A Study of the Synthesis and Reactivity of Fluorinated Phosphazenes

Open Access
Author:
Pierce, Ian Christopher
Area of Honors:
Chemistry
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Harry R Allcock, Thesis Supervisor
  • Przemyslaw Maslak, Honors Advisor
Keywords:
  • Phosphazenes
  • Synthesis
  • Polymers
  • Fluorine
Abstract:
Polyphosphazenes have been studied extensively due to their wide range of unique properties. These polymers consist of an alternating phosphorous-nitrogen backbone and have been modified by a wide range of side groups to be useful in biomedical, electronic, and elastomeric applications, as well as others. The vast majority of these syntheses have relied upon poly(dichlorophosphazene) ([NPCl2]n) as the reactive intermediate to allow for the addition of the various substituents. These reactions are extremely complex, and it has become common practice to utilize hexachlorocyclotriphosphazene ([NPCl2]3), as a small molecule model for the high polymer reactions. However, these compounds have limitations, especially regarding substitutions with organometallic reagents. To overcome these limitations, it was hypothesized that a fluorinated version of these compounds might affect the reactivity in a way that would allow for substitution to occur with organometallic reagents. The fluorinated phosphazene compounds [NPF2]3 and [NPF¬2]n were successfully synthesized and used as reactive intermediates in substitution reactions with trifluoroethanol (TFE), resulting in [NP(OTFE)2¬]3 and [NP(OTFE)2¬]n, respectively. These products were analyzed and confirmed by 31P NMR. However, insolubility of the fluoropolymer in THF was still encountered at high molecular weights and only very low molecular weights of [NP(OTFE)2¬]n were recovered. Overall, the experiments performed and described in this thesis work provided important information about fluorinated phosphazenes, but there is still a lot of research to be done in order to take advantage of organometallic reagents and the unique properties they may bring to phosphazene materials.