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Title: Synthesis, structure, and properties of semi-fluorinated polymers
Author: Davidson, T. P.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 1997
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Abstract:
This thesis describes the synthesis main-chain and side-chain semi-fluorinated polymers by free radical and step growth techniques, and investigates trends in their thermal, solution and structural characteristics. Chapters 1 and 2 introduce liquid crystallinity and fluorinated materials and shows the liquid crystalline and structural behaviour of known fluorinated and semi-fluorinated materials. Chapter 3 describes the use of a free radical chain transfer polymerisation technique to synthesise polymer series with an alternating arrangement of fluorocarbon and hydrocarbon segments of varying length (FnRm (4), (6)). The thermal behaviour of these polymers was found to be quite complex and varied, a number of polymers with both short and longer fluorocarbon segments exhibiting mesophases, and multiple thermal transitions. An alternation of the transition temperatures with odd or even lengths of hydrocarbon segment was also observed. Structurally these materials are also complex, appearing to show an alternating packing arrangement with hydrocarbon packing against fluorocarbon. Chapter 4 details the synthesis of a polyester series with an alternating arrangement of fluorocarbon and hydrocarbon ester segments of varying length (FnRmPE (9)-(12)). The thermal characteristics of the polymers was more simple than the non-ester analogues, and liquid crystalline behaviour was not observed. The production of high molecular weight materials enabled the drawing of fibres, and X-ray diffraction of these showed a high number of reflections in most cases, with no obvious trend, indicating a very complex and varied packing behaviour. Finally, Chapter 5 investigates a series of amphiphilic semi-fluorinated polymers, synthesised by the same polyesterification technique, with varying hydrophilic ethylene oxide content (FOSAn (4), FOSPn (6), FSEGn (22)). The aim of the work was to try and facilitate water solubility with a view for use as a surfactant, but it was found that very high ethylene oxide content was required in order to approach water solubility rendering the use of ethylene oxide as the hydrophilic spacer non-viable. Polymers with shorter spacers were found to exhibit smectic A phases.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.598322  DOI: Not available
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