Thermal and Optical Properties of Regioregular Polythiophene Derivatives Containing Mesogenic Group in the Side Chain

Abstract

ABSTRACT:We synthesized regioregular liquid crystalline polythiophene (PTh) derivatives by chemical oxidative polymerization using iron trichloride to investigate the effect of the regioregularity on their physical properties. The regioregularity was about 90% for the PTh derivatives. A smectic phase was observed for two PTh derivatives. Plural peaks based on vibronic coupling characteristic of the regioregular PTh derivatives were observed in the π-π * transition absorption band of the UV-vis spectra. The vibronic coupling disappeared with increasing temperature and a new peak assigned to the PTh derivatives with non-planar conformation for the polymer backbone was observed in shorter wavelength range. The electrical conductivity was about 10 −3 -10

Enhanced Photoluminescence, Mesomorphism and Conformation of Liquid‐Crystalline Conjugated Polymers with Terphenyl Mesogen Pendants

“…Recently, a variety of polythiophenes containing liquidcrystalline cores and light-emitting chromophores have been prepared. [50,57,[110][111][112][113] Previously, we have synthesized a series of polythiophene derivatives with the mesogenic units directly attached to the main chain without spacers and found that no spacers between the bulky mesogenic pendant and the polythiophene backbone results in the loss of liquid-crystallinity. [114] Thus, Chen and co-workers have designed and synthesized a series of thiophene and polythiophene derivatives with flexible spacers by introducing terphenyl-containing mesogens into the 3-position of the thiophene (Scheme 5).…”

“…Attachment of chromophoric and mesogenic pendants to the polythiophene backbone may endow it with intriguing properties because its electrical and optical properties are expected to be controlled using molecular orientation of LC side chain. Recently, a variety of polythiophenes containing liquid‐crystalline cores and light‐emitting chromophores have been prepared 50, 57, 110–113. Previously, we have synthesized a series of polythiophene derivatives with the mesogenic units directly attached to the main chain without spacers and found that no spacers between the bulky mesogenic pendant and the polythiophene backbone results in the loss of liquid‐crystallinity 114.…”

Liquid Crystalline Polythiophene Bearing Phenylnaphthalene Side-Chain

“…Polythiophene derivatives have been drawing much attention for their wide-spreading potential of applications, such as organic light emitting diodes, − polymer solar cells, − and organic field effect transistors. , Therefore, they have also been investigated as π-conjugated backbone of the side-chain type polymer liquid crystals. For development of liquid crystallinity of polythiophenes, selective 2,5-polymerization of thiophene having mesogenic group at 3-position was crucial and several methods have successfully produced characteristic liquid crystalline polythiophenes, respectively. ,,− However, the excellent liquid crystalline polythiophenes, in which a fair percentage of insulating parts occupied, have faced a dilemma of sacrificing inherent electrical and optical properties of polythiophene. Replacement of the insulating side chains by semiconducting ones might be a solution and development strategy.…”

Liquid Crystalline Polythiophenes With Amphiphilic Side Chains

“…[1][2][3][4][5][6] Specifi cally, liquid crystalline (LC) polythiophene derivatives showing unique electrical and optical properties have been synthesized by transferring mesogenic units in the side chain or long alkyl groups to the polymer backbone. [7][8][9][10][11][12][13][14][15][16][17][18] For example, a polythiophene derivative bearing chiral LC mesogenic units and a fl uorine-containing asymmetric moiety showed ferroelectric behavior, whereas a polythiophene having 4-n -hexyloxy-2-hydroxybenzoate showed improved electric conductivity. [ 13 , 15 ] Previously, we reported that polythiophene derivatives having amphiphilic decyl-tri(oxyethylene) side groups could be used as a template for the formation of gold nanowire networks because of the amphiphilic liquid.…”