High‐molecular‐weight side‐chain liquid‐crystalline polyethers based on 4′‐cyanobiphenyl‐4‐oxy mesogenic groups

A set of poly[ω‐(4′‐cyano‐4‐biphenyloxy)alkyl‐1‐glycidylether]s were synthesized by the chemical modification of the corresponding poly(ω‐bromoalkyl‐1‐glycidylether)s with the sodium salt of 4‐cyano‐4′‐hydroxybiphenyl. New high‐molecular‐weight side‐chain liquid‐crystalline polymers were obtained with excellent yield and almost quantitative degree of modification. All side‐chain liquid‐crystalline polymers were rubbers soluble in tetrahydrofuran. The characterization by ¹H and ¹³C NMR revealed no changes in the regioregular isotactic microstructure of the starting polymer and the absence of undesirable side reactions such as deshydrobromination. The liquid crystalline behavior was analyzed by DSC and polarized optical microscopy, and mesophase assignments were confirmed by X‐ray diffraction. Polymers that had alkyl spacers with n = 2 and 4 were nematic, those that had spacers with n = 6 and 8 were nematic cybotactic, and those that had longer spacers (n = 10 and 12) were smectic C and showed some crystallization of the side alkyl chains. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3002–3012, 2004     

Facile green strategy for micro/nano structured conducting polyaniline‐clay nanocomposite via template polymerization using amphiphilic dopant, 3‐pentadecyl phenol 4‐sulphonic acid

Novel self‐assembled nano/microstructured conducting PANICN was prepared by in situ intercalative emulsion polymerization of aniline in aqueous dispersion of clay using bifunctional amphiphilic dopant, 3‐pentadecyl phenol‐4‐sulphonic acid (PDPSA) derivable from renewable resource. X‐ray diffraction and scanning electron microscopy (SEM) studies revealed the formation of monolayer of protonated PANI intercalated nanoclays with template polymerized self‐assembled micro/nanostructured protonated PANI. Nano/micro structured PANIs were formed by the supra molecular self‐assembling of the inter‐chain hydrogen bonding, inter‐plane phenyl stacking and electrostatic layer by layer self‐assembling (ELBS) between polarized alkyl chains present dopant anions and were manifested using fourier transform infra red spectroscopy and differential scanning calorimetry. On the basis of the results, structure‐directing effect of ‘anilinium salt micelle’ was schematically illustrated in this article. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2664–2673, 2007     

Synthesis and Characterization of New 3‐(3‐Hydroxyphenyl)‐4‐ alkyl‐3,4‐dihydrobenzo[e][1,3]oxazepine‐1,5‐dione Compounds

A series of 3‐(3‐hydroxyphenyl)‐4‐alkyl‐3,4‐dihydrobenzo[e][1,3]oxazepine‐1,5‐dione compounds with general formula C_nH_2n+1CNO(CO)₂C₆H₄(C₆H₄OH) in which n are even parity numbers from 2 to 18. The structure determinations on these compounds were performed by FT‐IR spectroscopy which indicated that the terminal alkyl chain attached to the oxazepine ring was fully extended. Conformational analysis in DMSO at ambient temperature was carried out for the first time via high resolution ¹H NMR and ¹³C NMR spectroscopy.     

Association of hydrophobically α,ω‐end‐capped poly(2‐methyl‐2‐oxazoline) in water

The α,ω‐end‐capped poly(2‐methyl‐2‐oxazoline) (C_n‐POXZ‐C_n) have been synthesized by a one‐pot process using cationic ring‐opening polymerization with an appropriate initiator and terminating agent. The polymers bearing different alkyl groups C₁₂ and C₁₈ have molecular weight in the range of 2.4 × 10³ to 14 × 10³ with a small polydispersity index. The solution behavior of the free chains has been analyzed in a nonselective solvent, dichloromethane, by small‐angle neutron scattering and dynamic light scattering. These amphiphilic polymers associate in water to form flower‐like micellar structures. Critical micelle concentrations, investigated by fluorescence technique, are in the range of 0.03–0.5 g L^?1 and are dependent on the hydrophilic/lipophilic balance. The structural properties of the aggregates have also been investigated by viscometry. Intrinsic viscosities of these polymers are in the same range as that of the precursors poly(2‐methyl‐2‐oxazoline) (POXZ) and mono‐functionalized polymers. Large viscosity increase corresponding to intermicellar bridging was observed in the vicinity of the micelle overlap concentration. Addition of hydroxypropyl β‐cyclodextrin (HβCD) has dissociated the aggregates and the intrinsic viscosities of the HβCD‐end‐capped chains have become comparable with the ones of POXZ precursor chains. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2477–2485, 2010     

Synthesis of well‐defined,soluble poly(3‐alkyl‐4‐benzamide) by chain‐growth condensation polymerization

Well‐defined poly(3‐alkyl‐4‐benzamide) was synthesized by means of chain‐growth condensation polymerization of phenyl 3‐octyl‐4‐(4‐octyloxybenzyl(OOB)amino)benzoate ( 1c ) from initiator 2 , followed by removal of the OOB groups on amide nitrogen of poly 1c . Polymerization of 1c with phenyl 4‐(trifluoromethyl)benzoate ( 2b ) in the presence of 1,1,1,3,3,3‐hexamethyldisilazide (LiHMDS) and LiCl in THF at ?10 °C gave poly 1c with a narrow molecular weight distribution (M_w/M_n ≤ 1.08) and a well‐defined molecular weight (M_n = 4480–12,700) determined by the feed ratio of monomer to initiator (from 10 to 30). The OOB groups of poly 1c were removed with H₂SO₄ to give the corresponding N‐unsubstituted poly(p‐benzamide) (poly 1c′ ) with low polydispersity. The solublity of poly 1c′ in polar organic solvents was dramatically higher than that of poly(p‐benzamide), demonstrating that introduction of an alkyl group on the aromatic ring is very effective for improving the solubility of poly(p‐benzamide). © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 360–365     

Studies on the modification of poly(ω‐bromoalkyl‐1‐glycidylether)s with 4′‐methoxybiphenyl‐4‐oxy mesogenic groups

A series of poly[ω‐(4′‐methoxy‐biphenyl‐4‐oxy)alkyl‐1‐glycidylether]s were synthesized by chemically modifying the corresponding poly(ω‐bromoalkyl‐1‐glycidylether)s with the sodium salt of 4‐hydroxy‐4′‐methoxybiphenyl. New high‐molecular‐weight side‐chain liquid‐crystalline polymers were obtained with excellent yields and almost quantitative degrees of modification. They were all insoluble in THF and other common solvents. Characterization by ¹³C NMR confirmed that all the polymers had the expected structure. The liquid crystalline behavior of the polymers was analyzed by DSC and polarized optical microscopy, and mesophase assignments were confirmed by X‐ray diffraction studies. Polymers that had alkyl spacers with n = 2 and 4 were smectic C, those that had spacers with n = 6 and 8 were nematic cybotactic, and those that had longer spacers (n = 10 and 12) were smectic C again. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5998–6006, 2005     

DC conductivity and spectroscopic characterization of binary dopant (ZrO2/AgI)‐doped polyaniline

Binary dopant mixture of (ZrO₂/AgI) (v/v) is prepared in different ratios to enhance the conductivity of the synthesized PANI. DC conductivity of (ZrO₂/AgI) (v/v) doped PANI samples is measured in the temperature range (300‐400K). The calculated values of pre‐exponential factor (σ₀) indicates that conduction is taking place through hopping process due to localized states present near the Fermi level. Structural changes due to interaction of dopant species with PANI are studied through FT‐IR and Photoluminescence characterization. Photoluminescence (PL) spectra of the doped samples occurred in the form of peaks and the intensities of these peaks vary according to the concentration of dopant mixture. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2682–2687, 2007     

Synthesis of some poly(4‐alkyl‐4‐azaheptamethylene‐D‐glucaramides)

Six 4‐alkyl‐4‐azaheptane‐1,7‐diamines, characterized as their solid bis(D ‐gluconamides), were prepared in a two‐step synthesis: bis(cyanoethylation) of the primary alkylamines (C₈–C₁₈, even‐numbered) followed by an efficient lithium aluminum hydride reduction of the resulting bisnitriles. The azadiamines were then used as monomers in condensation polymerizations with methyl D ‐glucarate 1,4‐lactone in a methanol solution, yielding polyhydroxypolyaminopolyamides isolated directly as white solids with varying hydrophobic/hydrophilic character. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3892–3899, 2000     

Luminescent Amphiphilic 2,6‐Bis(1‐alkylpyrazol‐3‐yl)pyridyl Platinum(II) Complexes: Synthesis,Characterization, Electrochemical,Photophysical, and Langmuir–Blodgett Film Formation Studies

Two series of novel platinum(II) 2,6‐bis(1‐alkylpyrazol‐3‐yl)pyridyl (N5Cn) complexes, [Pt(N5Cn)Cl][X] ( 1 – 9 ) and [Pt(N5Cn)(C?CR)][X] ( 10 – 13 ) (X=trifluoromethanesulfonate (OTf) or PF₆; R=C₆H₅, C₆H₄‐p‐CF₃ and C₆H₄‐p‐N(C₆H₅)₂), with various chain lengths of the alkyl groups on the nitrogen atom of the pyrazolyl units have been successfully synthesized and characterized. Their electrochemical and photophysical properties have been studied. Some of their molecular structures have also been determined by X‐ray crystallography. Two amphiphilic platinum(II) 2,6‐bis(1‐tetradecylpyrazol‐3‐yl)pyridyl (N5C14) complexes, [Pt(N5C14)Cl]PF₆ ( 7 ) and [Pt(N5C14)(C?CC₆H₅)]PF₆ ( 13 ), were found to form stable and reproducible Langmuir–Blodgett (LB) films at the air–water interface. The characterization of such LB films has been investigated by the study of their surface pressure–area (π–A) isotherms, UV/Vis spectroscopy, XRD, X‐ray photoelectron spectroscopy (XPS), FTIR, and polarized IR spectroscopy. The luminescence property of 13 in LB films has also been studied.     

Alkyl side chain length dependent compatibility of poly(4‐n‐alkylstyrene)s and 1,4‐rich polyisoprene blends

We investigated the compatibility of blends of 1,4‐rich polyisoprene (1,4‐PI) and poly(4‐n‐alkylstyrene)s with six kinds of n‐alkyl side groups, that is, methyl, ethyl, propyl, butyl, hexyl, and octyl focusing on carbon number of alkyl groups. Poly(4‐methylstyrene)/1,4‐PI blend was turned out to be immiscible at all temperature range adopted in this work and poly(4‐ethylstyrene)/1,4‐PI blend revealed UCST type phase behavior, while the others were found to be compatible. The phase diagrams of poly(4‐ethylstyrene)/1,4‐PI blends were obtained by optical microscopy, and the temperature dependence of the Flory‐Huggins interaction parameter χ has been estimated to be χ = ?0.036 + 24/T by applying lattice theory, where T is the absolute temperature. From this relationship χ value at room temperature (298 K) was calculated to be 0.045, the value is reasonably low for miscible polymers system. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55 , 1791–1797     

Synthesis and nonlinear properties of poly[1,4‐bis(4‐alkylpyridinium)butadiyne triflate]

1,4‐Bis(4‐alkylpyridinium)butadiyne triflate ( 2a and 2b ) that was prepared by the reaction of 1,4‐bis(4‐pyridyl)butadiyne ( 1 ) with alkyl trifluoro‐methanesulfonate, was found to grow into a large crystal as a result of the quaternized structure. The thermal treatment of 2a and 2b gave rise to 1,4‐addition polymerization to yield the polydiacetylene. The third‐order nonlinear optical susceptibility [χ⁽³⁾] of the polymer was determined by the femto‐second Z‐scan method to exhibit the remarkable high value of 1.1 × 10^?11 esu at 650 nm. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3686–3691, 2001     

Synthesis and characterization of polyaniline nanoparticles in phosphonic acid amphiphile aqueous micellar solutions for waterborne corrosion protection coatings

Polyaniline (PANI) dispersions consisting of 270 to 380 nm sized particles were prepared by oxidation with ammonium peroxydisulfate (APS) in n‐decylphosphonic acid (DPA) micellar solutions. The green dispersions do not undergo macroscopic precipitation for more than a year. The synthesized DPA doped PANI exhibited enhanced electrical conductivity (3.6 S cm^?1 ) compared with DPA‐PANI (2.3 x 10 ^{? 4} S cm ^{? 1}) prepared by postsynthesis treatment of the PANI‐base with DPA. It was shown that through protonation with decylphosphonic acid, polyaniline showed a significantly enhanced solubility in common organic solvents like chloroform, xylene, etc. The synthesized PANI was characterized by intrinsic viscosity, solubility, FT‐IR , conductivity, SEM , and TGA measurements. The wide‐angle X ‐ray diffraction study revealed the appearance of a peak located at low angles (d = 29.4 – 35.3 Å) suggesting the formation of layered structure of PANI backbone separated by long alkyl side chains of DPA. The anticorrosive performance of the bilayer coatings composed of a bottom layer of DPA doped polyaniline covered with a polyvinyl butyral topcoat, have been demonstrated for steel exposed to neutral saline solutions. It was found that the inhibitive properties of DPA dopant provides further protection to the base metal through smart release when damage is produced on the surface of the coating. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1606–1616     

Synthesis,characterization, and morphology of p‐toluene sulfonic acid‐doped polyaniline: A material for humidity sensing application

Polyaniline (PANI) doped with p‐toluene sulfonic acid was synthesized by chemical polymerization method using (NH₄)₂S₂O₈ as an oxidizing agent. This is a single step polymerization process for the direct synthesis of the conducting emeraldine salt (ES) phase, without the need of doping, dedoping, and redoping of the polymer. Presence of a free carrier tail at higher wavelength, characteristic of extended coil conformation along with a sharp polaronic peak is observed in the UV–vis spectrum of doped PANI in m‐cresol solvent. FT‐IR studies show the characteristic peaks of ES phase along with a sharp peak at 1120 cm^?1 representing vibration band of the dopant ion. Clumps of small fibers resulting in a sponge‐like structure was observed under scanning electron microscope. Thermal studies revealed a three‐step decomposition pattern. Conductivity is found to increase with an increase in the temperature showing “thermal activation behavior.” Decrease in resistance with increasing humidity is observed in a broad range of humidity. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2161–2169, 2005     

In situ doping polymerization of polyaniline microtubules in the presence of β‐naphthalenesulfonic acid

Conducting microtubules of Polyaniline (PANI) were synthesized for the first time by the “in situ doping polymerization” method in the presence of β‐naphthal‐ enesulfonic acid (NSA) as dopant. Different doping methods, such as “immerse doping” and “grind doping,” and different synthetic conditions, such as molar ratio of aniline (An) to NSA (An/NSA), concentration of NSA in the polymerization media, reaction temperature, and time were investigated to understand the formation of microtubules. It was found that the PANI–NSA microtubules can be formed only by the “in situ doping polymerization” method, and the above synthetic conditions strongly affect the formation of the PANI–NSA microtubules, especially the molar ratio of An to NSA. An optimal condition was found under which tubules with 1–3 μm in diameter and 10–50 μm in length were obtained. The morphology of PANI–NSA tubules was proved by SEM and TEM, and their backbone structure was characterized by FTIR, UV‐VIS, XPS, and X‐ray diffraction. Results of these measurements showed that the molecular structures of the resulted PANI–NSA microtubules were identical to that of PANI–HCl synthesized by conventional method. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 151–157, 1999     

Synthesis and properties of monodisperse multi‐triarylamine‐substituted oligothiophenes and 4,7‐bis(2′‐oligothienyl)‐2,1,3‐benzothiadiazoles for organic solar cell applications

Two novel series of monodisperse multi‐triarylamine‐substituted oligothiophenes, G ₂ ‐ OT ( n )‐ G ₂ with thiophene unit (n) varying from 6 to 8, and 4,7‐bis(2′‐oligothienyl)‐2,1,3‐benzothiadiazoles G ₂ ‐ OT ( n ) BTD ‐ G ₂ (n = 2, 4, 6) have been synthesized by the Suzuki coupling reactions. With an elongation of alkyl‐substituted oligothiophene core or an incorporation of benzothiadiazole into the central core, the absorption and emission spectra of G ₂ ‐ OT ( n )‐ G ₂ and G ₂ ‐ OT ( n ) BTD ‐ G ₂ series red‐shift substantially with the optical gap reducing to 1.95 eV for G ₂ ‐ OT ( 6 ) BTD ‐ G ₂ . Alkyl‐substitution onto oligothiophene backbone not only improves the solubility of the highly extended dendrimers but also renders coplanarity of the dendritic oligothiophene backbone at the excited state, which results in the enhancement of fluorescence quantum efficiency. The bulk heterojunction solar cells using these newly synthesized dendritic oligothiophenes as a donor material and [6,6]‐phenyl C₆₁‐butyric acid methyl ester (PCBM) as an acceptor material were fabricated and investigated which showed an increase in device performance as compared with those of the lower homologues. On increasing the loading of PCBM from 1.5 to 3 times in the active layer, there was also an enhancement in device performance with power conversion efficiencies of as‐fabricated solar cells increasing from 0.18% to 0.32%. In addition, proper annealing procedure could significantly improve the device performance of the dendrimer‐based photovoltaic cell. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 137–148, 2009     

Microemulsion polymerization of styrene stabilized by sodium dodecyl sulfate and short‐chain alcohols

Styrene microemulsion polymerizations with different short‐chain alcohols [n‐C_iH_2i+1OH (C_iOH), where i = 4, 5, or 6] as the cosurfactant were investigated. Sodium dodecyl sulfate and sodium persulfate (SPS) were used as the surfactant and initiator, respectively. The desorption of free radicals out of latex particles played an important role in the polymerization kinetics. An Arrhenius expression for the radical desorption rate coefficient was obtained from the polymerizations at temperatures of 50–70 °C. The polymerization kinetics were not very sensitive to the alkyl chain length of alcohols compared with the temperature effect. The maximal polymerization rate in decreasing order was C₆OH > C₄OH > C₅OH. This was related to the differences in the water solubility of C_iOH and the structure of the oil–water interface. The feasibility of using a water‐insoluble dye to study the particle nucleation mechanisms was also evaluated. The parameters chosen for the study of the particle nucleation mechanisms include the cosurfactant type (C_iOH), the SPS concentration, and the initiator type (oil‐soluble 2,2′‐azobisisobutyronitrile versus water‐soluble SPS). © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3199–3210, 2001     

Synthesis,characterization, and in vitro degradation of thermotropic polyesters and copolyesters based on terephthalic acid, 3‐(4‐hydroxyphenyl)propionic acid,and glycols

A new series of thermotropic liquid‐crystalline (LC) polyesters were prepared from a diacyl chloride derivative of 4,4′‐(terephthaloyldioxy)‐di‐4‐phenylpropionic acid (PTP) and glycols with a different number of methylene groups (n) [HO(CH₂)_n OH, n = 6–10, 12] by high‐temperature solution polycondensation in diphenyl oxide. PTP6/10 and PTP6/hydroquinone (H) LC copolyesters were also prepared according to a similar procedure. The chemical structure, LC, phase‐transition behaviors, thermal stability, and solubility were characterized by elemental analysis, Fourier transform infrared spectroscopy, ¹H and ¹³C NMR spectra, differential scanning calorimetry (DSC), thermogravimetric analysis, and a polarizing light microscope. The melting and isotropization temperatures decreased in a zigzag manner as the number of n increased. All of the polyesters formed a nematic phase with the exception of PTP8. The temperature ranges of the mesophase (ΔT) were much wider for the polyesters with an odd number of n's than those with an even number. ΔT increased markedly for the PTP6/10 and PTP6/H copolyesters. The in vitro degradations of the polymers were ascertained by enzymatic hydrolysis and alkaline hydrolysis. The model compound, PTP dihexylester, was synthesized and found to be degraded into terephthalic acid, 3‐(4‐hydroxyphenyl)propionic acid, and 1‐hexanol by Rhizopus delemar lipase, but PTPn homopolyesters and PTP6/10 and PTP6/H copolyesters were resistant to Rhizopus delemar hydrolysis. They were degradable in a sodium hydroxide buffer solution of pH 12 at 60 °C, depending on the number of n's and the copolymer composition. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3043–3051, 2001     

Amphiphilic conetworks. II. Novel two‐step synthesis of poly[2‐(dimethylamino)ethyl methacrylate]–polyisobutylene,poly(N‐isopropylacrylamide)–polyisobutylene,and poly(N,N‐dimethylacrylamide)–polyisobutylene hydrogels

Amphiphilic polymer conetworks consisting of hydrophilic poly[2‐(dimethylamino)ethyl methacrylate], poly(N‐isopropylacrylamide), or poly(N,N‐dimethylacrylamide) and hydrophobic polyisobutylene chains were synthesized with a novel two‐step procedure. In the first step, a methacrylate‐multifunctional polyisobutylene crosslinker was prepared by the cationic copolymerization of isobutylene with 3‐isopropenyl‐α,α‐dimethylbenzyl isocyanate. In the second step, the methacrylate‐multifunctional polyisobutylene crosslinker, with a number‐average molecular weight of 8200 and an average functionality of approximately 4 per chain, was copolymerized radically with 2‐(dimethylamino)ethyl methacrylate, N‐isopropylacrylamide, or N,N‐dimethylacrylamide into transparent amphiphilic conetworks containing 42–47 mol % hydrophilic monomer. The synthesized conetworks were characterized with solid‐state ¹³C NMR spectroscopy and differential scanning calorimetry. The amphiphilic nature of the conetworks was proved by swelling in both water and n‐heptane. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6378–6384, 2006     

Durable and refreshable polymeric N‐halamine biocides containing 3‐(4′‐vinylbenzyl)‐5,5‐dimethylhydantoin

A novel vinyl‐hydantoin monomer, 3‐(4′‐vinylbenzyl)‐5,5‐dimethylhydantoin, was synthesized in a good yield and was fully characterized with Fourier transform infrared (FTIR) and ¹H NMR spectra. Its homopolymer and copolymers with several common acrylic and vinyl monomers, such as vinyl acetate, acrylonitrile, and methyl methacrylate, were readily prepared under mild conditions. The polymers were characterized with FTIR and ¹H NMR, and their thermal properties were analyzed with differential scanning calorimetry studies. The halogenated products of the corresponding copolymers exhibited potent antibacterial properties against Escherichia coli, and the antibacterial properties were durable and regenerable. The structure–property relationships of the polymers were further discussed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3348–3355, 2001     

Synthesis and characterization of mesogen‐jacketed liquid‐crystal polymers based on 2,5‐bis(4′‐alkoxyphenyl)styrene

A series of novel mesogen‐jacketed liquid‐crystal polymers, poly[2,5‐bis(4′‐alkoxyphenyl)‐styrene] (P‐n, n = 1–11), were prepared via free‐radical polymerization of newly synthesized monomers, 2,5‐bis(4′‐alkoxyphenyl)styrene (M‐n, n = 1–11). The influence of the alkoxy tail length on the liquid‐crystalline behaviors of the monomers and the polymers was investigated with differential scanning calorimetry (DSC), thermogravimetry, polarized optical microscopy (POM), and wide‐angle X‐ray diffraction (WAXD). The monomers with n = 1–4, 9, and 11 were monotropic nematic liquid crystals. All other monomers exhibited enantiotropic nematic properties. Their melting points (T_m's) decreased first as n increased to 6, after which T_m increased slightly at longer spacer lengths. The isotropic–nematic transition temperatures decreased regularly with increasing n values in an odd–even way. The glass‐transition temperatures (T_g's) of the polymers first decreased as the tail lengths increased and then leveled off when n ≥ 7. All polymers were thermally stable and entered the mesophase at a temperature above T_g. Upon further heating, no mesophase‐to‐isotropic melt transition was observed before the polymers decomposed. WAXD studies indicated that an irreversible order–order transition for the polymers with short tails (n ≤ 5) and a reversible order–order transition for those with elongated tails (n ≥ 6) occurred at a temperature much higher than T_g. However, such a transition could not be identified by POM and could be detected by DSC only on heating scans for the polymers with long tails (n ≥ 7). © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1454–1464, 2003