepared by the alkali carbonate-assisted sequential macromolecular substitution from [NPCl2]n. The thermal gravimetric analysis (TGA) revealed that although the stability decreased with x, the final residues (ca. 50% at 800 °C under N2; 30% at 900 °C under air; and 15% at 1100 °C under oxygen) were unusually high. The variation of the glass transition temperatures with x showed negative deviation from the additive values (Fox equation), probably due to the losing of hydrogen bonding contribution as x is decreased.