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Abstract

This thesis outlines a comprehensive study of anionic polymerization of phosphaalkenes, encompassing both mechanistic and synthetic studies. The similarities between P=C and C=C bonds make the polymerization of phosphaalkenes a promising method for synthesizing novel phosphorus-containing polymers. Understanding the mechanism of phosphaalkene polymerization is crucial for optimizing the properties and applications of material derived from these novel monomers. These polymers could be potentially used as flame retardant materials. Through detailed kinetic analyses and the synthesis of key intermediates, this research provides valuable insights into the polymerization process. Chapter 1 introduces the background and functionality of low-coordinated phosphorus compounds. In the same, a detailed review of phosphorus-containing polymers is provided. Chapter 2 describes a series of poly(methylenephosphine)s (PMP) homo- and block co-polymers with styrene with different molecular weights. The physical properties, and glass transition temperatures (Tg), of the resulting polymers, were studied. All homo- and co-polymers displayed a single Tg in their DSC chromatograms with the transition temperature for the copolymers being in between those of the corresponding homopolymers. In Chapter 3, the goal was to study the propagation mechanism associated with the anionic polymerization of phosphaalkene. Non-polymerizable CH₂=CPh₂ was reacted with Li[MesP(Bu)–CPh₂] (and related species) to mimic the propagation step in polymerization. However, a very interesting cyclization reaction was observed during this study, which is consistent with the hypothesized mechanism of polymerization, involving the activation of the o-CH₃ moiety of the P-Mes (or m-Xyl) substituent. The initiation step for the anionic polymerization of a phosphaalkene was studied via molecular models in Chapter 4. For the first time, the putative propagating species, [MesP(Bu)–CPh₂]⁻, was isolated and studied. Additionally, the polymerization mechanism was re-examined by conducting a detailed kinetic analysis. Inspired by the study in Chapter 3, an isomerization addition-reversible cyclization mechanism for the anionic polymerization of phosphaalkene was proposed. Chapter 5 provides a summary of the work contained within this thesis, and future directions for these projects are postulated.