POLY(3-ETHER SUBSTITUTED THIOPHENE)S - STRUCTURES AND PROPERTIES

Poly(3-ether substituted thiophene)s are prepared from chemical oxidation with FeCl3 and have the structures: [GRAPHICS] where (i) X=H; Y=(-OC7H15) 1, (-O-(CH2)2-O-C4H9) 2, (-O-(CH2)-O-(CH2)-O-CH3) 3; (ii) X=CH3; Y=(-OC7H15) 4, (-O-(CH2)2-O-C4H9) 5; (iii) X=H; Y=(-CH2-O-C6H13) 6; (iv) X=H; Y=(-(CH2)2-O-C5H11) 7. The polymers of type (i) are crosslinked; only their oligomers are soluble. The polymer of type (iii) can not be obtained from its monomer by the present chemical method, since its monomer contains an allylic oxygen , which is easy to be attacked. The polymers of type (ii) and (iv) are soluble and have high molecular weight. FeCl3-doped polymer 7 at the doping level 0.04 is soluble and can be cast in to flexible free standing film with a conductivity of 10(-4) S/cm. Those with an oxygen atom in the repeated unit of the side chain (polymers 4 and 7) have lower conjugation length in solution and solid forms in comparison with poly(3-octylthiophene) (P3OT) and have no appreciable thermochromism. The oxidation potential of polymer 7 is 1.0 V/SCE which is comparable with that of P3OT (1.01 V/SCE). Polymer 5, which has two oxygen atoms in the repeated unit, has higher conjugation length (lambda max=535 nm) and lower oxidation potential (0.6 V/SCE) compared to P3OT (lambda(max)=500 nm, 1.01 V/SCE).