Poly(n-(3-thienyl)alkanesulfonates) (P3TAS's) containing propanesulfon
ate, hexanesulfonate, and octanesulfonate substituents have been prepa
red by oxidative coupling using ferric chloride. The ratio of head-to-
tail dyads to head-to-head dyads is 4:1. The extent of pi-conjugation
in the polymers, as determined by UV-vis spectroscopy, is relatively i
ndependent of:whether the polymers are in solution or in the solid sta
te. Polymer films of the sodium salt and sulfonic acid forms are amorp
hous in contrast to non-sulfonated analogs, i.e., the poly(3-alkylthio
phenes), which self-organize into semicrystalline solids. Morphologica
l differences between alkane and alkanesulfonate derivatives of polyth
iophenes are explained on the basis of ion aggregation which prevents
polymer chains from achieving the coplanar conformation required for c
rystallization. Remarkably, the acid form of the polymers, termed ''se
lf-doped'', exhibit electronic conductivities in the range 5 x 10(-2)-
10(-1) S/cm even though they too are amorphous and devoid of long rang
e order. The photochemistry of P3TAS's, in both their sodium salt and
''self-doped'' form, was investigated. The primary photochemical proce
ss is photosensitization and reaction of singlet oxygen, which leads t
o photobleaching, In oxygenated solutions, P3TAS's are much more photo
stable than their non-sulfonated analogs due to quenching of photosens
itized singlet oxygen by water. Films of P3TAS's take up atmospheric m
oisture in ambient air and, as a result, exhibit enhanced photostabili
ty compared td their non-sulfonated analogs exposed to ambient conditi
ons. Anhydrous films,. however, exhibit rates of photobleaching which
are comparable to the poly(3-alkylthiophenes). The acid form of the po
lymers is found to be more photostable than their corresponding sodium
salts. Unlike their non-sulfonated analogs, irradiated films of P3TAS
's exposed to ambient atmosphere do not cross-link to form insoluble P
olymer upon irradiation due to the presence of residual moisture. Howe
ver, photolithography can be performed on polymer films oxidized with
ferric chloride. Anhydrous films of P3TAS's are rendered insoluble upo
n exposure to UV or visible irradiation, thus affording the deposition
of negative polymer images.