The synthesis and applications of phosphazene-containing polymers

The work described in this thesis focuses on the synthesis of new phosphazene containing polymers. The first section concerns the development of polymer electrolytes for use in rechargeable lithium batteries. This research has revolved around the development, synthesis and testing of novel materials as solid polymer electrolytes, the application of ring opening metathesis polymerization to phosphazene systems, the fabrication of polyphosphazenes with improved mechanical stability and flame retardance for use in gel polymer electrolytes, and the design and synthesis of a non-volatile, fire resistant additive for incorporation into gel polymer electrolytes.; The polymers developed include four co-substituted linear phosphazene polymers with controlled ratios of oligoethyleneoxy and trifluoroethoxy side groups synthesized as models for gel electrolyte systems with improved dimensional stability. A second series of linear polyphosphazenes were co-functionalized with oligoethyleneoxy groups (to provide a path for the conduction of ions) and aryloxy groups (to improve the mechanical properties and fire retardance). Two different polymer structures were prepared: cosubstituent polymers of the general structure [NP((OCH₂CH₂)_xOCH ₃)(OC₆H₅)]_n and single-substituent polymers of the general structure [NP(OC₆H₄O(CH ₂CH₂O)_xCH₃)₂]_n. The third series of polymers prepared are polynorbornenes with pendent cyclotriphosphazene side units that bear oligoethyleneoxy substituents. This work illustrates the application of ring-opening metathesis polymerization (ROMP) to phosphazene chemistry as well as lithium ion conduction. All of these systems were evaluated as electrolyte materials.; The second aspect of this work is the synthesis of well-defined cyclolinear phosphazene-containing polymers via acyclic diene metathesis (ADMET). The synthesis and characterization of cyclic phosphazene dienes, their subsequent polymerization, and the range of polymer properties achievable through variation of the phosphazene substituents is described. These are the largest monomers polymerized via this route, and the effects of different functional groups on the phosphazene ring are discussed. The non-polymerizable substituents were varied to include phenoxy, benzyloxyphenoxy, methoxyethoxyethoxy, and dimethylamino groups. The length of the polymerizable alkene chains was varied in length from three carbons to eleven carbons, and the polymerization of these monomers as well as their copolymerization with 1,9-decadiene is described. Additional polymer structures are studied after hydrogenation of the polymer backbones to yield fully saturated systems.