Abstract
The thermal polymerization behavior of cyclic trimeric phosphazenes that bear organosilylmethylene or organosiloxymethylene side groups, of general formula N3P3C15R, gem-N3P3C14R2, and gem-N3P3C15R(CH3)R, where R = CH2SiMe3, CH2SiMe2OSiMe3, and CH2Si(Me)(OSiMe2)3O, has been studied. Species N3P3Cl6CH2SiMe3, gem-N3P3C14(CH2SiMe3)2, and gem-N3P3C14(CH3)R undergo a phosphazene ring-opening polymerization to yield phosphazene high polymers that bear organosilicon side groups. However, those compounds of formula N3P3C15R and gem-N3P3C14R2 where R = CH2SiMe2OSiMe3 and CH2Si-(Me)(OSiMe2)3O undergo thermally induced PCH2-Si and Si-0 bond cleavage reactions in preference to polymerization. The neopentyl derivative, N3P3C15CH2CMe3, polymerized at 250 °C, but gem-N3P3C14-(CH3)(CH2CMe3) did not. However, both compounds copolymerized with their organosilicon counterpart, i.e., with N3P3C15CH2SiMe3 and gem-N3P3C14(CH3)(CH2SiMe3), respectively. Possible explanations for these results are presented. The high polymers formed by these reactions were treated with sodium trifluoroethoxide to yield derivatives in which the hydrolytically sensitive P-Cl bonds were replaced by stable P-OCH2CF3 units. Under certain conditions these substitutions resulted in the concurrent cleavage of the PCH2-Si side group bonds to yield P-CH3 units in their place. Use of this technique has allowed the first synthesis of the polymer [[NP(OCH2CF3)2]2-[NP(CH3)2]]n. The behavior of the cyclotetrasiloxane side group under siloxane polymerization conditions is also discussed. The characterization, structure, and properties of the high polymers are also described.
Original language | English (US) |
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Pages (from-to) | 1-10 |
Number of pages | 10 |
Journal | Macromolecules |
Volume | 21 |
Issue number | 1 |
DOIs | |
State | Published - Nov 1 1988 |
All Science Journal Classification (ASJC) codes
- Organic Chemistry
- Polymers and Plastics
- Inorganic Chemistry
- Materials Chemistry