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Polygermane Block Copolymers: Synthesis, Self-Assembly, and Applications in Nanotechnology

Final Report Summary - PARIM (Polygermane Block Copolymers: Synthesis, Self-Assembly, and Applications in Nanotechnology)

The goals of the project were to develop polygermane containing block copolymers and to study the self-assembly of the block copolymers. There were problems in the synthesis of the polygermane precursors using the routes described in my original proposal. Numerous approaches to create polygermane precursors were tried throughout the duration of the fellowship.

Concurrent to the polygermane work, research on the block copolymer self-assembly of related silicon and germanium containing ferrocene polymers was being performed. This research has produced significant scientific results which have been accepted for publication in top tier, high impact journals.

A goal of the proposal was to study the self-assembly of block copolymers. During the course of the fellowship, exciting, novel methods to improve control over the block copolymer self-assembly process were developed. Specifically, we have shown that micelle coronal crosslinking is a valuable tool to manipulate block copolymer self-assembly.

Highlights include:

1) Pt(0) was found to be an excellent reversible crosslinker for polyisoprene (PI) containing block copolymer micelles. Platinum(0) coordinates to unsaturated units within the PI, linking corona chains together to form a crosslinked network. The nature of the Pt-alkene interaction allows for this crosslinking to be reversed by the addition of a phosphine, which competitively binds to the platinum. This is the very first example of a reversible crosslinking system for polyisoprene and was recently published (J. Am. Chem. Soc. 2011, 133, 16 947 - 16 957).
2) Corona crosslinking of cylindrical block copolymer micelles was also found to be an excellent method to control micelle self-assembly. Using selective corona crosslinking, I have been able to direct the formation of non-centrosymmetric micelles. Given the significance of this work, it has been published in the journal Science (2012, 337, 559 - 562).

In addition to this original research, an extensive 23 page review on block copolymers and their emerging applications was published (Angew. Chem. Int. Ed. 2012, 51, 7898 - 7921).

The proposed transfer of knowledge objectives progressed well throughout the duration of the fellowship. Working in the Manners group, Dr Rupar has gained significant experience in the areas of polymer synthesis, self-assembly, and characterisation of nanoscale objects. Through the supervision of graduate students, Dr Rupar has been able to transfer knowledge and skill sets to the students.

Dr Rupar participated in EU-based polymer conferences in Bayreuth, Germany and Warwick, UK and established collabourative contacts within the EU that will be maintained in his future.

The work completed during the course of this fellowship has made a significant impact on the field of block copolymer self-assembly. The discovery of being able to precisely control block copolymer self-assembly through corona crosslinking is expected to have long term influences in the field of polymer chemistry. As a measure of the impact of Dr Rupar's work, his research was highlighted in the popular scientific press (Science 2012, 337, 530 and Chemical & Engineering News, 2012, 90, 39).

As a result of activities made possible by this fellowship, Dr Rupar has obtained a faculty position at the University of Alabama (USA).