A new series of poly(organophosphazenes) with phenyl groups bonded to the skeleton has been prepared by the polymerization of phenylhalogenocyclotriphosphazenes. In addition, evidence about the mechanism of chlorophosphazene polymerization has been obtained by halogen scrambling studies. 1-Phenyl-1, 3, 3, 5, 5-pentachlorocyclotriphosphazene, N3P3Cl5Ph (5a), undergoes a ring-opening thermal polymerization at 250 °C. The resultant high polymer reacts with sodium trifluoroethoxide, sodium phenoxide, or piperidine to yield poly(organophosphazenes) that are free from P-Cl bonds. 1-Phenyl-1-bromo-3, 3, 5, 5-tetrachlorocyclotriphosphazene, N3P3Cl4BrPh (5b), also polymerizes at 250 °C but with scrambling of the bromine atoms between different phosphorus sites. The trimer, 5b, itself undergoes halogen scrambling at temperatures as low as 178 °C. The cyclophosphazenes, 5a and 5b, copolymerize at 250 °C with (NPC12)3. The copolymerization of 5a and N3P3Cl5Me provides a method for the synthesis of phosphazene polymers that bear both alkyl and aryl substituent groups. The trimers, 5b and N3P3Cl4BrMe, are accelerators for the polymerization of (NPC12)3 at 250 °C, while 5a and N3P3Cl5Me are weak inhibitors. However, polymers prepared in the presence of these inhibitors had molecular weights similar to those prepared from pure (NPC12)3 or in the presence of the accelerators. The mechanistic implications of these results are discussed.
All Science Journal Classification (ASJC) codes
- Organic Chemistry
- Polymers and Plastics
- Inorganic Chemistry
- Materials Chemistry