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Title: Synthesis of new low band gap polymers
Author: Hagan, A. J.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2003
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The novel 3,4-bis-(3',7'-dimethyloctyloxy)-thiophene (171) was synthesised among others and with the route conditions being optimised. An Ethylenedioxythiophene (EDOT) derivative with solubilising alkyl chain was achieved. The literature routes are lengthy, slow and inefficient so new routes were explored to this very useful monomer family. One is very promising and was developed to the penultimate step. The monomer was functionalised to give the 2,5-distannyl derivative for organometallic controlled polymerisation, (218). Various poly(3,4-dialkoxythiophenes) were synthesised. A 2,5-dibromo-3,4-dinitrothiophene is synthesised and new routes are explored towards 4H-cyclopenta(2,1-b;3,4-b')-dithiophene and its derivatives, CDT. Again the literature route is slow, inefficient and costly, with many synthetic difficulties. We finally managed to produce a reasonable amount of CDT (220) and solved most of the synthetic problems in the way. A potential route to CDT via 3,3'-dibromo-2,2'-dithiophene (230) looks promising. It could provide a quick way to this desirable monomer, but will need more work. Synthesis of a novel cyano esther and preparation for the functionalisation of CDT was undertaken and is described. In chapter 5 donor acceptor copolymers, in particular thiophene based, and their synthesis are reviewed briefly. The 2,5-dibromo-3,4-dinitrothiophene is copolymerised via Stille coupling with the 2,5-distannyl EDOT derivative with a solubilising long alkyl chain (218). The band gap of the polymer (268), as expected, is not extremely low at 1.7 eV. Ab initio molecular dynamics is used in chapter 6 to explore some of the polymers synthesised. It proves a reasonable qualitative method but needs more data.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available