Copolymerisation of Phenyl Isocyanate

The copolymerisation of ethylene oxide and phenyl isocyanate has been found [266] to proceed in the presence of the triethylaluminium-water (2 1) catalyst, although phenyl isocyanate alone could not be polymerised by the same catalyst. The copolymer formed was characterised by an alternating comonomer distribution [scheme (39)] and contained acetalic units in its chains (Table 9.4)  

The structure of the acetalic copolymer indicates that the carbonyl group of phenyl isocyanate is involved in the copolymerisation. This is connected with the presence of the phenyl substituent at the isocyanate nitrogen atom. Thus, alternating coordinations of comonomers via oxygen atoms of the isocyanate carbonyl group and the oxirane, followed by coordinating comonomer enchainments, have been postulated to take place throughout the copolymerisation [266]. 

The coordination polymerisation of carbonyl monomers by their carbonyl group concerns mostly acetaldehyde, trichloroacetaldehyde, propionaldehyde and butyraldehyde. One basic problem with all polyaldehydes, and especially with polyketones, is not the polymerisation itself but the stabilization of resulting polymers (or copolymers) against thermal degradation. 

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