Novel poly[3-(p-substituted)benzoyl-2,5-thiophenes] via nickel(0)-catalyzed coupling polymerization
Three novel poly[3-(p-substituted)benzoyl-2,5-thiophene]s (Ib, IIb, and IIIb) were successfully prepared via nickel(0)-catalyzed coupling polymerization of 3-benzoyl-2,5-dichlorothiophene (Ia), 3-(p-fluoro)benzoyl-2,5-dichlorothiophene (IIa), and 3-(p-toluoyl)-2,5-dichlorothiophene (IIIa). To our knowledge, monomers (IIa) and (IIIa) are new compounds. On the basis of K and α values from the Mark-Houwink relationship, the 〈Mv〉 of the polymers were in the range 1.50 × 105 to 3.51 × 105 g/mol. The α value equal to 0.97 is close to unity indicating that the 〈Mv〉 is approximately equal to the 〈Mw〉. The high molecular weight polymers were soluble in common organic solvents. Their glass transition temperatures were all above 160 °C and showed no evidence of crystallinity by differential scanning calorimetry. All three polymers were thermally and thermooxidatively stable with 10% weight loss in nitrogen and air occurring above 430 °C. The UV-vis absorption λmax for the three polymers greater than 465 nm is a further evidence of the high molecular weight and the long effective conjugation length.
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