HDR Seminar: Karen Hakobyan – School of Chemistry HDR Seminar: Karen Hakobyan – School of Chemistry

HDR Seminar: Karen Hakobyan

Monday, 20 September 4:00pm – 4:45pm (30 minute presentation + 15 minutes of questions)

This seminar will be delivered via Zoom – Please email chemistry.researchsupport@sydney.edu.au for zoom link and password.

Speaker: Ms Karen Hakobyan

Host: Dr Markus Muellner & A/Prof. Christopher McErlean

Title: Controlled Polymer Photosynthesis

Abstract: Current polymer science research is moving towards the study of well-defined macromolecules with greater applications such as in biological systems, hybrid materials or photonics. Underlying to this move are synthesis methodologies which are robust, operate under mild reaction conditions and chemoselective, while maintaining the control over various possible parameters of macromolecular structure (i.e., molecular weight distribution, end groups, architecture, composition and sequence). Applying photocatalysis, in particular, heterogeneous photocatalysis, in reversible deactivation radical polymerisation (RDRP) offers an attractive means to controlled polymer synthesis.

In the first instance, we found that bismuth oxide photocatalysis can facilitate RAFT polymerisation. We also show that the normal molecular weight, end group, and composition control, normally associated with RAFT, were uncompromised in this process. This provided a solid ground for introducing heterogeneous photocatalysis into controlled polymer synthesis.

During our attempts to expand this idea to copper-free photoATRP, we found that ATRP initiation with RAFT propagation could be combined in one pot using bismuth oxide photocatalysis to obtain a controlled polymerisation. An end group modularity was thus introduced into RAFT polymerisation. This not only allowed for a wider scope of functionality to be introduced into the end groups (such as peptides) but also allowed for a continuous tuning of the molecular weight distribution spread.

Taking this study further, when the ATRP initiating component was neglected, we encountered a more “skeletal” variant of RAFT with an end group symmetry but with asymmetric propagation. This granted a unique block sequence control of both linear and cyclic polymers upon post-polymerisation modifications of the end groups.

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