Synthesis,one‐ and two‐photon properties of poly[9,10‐bis(3,4‐bis(2‐ethylhexyl‐oxy)phenyl)‐2,6‐anthracenevinylene‐alt‐N‐octyl‐3,6‐/2,7‐carbazolevinylene]

The synthesis, one‐ and two‐photon absorption (TPA) and emission properties of two novel 2,6‐anthracenevinylene‐based copolymers, poly[9,10‐bis(3,4‐bis(2‐ethylhexyloxy)phenyl)‐2,6‐anthracenevinylene‐alt‐N‐octyl‐3,6‐carbazolevinyl‐ene] ( P1 ) and poly[9,10‐bis(3,4‐bis(2‐ethylhexyloxy)phenyl)‐2,6‐anthracenevinyl‐ene‐alt‐N‐octyl‐2,7‐carbazolevinylene] ( P2 ) were reported. The as‐synthesized polymers have the number‐average molecular weights of 1.56 × 10⁴ for P1 and 1.85 × 10⁴ g mol^?1 for P2 and are readily soluble in common organic solvents. They emit strong bluish‐green one‐ and two‐photon excitation fluorescence in dilute toluene solution (? _P1 = 0.85, ? _P2 = 0.78, λ_em( P1 ) = 491 nm, λ_em( P2 ) = 483 nm). The maximal TPA cross‐sections of P1 and P2 measured by the two‐photon‐induced fluorescence method using femtosecond laser pulses in toluene are 840 and 490 GM per repeating unit, respectively, which are obviously larger than that (210 GM) of poly[9,10‐bis‐(3,4‐bis(2‐ethylhexyloxy) phenyl)‐2,6‐anthracenevinylene], indicating that the poly(2,6‐anthracenevinylene) derivatives with large TPA cross‐sections can be obtained by inserting electron‐donating moieties into the polymer backbone. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 463–470, 2010     

Alternating copolymers of 2,6‐bis(p‐dihexylaminostyryl)anthracene‐9,10‐diyl and N‐octylcarbazole with large two‐photon cross sections

We report the synthesis, thermal, one‐ and two‐photon properties of poly(2,6‐bis(p‐dihexylaminostyryl)anthracene‐9,10‐diyl‐alt‐N‐octylcarbazole‐3,6‐/2,7‐diyl) ( P1/P2 ). The as‐synthesized polymers exhibit number‐average molecular weights of 1.7 × 10⁴ for P1 and 2.1 × 10⁴ g/mol for P2 . They emit strong one‐ and two‐photon excitation fluorescence with the peak around 502 nm, and the fluorescence quantum yields around 0.76 in chloroform. In film state, P1 and P2 show different red‐shift emission with the peaks at 512 nm and 523 nm, respectively. The DSC measurement reveals that as‐synthesized polymers are all amorphous aggregates with the glass transition temperatures of 131 °C for P1 and 152 °C for P2 . The solution two‐photon absorption (TPA) properties of P1 and P2 in chloroform are measured by the two‐photon‐induced fluorescence method using femtosecond laser pulses (120 fs). The TPA cross sections (δ) are measured over the range of 700–900 nm. The maximal δ of P1 and P2 all appear at ～800 nm and are 1010 GM and 940 GM per repeating unit, respectively. This suggests that no notable interactions among structure units that impair their fluorescence and TPA properties, and the polymers with large δ can be obtained by using the high TPA‐active units as building blocks. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

可溶性聚(2-甲氧基-5-辛氧基)对苯乙炔的合成及其导电和三阶非线性光学性能

聚对苯乙炔;电导率;三阶非线性极化率;简并四波混频;可溶性聚(2-甲氧基-5-辛氧基)对苯乙炔的合成及其导电和三阶非线性光学性能     

Efficient tuning nonlinear optical properties: Synthesis and characterization of a series of novel poly(aryleneethynylene)s co‐containing BODIPY

A series of novel conjugated poly(aryleneethynylene)s (PAEs) co‐containing BODIPY have been synthesized and characterized, and their third‐order nonlinear optical properties were studied using the Z‐scan technique. Interestingly, by introducing the BODIPY skeleton into the PAE backbone, the polymers showed that their nonlinear optical properties were dependent on the BODIPY component. From poly‐4 to poly‐1, the third‐order nonlinear optical properties of the polymers enhanced regularly with the increase of the BODIPY component of the copolymers, indicating that the BODIPY component played decisive roles in enhancing the nonlinear optical properties. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7401–7410, 2008     

Poly(4‐vinylpyridine) as the host ligand of metal‐containing chromophores for second‐order nonlinear optical active materials

Two formulas of grafted polymers with metal‐containing chromophores, potentially suitable for second‐order nonlinear optics applications, are described. Two chromophores were obtained from a tridentate ligand coordinated to Cu(II) or Pd(II) ions. The organometallic chromophore fragments were grafted to poly(4‐vinylpyridine) by the pyridinic nitrogen of the host polymer. Some qualities displayed by the new metallated polymers are remarkable: (1) a high value of the first hyperpolarizability coefficient of the chromophores, (2) a high content of the grafted chromophore in the polymers (up to 60 wt %), (3) a considerable increase in the glass‐transition temperatures (up to 240 °C), (4) good thermal stability in air (ca. 280 °C), and (5) good optical transparency of the films. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2987–2993, 2002     

Optical‐limiting and nonlinear optical polyacetylenes: Synthesis of azobenzene‐containing poly(1‐alkyne)s with different spacer and tail lengths

Poly(1‐alkyne)s containing azobenzene pendant groups with different lengths of the spacer and terminal alkyloxy group {? [HC?C(CH₂)_mOCO? C₆H₄? N?N? C₆H₄? OC_pH_2p+1]_n? , where m = 1, 2, 3, or 9 and p = 4, 7, or 12} were synthesized in satisfactory yields with the [Rh(nbd)Cl]₂–Et₃N catalyst. All the polymers were soluble in common organic solvents such as CHCl₃ and tetrahydrofuran. Their structures and properties were characterized and evaluated with IR, NMR, thermogravimetric analysis, UV, and optical‐limiting and nonlinear optical analyses. All the polymers were thermally stable and decomposed at temperatures as high as ～300 °C. The optical‐limiting and nonlinear optical properties of the polymers were sensitive to their molecular structures. Polymers having shorter spacer lengths and longer terminal groups showed better performances and larger third‐order nonlinear optical susceptibility (up to 1.34 × 10^?10 esu). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2346–2357, 2006     

Synthesis of π‐conjugated poly(dithiafulvene) by cycloaddition polymerization of aldothioketene from a bis(1,2,3‐thiadiazole) monomer

A π‐conjugated poly(dithiafulvene) ( 2 ) was obtained by the cycloaddition polymerization of aldothioketene with its alkynethiol tautomer derived from 1,4‐bis(1,2,3‐thiadiazolyl‐4‐yl)benzene ( 1 ) in a 94% yield. To a mixure of 1 and dimethyl sulfoxide (DMSO)/ethanol (5/1, v/v), KOH was added. After stirring the mixture overnight, piperidine was added to quench the terminal thioketenes. The reaction mixture was then poured into water to obtain the product. The cycloaddition polymerization of aldothioketene derived from 1 with its alkynethiol tautomer was studied under various conditions in several solvent systems. The structure of the polymer was supported by the ¹H NMR and ¹³C NMR spectra. The number‐average degree of polymerization (DP) of 2 was 8, estimated from the ¹H NMR analysis. Optical properties and electrochemical analysis of 2 were also studied. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5872–5876, 2004     

Conjugated and partially conjugated 2,5‐diphenylthiophene‐containing light‐emitting copolymers in polymeric light‐emitting diode (PLED) device fabrications

To study the effect of nonconjugation on polymeric and photophysical properties of thiophene‐containing polymers, new light‐emitting copolymers comprising either alternate 2,5‐diphenylthiophene and vinylene or alternate 2,5‐diphenylthiophene and aliphatic ether segments were synthesized. Both copolymers contained 2,5‐diphenylthiophene as the major chromophore and emitted a sky bluish fluorescence in dilute solution (10^?2 mg/mL). With a rigid and planarity structure and the concomitant crystallinity, the former copolymer (fully conjugated) possessed a higher quantum efficiency, a higher glass‐transition temperature, and a better thermal stability. In contrast, the latter copolymer (conjugated–nonconjugated) had better solubility and provided enhanced photophysical properties for the fabricated polymeric light‐emitting diode (PLED) device: at 15 V, the maximum current and brightness were 110 mA/cm² and 4289 cd/m², respectively, and the electroluminescence efficiency remained constant at approximately 4.9 cd/A in a voltage range of 8 to 14 V. The existence of intramolecular/intermolecular aggregates in the latter copolymer was corroborated from the the UV–vis and photoluminescence spectra of its solutions. With an increase in solution concentration, the shape and λ_max of the photoluminescence spectrum were redshifted. In a solution with a concentration as high as 10 mg/mL, the redshift was so drastic that the photoluminescence spectrum was nearly identical to that of a solid‐film. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6061–6070, 2004     

Oxidation polymerization of a charge‐transfer complex of 2,6‐bis(2‐thienyl)‐1,4‐dithiafulvene with 7,7,8,8‐tetracyanoquinodimethane

A π‐conjugated poly(α‐dithienylen‐dithiafulvene) ( 2 ) was obtained by the oxidation polymerization of 2,6‐bis(2‐thienyl)‐1,4‐dithiafulvene ( 1 ) as a dithiafulvene monomer derived from 4‐(2‐thienyl)‐1,2,3‐thiadiazole. When a solution of 1 in CHCl₃ was added to a stirred solution of FeCl₃ in CHCl₃, only the low‐molecular‐weight product 2 was obtained. The mixture was stirred for 15 h with an N₂ flow. The polymerization at higher temperatures resulted in polymers with large insoluble fractions. A higher molecular weight polymer was obtained by the oxidation polymerization of a charge‐transfer complex of 1 with 7,7,8,8‐tetracyanoquinodimethane (compound 3 ). In contrast to 2 , polymer 4 was readily soluble in dimethyl sulfoxide, dimethylformamide, and acetone and partially soluble in tetrahydrofuran and methanol and had a larger molecular weight (peak top molecular weight = 37,000). The conductivity of polymer 4 was 3 orders of magnitude larger than that of polymer 2 . © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6592–6598, 2005     

Complex formation and degradation in poly(acrylonitrile‐co‐vinyl acetate) containing copper nitrate

The pyrolysis of polymers containing metal nitrates may provide a relatively simple, rapid, and advantageous method of producing high‐temperature superconductors (HTSCs). The advantage lies in the ability to use conventional polymer processing or microlithographic patterning before pyrolysis. A copolymer of acrylonitrile and vinyl acetate [P(AN‐VA)], a well‐known fiber‐forming polymer, was investigated as a potential HTSC precursor. Complex formation with the highly polar acrylonitrile groups was expected to enhance atomic‐level mixing and hinder nitrate recrystallization. The metal nitrates were found to have a profound effect on P(AN‐VA) pyrolysis. P(AN‐VA) containing copper nitrate (CuN) exhibited complex formation and an exothermic decomposition that began at about 170 °C (reaction 1‐CuN). Reaction 1‐CuN had a heat of about 3.5 kJ/g_NO3 and a mass loss of about 0.99 g/g_NO3. As reaction 1‐CuN also involved the nitrile groups, it disrupted the nitrile cyclization reaction at about 290 °C. For a P(AN‐VA)/CuN ratio of 2/1, there was no nitrile cyclization, and the thermooxidative degradation temperature was reduced by approximately 200 °C. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1023–1032, 2004     

Polyfluorenes minimally doped with 1,4‐bis(2‐thienyl‐2‐cyanovinyl)benzene chromophore: Their synthesis,characterization, and application to white‐light‐emitting materials

Copolyfluorenes ( PFR1 and PFR2 ), chemically doped with 0.1 and 0.025 mol % 2,5‐dihexyloxy‐1,4‐bis(2‐thienyl‐2‐cyanovinyl)benzene (MR chromophere) were synthesized by the Suzuki coupling reaction. The PFR s were used to fabricate white‐light‐emitting devices through incomplete energy transfer. Because of the low content of the MR chromophore, the optical, thermal, and electrochemical properties of the PFR s were almost identical to those of polyfluorene, except for their photoluminescent (PL) and electroluminescent (EL) properties. The copolymer films showed PL peaks at about 428 and 570 nm originating from fluorene segments and MR chromophores, respectively. Compared with the model compound ( MR ), the polymer chains extended the conjugation length of the MR chromophores and exhibited a 20–48 nm red‐shift in the emission band. In addition, the lower LUMO level of the MR (?3.27 eV) was expected to improve the electron injection. The EL devices [ITO/PEDOT:PSS/ PFR s/Ca (50 nm)/Al (100 nm)] showed a broad emission band, covering the entire visible region, with chromaticity coordinates of (0.36, 0.35) and (0.32, 0.30) for PFR1 and PFR2 devices, respectively. The emission color of the PFR2 device was very similar to that of a pure white light (0.33, 0.33); and the maximal brightness and current efficiency were 3011 cd/m² and 1.98 cd/A, respectively, which surpass those found for polyfluorene devices (1005 cd/m², 0.28 cd/A). A). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3703–3713, 2008     

Novel Chromophore‐Functionalized Poly[2‐(trifluoromethyl) adamantyl acrylate‐methyl vinyl urethane]s with High Poling Stabilities of the Nonlinear Optical Effect

Nonlinear optical vinyl polymers with high glass transition temperature (T_g) were prepared by the functionalization of a fluorinated acrylate‐methyl vinyl isocyanate copolymer. A modified pathway to obtain a thiophene bridged chromophore was worked out. Poled films of the polymers show a fairly high and stable nonlinear optical response, even at elevated temperatures.

The thiophene‐bridged chromophore, based on a substituted dicyanomethylene‐dihydrofuran acceptor, synthesized here.     

Enhanced third‐order nonlinear optical properties determined in thin films using the Z‐scan technique: bis(μ‐4,4′‐oxydibenzoato)bis[(4′‐phenyl‐2,2′:6′,2′′‐terpyridine)cobalt(II)]

π‐Conjugated organic materials exhibit high and tunable nonlinear optical (NLO) properties, and fast response times. 4′‐Phenyl‐2,2′:6′,2′′‐terpyridine (PTP) is an important N‐heterocyclic ligand involving π‐conjugated systems, however, studies concerning the third‐order NLO properties of terpyridine transition metal complexes are limited. The title binuclear terpyridine Co^II complex, bis(μ‐4,4′‐oxydibenzoato)‐κ³O,O′:O′′;κ³O′′:O,O′‐bis[(4′‐phenyl‐2,2′:6′,2′′‐terpyridine‐κ³N,N′,N′′)cobalt(II)], [Co₂(C₁₄H₈O₅)₂(C₂₁H₁₅N₃)₂], (1), has been synthesized under hydrothermal conditions. In the crystal structure, each Co^II cation is surrounded by three N atoms of a PTP ligand and three O atoms, two from a bidentate and one from a symmetry‐related monodentate 4,4′‐oxydibenzoate (ODA²⁻) ligand, completing a distorted octahedral coordination geometry. Neighbouring [Co(PTP)]²⁺ units are bridged by ODA²⁻ ligands to form a ring‐like structure. The third‐order nonlinear optical (NLO) properties of (1) and PTP were determined in thin films using the Z‐scan technique. The title compound shows a strong third‐order NLO saturable absorption (SA), while PTP exhibits a third‐order NLO reverse saturable absorption (RSA). The absorptive coefficient β of (1) is −37.3 × 10⁻⁷ m W⁻¹, which is larger than that (8.96 × 10⁻⁷ m W⁻¹) of PTP. The third‐order NLO susceptibility χ⁽³⁾ values are calculated as 6.01 × 10⁻⁸ e.s.u. for (1) and 1.44 × 10⁻⁸ e.s.u. for PTP.     

Synthesis and opto‐electrical properties of dendron‐containing poly(2,3‐diphenyl‐1,4‐phenylenevinylene) derivatives

A new series of poly(2,3‐diphenyl‐1,4‐phenylenevinylene) derivatives containing dendritic side groups were synthesized. Different generations of dendrons were integrated on the pendant phenyl ring to investigate their effect on optical and electrical properties of final polymers. Homopolymers can not be obtained via the Gilch polymerization because of sterically bulky dendrons. By controlling the feed ratio of different monomers during polymerization, dendron‐containing copolymers with high molecular weights were obtained. The UV–vis absorption and photoluminescent spectra of the thin films are pretty close; however, quantum efficiency is significantly enhanced with increasing the generation of dendrons. The electrochemical analysis reveals that hole‐injection is also improved by increasing dendritic generation. Double‐layer light‐emitting devices with the configuration of ITO/PEDOT:PSS/polymer/Ca/Al were fabricated. High generation dendrons bring benefit of improved device performance. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3440–3450, 2007     

Synthesis and characterization of novel germanium‐containing poly(p‐phenylenevinylene) derivatives

Novel blue‐emitting germanium‐containing poly(p‐phenylenevinylene) (PPV) derivatives with well‐defined conjugation lengths were synthesized via Wittig‐condensation polymerizations. The polymers can be color‐tuned by the introduction of various chromophores into the PPV‐based polymer backbones. The photoluminescence (PL) spectra of the polymers, GePVK (containing carbazole moieties), GeMEH (containing dialkoxybenzene moieties), and GePTH (containing phenothiazine moieties), were found to exhibit blue, greenish blue, and green emissions, respectively. GePTH produces more red‐shifted emission than GeMEH and GEPVK, resulting in green emission, and the solution and solid state PL spectra of GePVK consist of almost blue emission. The electroluminescence spectra of GeMEH and GePTH contain yellowy green and yellow colors, respectively. Interestingly, GePVK exhibits white emission with CIE coordinates of (0.33, 0.37) due to electroplex emission in the light‐emitting diodes. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 979–988, 2008     

High‐performance amorphous donor–acceptor conjugated polymers containing x‐shaped anthracene‐based monomer and 2,5‐bis(2‐octyldodecyl)pyrrolo[3,4‐c]pyrrole‐1,4(2H,5H)‐dione for organic thin‐film transistors

New diketopyrrolopyrrole (DPP)‐containing amorphous conjugated polymers, such as poly(3‐(5‐((9,10‐bis((4‐hexylphenyl)ethynyl)‐6‐(prop‐1‐ynyl)anthracen‐2‐yl)ethynyl) thiophen‐2‐yl)‐5‐(2‐hexyldecyl)‐2‐(2‐octyldodecyl)‐6‐(thiophen‐2‐yl)pyrrolo[3,4‐c]pyrrole‐1,4(2H,5H)‐dione) ( 4 ), and poly(3‐(5‐((2,6‐bis((4‐hexylphenyl)ethynyl)‐10‐(prop‐1‐ynyl)anthracen‐9‐yl)ethynyl)thiophen‐2‐yl)‐2,5‐bis(2‐octyldodecyl)‐6‐(thio phen‐2‐yl)pyrrolo[3,4‐c]pyrrole‐1,4(2H,5H)‐dione) ( 7 ), were successfully synthesized via Sonogashira coupling reactions under microwave conditions. Copolymer 7 , incorporating a DPP moiety at the 9,10‐position of the anthracene ring through a triple bond, showed a much lower bandgap energy (E_g = 1.81 eV) than copolymer 4 (E_g = 2.13 eV). Tuning of the molecular frontier orbital energies was achieved by only changing the anchoring position of dithiophenyl‐DPP from the 2,6‐ to the 9,10‐position in the anthracene ring. Because of the donor–acceptor (D–A) interaction and the two‐dimensional planar structure of the X‐shaped donor monomer, the resulting polymers showed good interchain π?π stacking in the thin‐film state, despite being amorphous polymers. When the newly synthesized polymer 7 was used as a semiconductor material in an organic thin‐film transistor, the best mobility of up to 0.12 cm² V^?1 s^?1 (I_on/off = ～ 4.4 × 10⁶) was observed, which is one of the highest values recorded for amorphous polymer films reported to date. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

One donor–two acceptor (D–A1)‐(D–A2) random terpolymers containing perylene diimide,naphthalene diimide,and carbazole units

A series of one donor–two acceptor (D–A₁)‐(D–A₂) random terpolymers containing a 2,7‐carbazole donor and varying compositions of perylene diimide (PDI) and naphthalene diimide (NDI) acceptors was synthesized via Suzuki coupling polymerization. The optical properties of the terpolymers are weighted sums of the constituent parent copolymers and all show strong absorption over the 400 to 700 nm range with optical bandgaps ranging from 1.77 to 1.87 eV, depending on acceptor composition. The copolymers were tested as acceptor materials in bulk heterojunction all‐polymer solar cells using poly[(4,8‐bis‐(2‐ethylhexyloxy)‐benzo[1,2‐b;4,5‐b′]dithiophene)‐2,6‐diyl‐alt‐(4‐(2‐ethylhexanoyl)‐thieno[3,4‐b]thiophene)‐2,6‐diyl] (PBDTTT‐C) as the donor material. In contrast to the optoelectronic properties, the measured device parameters are not composition dependent, and rather depend solely on the presence of the NDI unit, where the devices containing any amount of NDI perform half as well as those using the parent polymer containing only carbazole and PDI. Overall this is the first example of a one donor–two acceptor random terpolymer system containing perylene diimide (PDI) and naphthalene diimide (NDI) acceptor units, and demonstrates a facile method of tuning polymer optoelectronic properties while minimizing the need for complicated synthetic and purification steps. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3337–3345     

Thermally‐Activated Pentanol Delivery from Precursor Poly(p‐phenylenevinylene)s for MEMS Lubrication

The synthesis of two new polyphenylene vinylene (PPV) precursor polymers which can be thermally induced to eliminate pentanol is presented. Pentanol has recently been discovered to be a very useful lubricant in MicroElectroMechanical Systems. The utilization of the elimination reaction of precursor polymers to PPV as a small molecule delivery platform has, to the best of our knowledge, not been previously reported. The elimination reactions were examined using thermal gravimetric analysis, gas chromatography, and UV–Vis spectroscopy. Using PPV precursors allows for (1) a high loading of lubricant (one molecule per monomeric unit), (2) a platform that requires relatively high temperatures (>145 °C) to eliminate the lubricant, and (3) a non‐volatile, mechanically and chemically stable by‐product of the elimination reaction (PPV).     

Synthesis and properties of azobenzene‐containing poly(1‐alkyne)s with different functional pendant groups

1‐Alkynes containing azobenzene mesogenic moieties [HC?C(CH₂)₉? O? ph? N?N? ph? O? R; R = ethyl ( 1 ), octyl ( 2 ), decyl ( 3 ), (S)‐2‐methylbutyl ( 4 ), or (S)‐1‐ethoxy‐1‐oxopropan‐2‐yl ( 5 ); ph = 1,4‐phenyl] were synthesized and polymerized in the presence of a Rh catalyst {(nbd)Rh⁺[B(C₆H5)₄]^?; nbd = 2,5‐norbornadiene} to yield a series of liquid‐crystalline polymers in high yields (e.g., >75%). These polymers had moderate molecular weights (number‐average molecular weight ≥ 12,000), high cis contents in the main chain (up to 83%), good thermal stability, and good solubility in common organic solvents, such as tetrahydrofuran, chloroform, and dichloromethane. These polymers were thoroughly characterized by a combination of infrared, nuclear magnetic resonance, thermogravimetric analysis, differential scanning calorimetry, polarized optical microscopy, and two‐dimensional wide‐angle X‐ray diffraction techniques. The liquid‐crystalline behavior of these polymers was dependent on the tail group attached to the azobenzene structure. Poly‐ 1 , which had the shortest tail group, that is, an ethyl group, showed a smectic A mesophase, whereas poly‐ 2 , poly‐ 3 , and poly‐ 5 , which had longer or chiral tail groups, formed smectic C mesophases, and poly‐ 4 , which had another chiral group attached to the azobenzene structure, showed a chiral smectic C mesophase in both the heating and cooling processes. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4532–4545, 2006