Conjugated Polymers with Repeated Sequences of Group 16 Heterocycles Synthesized through Catalyst-Transfer Polycondensation

Periodic π-conjugated polymers
of the group 16 heterocycles
(furan, thiophene, and selenophene) were synthesized with controlled
chain lengths and relatively low dispersities using catalyst-transfer
polycondensation. The optical gap and redox potentials of these copolymers
were fine-tuned by altering the heterocycle sequence, and atomic force
microscopy revealed nanofibrillar morphologies for all the materials.
Grazing incidence wide-angle X-ray scattering of the thiophene-selenophene
copolymers indicated that the π-stacking distance increased
with incorporation of the larger heteroatom (from ∼3.7–4.0
Å), while the lamellar spacing decreased (from ∼15.8–15.2
Å). The study also revealed that periodic sequences allow electronic
properties to be tuned while retaining nanofibrillar morphologies
similar to those observed for poly­(3-hexylthiophene).