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Title: Application of radioisotopes to polymer chemistry : investigation of radiolabelled atom transfer polymerization
Author: Long, Mark
ISNI:       0000 0004 5369 4747
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2016
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The use of the radioisotope 14C in polymer chemistry has been reviewed, showing how it has been used to investigate the mechanistic aspects of free radical polymerizations, and the use of polymers in other scientific disciplines such as environmental, physical, chemical and medical sciences. An overview of the application of fluorescent spectroscopy to polymer chemistry is also reported. It covers the fundamentals of fluorescence chemistry, its application and the potential problems of the use of fluorescent labels in polymer chemistry. The application of radioisotopes to atom transfer radical polymerisation (ATRP) to investigate the fate of initiators used in the ATRP of 2-hydroxypropyl methacrylate (2- HPMA) is also reported. By using 14C radiolabelled initiators, radio thin layer chromatography (Radio TLC) and the liquid scintillation counting of fractions, collected from gel permeation chromatography (GPC), the fate of the initiating species where monitored during the polymerization of samples of 14C poly(2-HPMA), with degrees of polymerization of 10, 25 and 50 was assessed. GPC and Radio TLC, data showed that there was an under-utilisation of the initiator, 16% clearly observable at high monomer conversion (>97%), which could result in the initiation of new chains at monomer conversions of >90% and as late as 300 minutes after the polymerisation had started. These results contradict ATRP theory which states all initiator is consumed immediately at the commencement of the polymerization. 14C poly(2-HPMA) was also used to determine the efficiencies of the polymer purification methods, flash chromatography and precipitation. Although repeated precipitation increased fractionation, it was shown to be superior to flash chromatography in removing residual unreacted or terminated initiator. Finally, the possible effects of fluorescent labels on adsorption of low molecular weight 14C poly(DEAEMA) onto real surfaces (filter paper, photo graphic paper and hair) from aqueous solutions at pH=2 were investigated. Three low molecular weight samples of 14C poly(DEAEMA) were prepared by ATRP using 14C labelled initiators synthesized from alcohols of increasing hydrophobicity i.e. methyl, benzyl and 9-hydroxyfluorene (fluorescent label). The levels of adsorption were determined using phosphor imaging, oxidation of organic samples and liquid scintillation counting. Results indicated that differences in the chemistry of the polymer end groups can affect adsorption of the 14C poly(DEAEMA) and polymer assembly at the air/water interface. There was greater adsorption of polymers with a fluorescent end group. The increasing deposition was attributed to the increasing hydrophobicity of the polymer end group. Moreover, the controlled placement of one fluorescent label per polymer chain can influence the polymer’s properties, prompting the question, is the use of fluorescent groups to assess polymer behaviour and properties viable?
Supervisor: Not available Sponsor: Unilever Research & Development
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Atom Transfer Radical Polymerization ; Radioisotopes Radioactive Fluorescent ; Radiolabelled Deposition Initiators Radiosynthesis