Incorporation of cyclic phosphazene trimers into saturated and unsaturated ethylene-like polymer backbones

The synthesis of well-defined cyclolinear phosphazene polymers via acyclic diene metathesis (ADMET) has been demonstrated. This work extends the range of properties achievable in cyclolinear phosphazenes synthesized via ADMET and provides an assessment of the synthetic limitations. A series of tetraphenoxy and tetramethoxyethoxyethoxy functionalized phosphazene trimers have been synthesized that bear two alkene side chains, which together form the diene structure necessary for ADMET. The alkene chains vary in length from three carbons to 11 carbons. This has allowed the influence of the negative neighboring group effect to be examined as well as steric factors as they apply to the metathesis of phosphazene monomers. Moreover, the role of different catalysts is discussed together with the influence of the nonolefinic phosphazene substituents on the reactivity of the monomers. The influence on bulk polymer properties of the incorporation of different amounts of cyclic phosphazene per average polymer chain, through copolymerization studies with decadiene, is also discussed.