The syntheses of siloxyl and hydroxyl chain end functionalized polystyrene and
poly(methyl methacrylate) by Atom Transfer Radical Polymerization (ATRP) were
effected by the following methods:
(a) α-Siloxyl functionalized polymers were prepared in quantitative yields via a
one-pot ATRP synthesis method for the polymerization of styrene or methyl
methacrylate using a new siloxyl functionalized initiator adduct, formed in situ by
the reaction of (1-bromoethyl)benzene with 1-(4-t-butyldimethylsiloxyphenyl)-1-
phenylethylene in the presence of CuBr/bpy or CuBr/PMDETA as catalysts in
diphenyl ether at 90 -110 oC. The polymerizations proceeded via controlled living
radical polymerization methods and α-siloxyl functionalized polymers with
predictable number average molecular weights (Mn = 1.8 x 103 - 17.40 x 103
g/mol), narrow molecular weight distributions (Mw /Mn = 1.03 - 1.41) and
regiospecificity of the functional groups were obtained in quantitative yields.
Similarly, the one-pot ATRP synthesis method for the preparation of
α-bis(siloxyl) functionalized polymers were effected by the initiation of styrene or
methyl methacrylate polymerization with a new bis(siloxyl) functionalized initiator
adduct, formed by the in situ reaction of 1,1-bis(4-t-butyldimethylsiloxylphenyl)-
ethylene with (1-bromoethyl)benzene in the presence of CuBr/bpy or CuBr/
PMDETA as catalytic systems in diphenyl ether at 90 -110 oC. Each
polymerization reaction proceeded via a controlled living fashion to afford
quantitative yields of the corresponding α-bis(siloxyl) functionalized polymers with
predictable number average molecular weights (Mn = 1.7 X 103 - 15.00 x 103
g/mol), narrow molecular weight distributions (Mw /Mn = 1.03 - 1.35) and good
control of chain end functionality.
The acid catalyzed hydrolysis of α-siloxyl and α-bis(siloxyl) chain end
functionalized polymers afforded the corresponding α-hydroxyl and
α-bis(hydroxyl) chain end functionalized polymers, respectively.
Polymerization kinetic data was employed to determine the controlled/living
character of each ATRP reaction leading to the formation of different siloxyl
functionalized chain end functionalized polymers. Polymerization kinetic
measurements show that the polymerization follows first order rate kinetics with
respect to monomer consumption and the number average molecular weight
increases with percentage monomer conversion, resulting in the formation of
polymers with narrow molecular weight distributions.
Thin layer chromatography (TLC), 1H and 13C Nuclear Magnetic Resonance
Spectrometry (NMR), Fourier Transform Infrared Spectroscopy (FTIR), Size
Exclusion Chromatography (SEC), Gas Chromatography (GC) and non -
aqueous titrations were used to determine the structures and purity of the siloxyl
functionalized initiator precursors as well as the siloxyl and hydroxyl
functionalized polymers.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:unisa/oai:uir.unisa.ac.za:10500/3927 |
| Date | 06 1900 |
| Creators | Mputumana, Nomfusi Augusta |
| Contributors | Summers, G.J. (Prof.) |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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