Synthesis and Modification of Polyphosphinoboranes and Polyborosiloxanes

Student thesis: Doctoral ThesisDoctor of Philosophy (PhD)

Abstract

This thesis describes synthetic routes to main group element-containing macromolecules through the polymerisation of inorganic monomers, and the modification of preformed polymers. Investigations into the use of polyphosphinoboranes as hydrogels and flame-retardants are also disclosed.
Chapter 1 gives an overview on main group polymers with a focus on strategies to synthesise polyphosphinoboranes, polysiloxanes, and polyborosiloxanes. Applications of these polymers and
related species are discussed including the formation of hydrogels featuring p-block elements.
Chapter 2 describes the post-polymerisation modification of poly(phenylphosphinoborane) via UV-light induced hydrophosphination of olefins giving access to P-di(organosubstituted) polymers. The formation of crosslinked gels and water-soluble polymers using this methodology was also studied.
Chapter 3 describes investigations into the dehydropolymerisation of phenylphosphine-borane (PhH2P·BH3) using CpFe(CO)2OTf and related precatalysts. These studies suggest that the
polymerisation takes place via a hybrid mechanism rather than purely chain-growth as was initially reported. The polymerisation of phosphine-boranes using non-metal precatalysts was also investigated.
Chapter 4 is split into two sections. The first describes the synthesis of hydrogels via UV-light induced reaction of polyphosphinoboranes with methacrylate and acrylate capped poly(ethylene glycol), and dimethacrylate crosslinkers. These gels were found to reversibly swell in water. The second describes
the use of polyphosphinoboranes as leach-resistant flame-retardant additives for cotton fabric. When fabric impregnated with polyphosphinoborane was exposed to a flame, the material was found to selfextinguish leaving a char material which contained phosphoric acid and boric acid.
Chapter 5 describes the synthesis of borosiloxane molecules and polymers via dehydrocoupling and demethanative condensation routes under mild, metal-free conditions. The reaction of dimethyl
phenylboronate with secondary silanes in the presence of tris(pentafluorophenyl)borane results in the formation of polymers featuring alternating boron and siloxane units in the main chain.
Chapter 6 provides a general outlook for the work reported in this thesis along with some potential avenues for future work.
Date of Award24 Mar 2020
Original languageEnglish
Awarding Institution
  • The University of Bristol
SupervisorIan Manners (Supervisor) & Charl F J Faul (Supervisor)

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