Synthesis and properties of self organising semiconducting and luminescent polymers and model compounds

Oligothiophene-PEO-block-co-polymers and related model compounds have been synthesised and characterised. In the polymers well-defined oligothiophene blocks (with from two to six α,λ-linked thiophene sequences) were alternated with poly(ethylene oxide) blocks of narrow polydispersity. Model λ,λ-linked sexithiophenes were prepared carrying chiral, achiral, mono and narrow polydispersity monomethyl PEO substituents at their terminal alpha positions. All the products were soluble in common organic solvents and organic/aqueous solvent mixtures. UV/vis and fluorescence studies in solution indicated that the oligothiophene segments were molecularly dissolved in good solvents like chloroform. Aggregation of the oligothiophenes occurred in dioxane/water mixtures, consistent with observed shifts of the UV absorption maxima towards the blue and quenching of the fluorescence. An oligothiophene length of three thiophenes (terthiophene) was necessary for aggregation to be observed. The materials formed well-organised transferable monolayers at the air water interface.