Synthesis of Arborescent Amphiphilic Copolymers
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Date
2013-01-25T18:13:47Z
Authors
Alzahrany, Yahya
Journal Title
Journal ISSN
Volume Title
Publisher
University of Waterloo
Abstract
Living anionic polymerization techniques were applied to the synthesis of arborescent (dendritic)
well-defined graft polymers having core-shell morphologies, with a hydrophobic core and a
hydrophilic shell. Cycles of polystyrene substrate acetylation and anionic grafting yielded
successive generations of arborescent polystyrenes. The anionic polymerization of styrene with
sec-butyllithium provided polystyryllithium serving as side chains. These were coupled with a
linear acetylated polystyrene substrate to obtain a generation zero (G0) arborescent polymer. An
analogous G0 hydroxyl-functionalized polystyrene substrate with hydroxyl end groups was also
obtained by a variation of the same technique, using a bifunctional organolithium initiator
containing a hydroxyl functionality protected by a silyl ether group to generate the polystyrene
side chains. These were coupled with the linear acetylated polystyrene substrate and subjected to
a deprotection reaction to give the G0 polymer functionalized with hydroxyl groups at the chain
ends. A similar procedure was used to generate a hydroxyl-functionalized arborescent G1
polymer from the corresponding G0 acetylated polystyrene substrate. The growth of polyglycidol
chain segments was attempted from the hydroxyl-functionalized cores, to form a hydrophilic
shell around the hydrophobic cores, but led to extensive degradation. A click reaction was also
developed to synthesize the amphiphilic copolymers and was much more successful. In this case
alkyne-functionalized arborescent polystyrene substrates, obtained by a modification of the
hydroxyl-functionalized arborescent polystyrenes, were coupled with azide-functionalized
polyglycidol side chains.
Description
Keywords
arborescent polystyrene-graft-polyglycidol copolymers, arborescent amphiphilic