Year: 2013
Type: dissertation
Abstract: Living anionic polymerization techniques were applied to the synthesis of arborescent (dendritic) \nwell-defined graft polymers having core-shell morphologies, with a hydrophobic core and a \nhydrophilic shell. Cycles of polystyrene substrate acetylation and anionic grafting yielded \nsuccessive generations of arborescent polystyrenes. The anionic polymerization of styrene with \nsec-butyllithium provided polystyryllithium serving as side chains. These were coupled with a \nlinear acetylated polystyrene substrate to obtain a generation zero (G0) arborescent polymer. An \nanalogous G0 hydroxyl-functionalized polystyrene substrate with hydroxyl end groups was also \nobtained by a variation of the same technique, using a bifunctional organolithium initiator \ncontaining a hydroxyl functionality protected by a silyl ether group to generate the polystyrene \nside chains. These were coupled with the linear acetylated polystyrene substrate and subjected to \na deprotection reaction to give the G0 polymer functionalized with hydroxyl groups at the chain \nends. A similar procedure was used to generate a hydroxyl-functionalized arborescent G1 \npolymer from the corresponding G0 acetylated polystyrene substrate. The growth of polyglycidol \nchain segments was attempted from the hydroxyl-functionalized cores, to form a hydrophilic \nshell around the hydrophobic cores, but led to extensive degradation. A click reaction was also \ndeveloped to synthesize the amphiphilic copolymers and was much more successful. In this case \nalkyne-functionalized arborescent polystyrene substrates, obtained by a modification of the \nhydroxyl-functionalized arborescent polystyrenes, were coupled with azide-functionalized \npolyglycidol side chains.
Source: UWSpace (University of Waterloo)
Author: Yahya Alzahrany
Language: English
Subfield: Organic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2528278377