Gw. Heffner et al., CHARACTERIZATION OF POLY(3-OCTYLTHIOPHENE) .1. MOLECULAR CHARACTERIZATION IN DILUTE-SOLUTION, Polymer engineering and science, 35(10), 1995, pp. 860-867
The poly(3-alkylthiophenes) are a class of electrically conducting pol
ymers which are of particular scientific and commercial interest due t
o their solubility and meltabillty. A series of poly(3-octylthiophene)
(P3OT) fractions having molecular weights in the range M(w) = 30,000
to 400,000 were generated by preparative gel permeation chromatography
(GPC). Although the polymer remained weakly aggregated when dissolved
in pure THF, the addition of an organic salt (1 wt.% tetrabutylammoni
um p-toluenesulfonate) resulted in complete molecular dissolution. We
were thus able to completely and consistently describe the polymer's s
ingle-chain properties using three dilute solution characterization me
thods: viscometry, GPC, and integrated light scattering. The molecular
weight dependence of the intrinsic viscosity and the radius-of-gyrati
on were established, and were characteristic of solutions near the the
ta condition, indicating poor solvent quality. Calculation of the pers
istence length from our data revealed that the polymer backbone is onl
y 2 to 3 times more rigid than common flexible polymers, despite its c
onjugated ring structure.