Adv Polym Sci (2014) 265: 1–38
DOI: 10.1007/12_2014_278
© Springer-Verlag Berlin Heidelberg 2014
Published online: 4 July 2014
Progress in the Synthesis of Poly
(3-hexylthiophene)
Prakash Sista and Christine K. Luscombe
Abstract Polythiophene synthesis has undergone a multitude of changes, starting
from the initial methods of acid-catalyzed polymerizations with low yields of
oligomeric polythiophenes to modern methods using transition metal-based catalysts that allow controlled synthesis of poly(alkylthiophene)s with high molecular
weight and regioregularity. The discovery of the opto-electronic properties of
conjugated polymers played a major role in this development. Further improvements such as externally initiated polymerization not only enabled the synthesis of
polymers that are almost 100% regioregular, but also gave the capability for in situ
synthesis of these polymers on substrates, which increases their applicability in
opto-electronic devices. This chapter summarizes developments in the methodology of polythiophene synthesis.
Keywords Controlled molecular weight Á Externally initated polymerization Á
Poly(3-hexylthiophene) Á Poly(alkylthiophene) Á Polythiophene Á Quasi-living
polymerization Á Regioregularity Á Star-shaped P3HT
Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1 Initial Synthetic Methods for Polythiophenes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 Poly(3-alkylthiophenes) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 Regioregularity in Poly(3-alkylthiophenes) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3 Synthesis of Regioregular Poly(3-alkylthiophene) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.1 Other Synthetic Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4 Mechanism of Grignard Metathesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . 11
5 External Initiation of Polymerization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
P. Sista and C.K. Luscombe (*)
Department of Materials Science and Engineering, University of Washington, Seattle,
WA 98195-2120, USA
e-mail: luscombe@uw.edu
DOI: 10.1007/12_2014_278
© Springer-Verlag Berlin Heidelberg 2014
Published online: 4 July 2014
Progress in the Synthesis of Poly
(3-hexylthiophene)
Prakash Sista and Christine K. Luscombe
Abstract Polythiophene synthesis has undergone a multitude of changes, starting
from the initial methods of acid-catalyzed polymerizations with low yields of
oligomeric polythiophenes to modern methods using transition metal-based catalysts that allow controlled synthesis of poly(alkylthiophene)s with high molecular
weight and regioregularity. The discovery of the opto-electronic properties of
conjugated polymers played a major role in this development. Further improvements such as externally initiated polymerization not only enabled the synthesis of
polymers that are almost 100% regioregular, but also gave the capability for in situ
synthesis of these polymers on substrates, which increases their applicability in
opto-electronic devices. This chapter summarizes developments in the methodology of polythiophene synthesis.
Keywords Controlled molecular weight Á Externally initated polymerization Á
Poly(3-hexylthiophene) Á Poly(alkylthiophene) Á Polythiophene Á Quasi-living
polymerization Á Regioregularity Á Star-shaped P3HT
Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1 Initial Synthetic Methods for Polythiophenes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 Poly(3-alkylthiophenes) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 Regioregularity in Poly(3-alkylthiophenes) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3 Synthesis of Regioregular Poly(3-alkylthiophene) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.1 Other Synthetic Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4 Mechanism of Grignard Metathesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . 11
5 External Initiation of Polymerization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
P. Sista and C.K. Luscombe (*)
Department of Materials Science and Engineering, University of Washington, Seattle,
WA 98195-2120, USA
e-mail: luscombe@uw.edu