Abstract
Main-chain-type liquid crystalline conjugated polymers and supramolecules are
discussed as hairy-rod-type polymers with rigid main chain and flexible covalently bonded side chains and as hairy-rod-type supramolecules with physically
bonded side chains. Thanks to the rigid main chain these materials show both
thermotropic and lyotropic liquid crystalline (LC) state which allows their facile
macroscopic alignment leading to anisotropic optical and electrical properties.
This chapter is a brief overview on this materials class with illustrative examples
including polyfluorene, polypyridine, and polythiophene.
Keywords
Conjugated polymers · Hairy-rod polymers · Hairy-rod supramolecules · Liquid
Crystallinity · Alignment · Polyfluorene · Polypyridine · Polythiophene
Definition
Liquid crystalline main-chain-type conjugated polymers consist of rigid main chains
and flexible side chains. These materials can be discussed in terms of hairy-rod
polymers and hairy-rod supramolecules and they manifest both lyotropic and thermotropic liquid LC states allowing facile macroscopic alignment.
Introduction
Electrically conductive and luminescent conjugated polymers and oligomers constitute the base for organic electronics (Baeg et al. 2013; Guo et al. 2013; Wang et al.
2012). Ionic conductivity, enhanced electrochemical activity, and specific interactions towards other chemicals are achieved through additional charged groups
incorporated into their structure (Jiang et al. 2009; Scherf 2011). Fig. 1 plots
chemical structures of conjugated polymers discussed in this chapter. These polymers are chemically simple and serve as model compounds for generalizations while
the device applications require further chemical modifications.
Liquid crystals (LC) other than conjugated polymers are thoroughly discussed
elsewhere in this book. Following the same principles (Akagi 2009; Bridges et al.
2017; Funahashi et al. 2008; Kuei and Gomez 2017; San Jose and Akagi 2013; Yang
and Hsu 2009), main-chain conjugated polymers exhibit thermotropic nature as
shown early for P1 (Tashiro et al. 1991) and lyotropic nature as shown for P2
(Wang et al. 1993) and P3 (Chen et al. 2004; Ou-Yang et al. 2005). LC state is
manifested in the nanometer length scale and stems from the main-chain stiffness,
while the atomic details, which are decisive for optoelectronic properties, play a
secondary role. This means that so far the LC behavior is concerned, we can learn
318
M. Knaapila et al.
Main-chain-type liquid crystalline conjugated polymers and supramolecules are
discussed as hairy-rod-type polymers with rigid main chain and flexible covalently bonded side chains and as hairy-rod-type supramolecules with physically
bonded side chains. Thanks to the rigid main chain these materials show both
thermotropic and lyotropic liquid crystalline (LC) state which allows their facile
macroscopic alignment leading to anisotropic optical and electrical properties.
This chapter is a brief overview on this materials class with illustrative examples
including polyfluorene, polypyridine, and polythiophene.
Keywords
Conjugated polymers · Hairy-rod polymers · Hairy-rod supramolecules · Liquid
Crystallinity · Alignment · Polyfluorene · Polypyridine · Polythiophene
Definition
Liquid crystalline main-chain-type conjugated polymers consist of rigid main chains
and flexible side chains. These materials can be discussed in terms of hairy-rod
polymers and hairy-rod supramolecules and they manifest both lyotropic and thermotropic liquid LC states allowing facile macroscopic alignment.
Introduction
Electrically conductive and luminescent conjugated polymers and oligomers constitute the base for organic electronics (Baeg et al. 2013; Guo et al. 2013; Wang et al.
2012). Ionic conductivity, enhanced electrochemical activity, and specific interactions towards other chemicals are achieved through additional charged groups
incorporated into their structure (Jiang et al. 2009; Scherf 2011). Fig. 1 plots
chemical structures of conjugated polymers discussed in this chapter. These polymers are chemically simple and serve as model compounds for generalizations while
the device applications require further chemical modifications.
Liquid crystals (LC) other than conjugated polymers are thoroughly discussed
elsewhere in this book. Following the same principles (Akagi 2009; Bridges et al.
2017; Funahashi et al. 2008; Kuei and Gomez 2017; San Jose and Akagi 2013; Yang
and Hsu 2009), main-chain conjugated polymers exhibit thermotropic nature as
shown early for P1 (Tashiro et al. 1991) and lyotropic nature as shown for P2
(Wang et al. 1993) and P3 (Chen et al. 2004; Ou-Yang et al. 2005). LC state is
manifested in the nanometer length scale and stems from the main-chain stiffness,
while the atomic details, which are decisive for optoelectronic properties, play a
secondary role. This means that so far the LC behavior is concerned, we can learn
318
M. Knaapila et al.