Polymerization of Cyclophosphazene Monomers

Attempts to polymerize the propenylfluorophosphazene monomer N3P3F5[C(Me)=CH2] by free-radical methods have not been successful (see Eq. 4.8) [19]. 

This was attributed to two features (1) The N3P3F5 group exerts a o-electron withdrawing effect on the vinyl group. (2) The vinyl monomer is sterically hindered as it has two substituents on the same carbon. One of these is the N3P3F5 group which is sterically encumbered. 

However, copolymerization of the monomers 4-6 with organic monomers such as styrene or methyl methacrylate was successful (Fig. 4.9) [19-21]. 

The following is the summary of the copolymerization behavior of the fluorocyclophosphazene monomers. 

The copolymers obtained are true copolymers and not a mixture of two homopolymers. This is indicated by the presence of a single glass transition temperature. For example, glass transition temperatures of polystyrene and poly(methylmethacrylate) are 100 and 114 °C. Single glass transition temperatures at 112 °C for polymer 19 (about 43% of cyclophosphazene) and 151 °C for polymer 20 (about 40% of cyclophosphazene) were detected. 

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