Phase behavior and photo‐responsive studies of photoactive liquid crystalline hyperbranched polyethers containing benzylidene moiety

Two sets of hyperbranched polyether epoxies were synthesized to study the effect of substituent, rigidity, and nature of photoactive unit on the thermal and photoresponsive properties. Each set was comprised of one molecule with an acyclic moiety in the repeating unit, and two molecules with a cyclic moiety of varying rigidity (cycle size) in the repeating unit. Two substituents on aromatic rings in the repeating unit were present in one set, and other set was without a substituent. The mesogenic and photoresponsive properties were studied and correlated to the varied structural parameters. The effects of varied molecular structural parameters on phase behavior and photoresponsive properties were very prominent. Out of six monomeric diols, only four have exhibited liquid crystalline phase while the polymers corresponding to all monomeric diols revealed mesophase. The findings in photoresponsive properties were further supported by molecular modeling studies. The changes in refractive index, photoviscosity, and fluorescence intensity with irradiation time substantiated the spectral pattern observed in UV‐Vis spectroscopy. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2774–2786, 2009     

Molecular engineering of photoactive liquid crystalline polyester epoxies containing benzylidene moiety

A series of photoactive liquid crystalline polyester epoxies incorporating bisbenzylidene segments as photoactive mesogenic cores were synthesized by polyaddition of diepoxy monomers and terephthalic acid/trimesic acid. To investigate the influence of structural parameters such as, molecular architecture, structural rigidity of mesogenic unit and substituents on thermal, mesogenic, and photoactive properties, the bisbenzylidene segment was incorporated into one acyclic and two cycloalkanone units with two and four substituents, respectively in both linear and hyperbranched architectures. Degree of branching of hyperbranched polymers was found to be in the range of 0.49–0.62. All polymers exhibited nematic mesophase (nematic droplets). Photo induced (2π + 2π) cycloaddition reaction, upon exposure to light at 365 nm, was examined. Inter molecular photocycloaddition was confirmed by photoviscosity measurement of UV irradiated polymer solutions. Faster photo induced reactivity of polymers in hyperbranched architecture was observed when compared to linear structure. Acyclic units facilitated photocycloaddition, and five‐membered ring showed higher photoactivity compared to six‐membered ring. The steric hindrance caused by substituents decreased the photoactivity of polymers. Refractive index change was found to be in the range of 0.015–0.024. Substantial variation of refractive index indicates that these polymers could be used for optical recording. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7637–7655, 2008     

Effect of molecular architecture and size of mesogen on phase behavior and photoactive properties of photoactive liquid crystalline hyperbranched polyester epoxies containing benzylidene moiety

A series of photoactive liquid crystalline linear and hyperbranched polyester epoxies were synthesized by polyaddition of photoactive bis benzylidene alkanone diol monomers and terephthalic acid and trimesic acid respectively with good yield. The effect of molecular architecture (linear and hyperbranched), size of mesogenic unit (cyclic and acyclic units) on the physicochemical, thermal, mesogenic, and photoactive properties of hyperbranched polymers were studied and compared. Degree of branching of hyperbranched polymers was found to be in the range of 0.46–0.49. Monomers containing cyclic moieties only exhibited nematic mesophase, while all polymers exhibited typical nematic mesophase. Intermolecular photo cycloaddition reaction was studied by ultraviolet–visible spectra (UV–vis) and NMR spectroscopy and photo viscosity measurement of UV irradiated polymer solutions. Faster photo induced behavior of hyperbranched polymers containing acyclic alkanone moiety, as compared to polymers containing cycloalkanone moieties, was observed. The change in the refractive index was found to be in the range of 0.02–0.024. Substantial variation of refractive index indicates that this polymer could be used for optical recording. All the polymers were also found to be fluorescent in nature. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 552–563, 2008     

Synthesis,photochemical and phase behavior of linear and hyperbranched photoactive benzylidene liquid‐crystalline polyesters

Photoactive hyperbranched benzylidene liquid‐crystalline polyester (PAHBP) and photoactive linear benzylidene liquid‐crystalline polyester (PALBP) were synthesized by solution polycondensation with pyridine as an acid acceptor. PAHBP and PALBP were thoroughly characterized with Fourier transform infrared, ¹H and ¹³C NMR, ultraviolet–visible spectrophotometry, fluorescent spectrophotometry, gel permeation chromatography, thermogravimetric analysis, differential scanning calorimetry, and polarized optical microscopy. Both polymers exhibited nematic mesophase. The glass‐transition temperature and liquid‐crystalline isotropic temperature of PAHBP were higher than those of PALBP. During photolysis under ultraviolet light, both polymers underwent an intermolecular photocycloaddition reaction, and the photoactivity of PAHBP was faster than that of PALBP; this was further confirmed by photoviscosity studies. PALBP and PAHBP were fluorescent in nature. An increase in the fluorescence intensity with the time of ultraviolet‐light irradiation was observed for both PAHBP and PALBP. The rate of increase in the fluorescence intensity of the linear analogue (PALBP) was higher than that of the hyperbranched polymer (PAHBP). This behavior could be attributed to the attainment of better planarity in the case of the linear one but not in the case of PAHBP because of the rapid crosslinking of PAHBP leading to an irregular architecture. This behavior was further confirmed by the calculation of the steric energy from corresponding model compounds. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3986–3994, 2006     

Tailoring the liquid crystalline property via controlling the generation of dendronized polymers containing azobenzene mesogen

The first‐ and second‐generation dendronized polymers containing azobenzene mesogen were designed and successfully synthesized via free radical polymerization. The chemical structures of the monomers were confirmed by elemental analysis, ¹H NMR, and ¹³C NMR. The molecular characterizations of the polymers were performed with ¹H NMR and gel permeation chromatography. The phase structures and transition behaviors were studied using differential scanning calorimetry, polarized light microscopy, and small‐angle X‐ray scatter experiments. The experiment results revealed that the first‐generation dendronized polymer exhibited liquid crystalline behavior of the conventional side‐chain liquid crystalline polymer with azobenzene mesogen, that is, the polymer exhibited smectic phase structure at lower temperature and nematic phase structure at higher temperature. However, the second‐generation dendronized polymers exhibited more versatile intriguing liquid crystalline structures, namely smectic phase structure at lower temperature and columnar nematic phase structure at higher temperature, and moreover, the phase structure still remained before the decomposition temperature. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1149–1159, 2010     

Synthesis and phase behaviors of side‐chain liquid‐crystalline polymers containing azobenzene mesogen with the different length alkyl tail

A series of side‐chain liquid‐crystal polymers, poly[6‐[4‐(4′‐n‐alkyl benzoateazo)phenoxy]‐hexylmethacrylate]s (PMAzoCOOR_m, m = 1, 2, 3, 4, 5, 6, 8, 10, 14, and 18) have been prepared by two synthetic methods. The chemical structure of the monomers was confirmed by ¹H NMR and mass spectrometry. The molecular characterizations of the polymers were performed with ¹H NMR and gel permeation chromatograph. The phase behaviors of polymers were investigated by the combination of techniques including differential scanning calorimetry, polarized optical microscopy, and small‐angle X‐ray scattering. For m = 1, 2, 3, 4, 5, and 6, the polymers exhibited a monosmectic A phase in which the smectic layer period was almost identical to the side‐chain length. In addition, for m = 2, 3, 4, and 5, they presented the monosmectic C phase in low temperature; moreover, the tilt angle increased from 23.3 to 40.5°. For m = 8, 10, 14, and 18, the polymers showed a bilayer smectic A phase in which the layer spacing was larger than a fully extended side chain but less than two extended chains. On the other hand, for the clearing point, with the increasing of m, it first decreased, and then increased. All of these indicated that the length of alkyl tails played an important role in the phase behaviors of these polymers. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2759–2768     

Synthesis and properties of mesogen‐jacketed liquid crystalline polymers containing bistolane mesogen

On the basis of the concept of mesogen‐jacketed liquid crystalline polymers, a series of new methacrylate monomers, (2,5‐bis[2‐(4′‐alkoxyphenyl) ethynyl] benzyl methacrylate (MACn, n = 4, 6, 8, 10, and 12) and 2,5‐bis[2‐(6′‐decanoxynaphthyl) ethynyl] benzyl methacrylate (MANC10), and their polymers, PMACn (n = 4, 6, 8, 10, and 12) and PMANC10 were synthesized. The bistolane mesogen with large π‐electron conjugation were side‐attached to the polymer backbone via short linkages. Various characterization techniques such as differential scanning calorimetry, wide‐angle X‐ray diffraction, and polarized light microscopy were used to study their mesomorphic phase behavior. The polymer PMACn with shorter flexible substituents (n = 4) forms the columnar nematic (?_N) phase, but other polymers with longer flexible tails (n = 6, 8, 10, and 12) can develop into a smetic A (S_A) phase instead of a ?_N phase. The PMANC10 containing naphthyl can also form a well‐defined S_A phase. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

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     

Structure–property studies and orientation effects of polythiophenes containing mesogenic side chains

Liquid crystalline materials display unique properties, which can be exploited in organic light emitting diodes. Polythiophene model compounds containing phenyl groups linked with azomethine, ester, and alkoxy groups [thiophene‐3‐alkyloxy benzoyloxy aniline series (N series) and thiophene‐3‐alkoxy phenoxy amino benzoate series (R Series)] were synthesized. Molecular orbital calculations were performed and the predicted band gaps compared to understand the effects of spacer length and linkage. The experimental photoabsorption characteristics are compared with the theoretically predicted band gap. Photoabsorption and emission studies on N series and R series polymers as the function of polarizer angle suggest that polymers of both series emit polarized light in all base color ranges. The electroemission characteristics of the above‐synthesized polymers were also recorded as the function of polarizer angle. The results show that the compounds also emit polarized electroemission, and the EL polarization ratio decreases with the increase of alkoxy chain length for N and R polymers. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1463–1477, 2008     

Photoactive liquid crystalline polymers: A comprehensive study of linear and hyperbranched polymers synthesized by A2B2, A2B3, A3B2, and A3B3 approaches

A series of linear and hyperbranched polyester epoxies, with varied structural parameters such as kinked structure and different dendritic architectures, were synthesized by A₂ + B₂, A₂ + B₃, A₃ + B₂, and A₃ + B₃ approaches. The structures of synthesized monomers and polymers were confirmed by Fourier transform infrared, ¹H NMR, and ¹³C NMR spectroscopic techniques. The effect of varied structural parameters on phase behavior and photoresponsive properties was investigated by using differential scanning calorimeter, thermal optical polarized microscope, UV–visible spectroscopy, photoviscosity, and refractive index studies. The transition temperatures of hyperbranched polymers were higher than that of the corresponding linear analogues. All the polymers showed nematic phase (nematic droplets) over a broad temperature range. The effect of kinked structural unit on photoresponsive property is less in both linear and hyperbranched architectures. Although the effect of architectural nature is highly considerable within the hyperbranched architectures, the polymer (HPE–33) synthesized by A₃ + B₃ approach showed highest rate of photocrosslinking, followed by HPE–I 32; HPE–T 32, and HPE–23, which were synthesized by A₃ + B₂ and A₂ + B₃ approaches, respectively. The findings in photoresponsive properties were further supported by molecular modeling studies. Substantial variation of refractive index (0.015–0.024) indicates that these polymers could be used for optical recording. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis and properties of novel phosphorus‐containing thermotropic liquid crystalline copoly(ester imide)s

A series of novel phosphorus‐containing polyesterimides were prepared from diols—a mixture of a new aromatic phosphorus‐containing bisphenol, namely 1,4‐bis[N‐(4‐hydroxyphenyl)phthalimidyl‐5‐carboxylate]‐2‐(6‐oxido‐6H‐dibenz<c,e><1,2>oxaphosphorin‐6‐yl)‐naphtalene, with aliphatic diols such as 1,3‐propanediol, 1,4‐butanediol, 1,5‐pentanediol, 1,6‐hexanediol, and 1,12‐dodecanediol—and an aromatic diacid chloride containing two preformed ester groups, namely terephthaloyl‐bis‐(4‐oxibenzoyl‐chloride), via high‐temperature polycondensation in o‐dichlorobenzene. The structures of monomers and polymers were verified by means of Fourier transform infrared (FTIR) spectroscopy and ¹H NMR spectroscopy. The molar ratio of aromatic bisphenol to aliphatic diol was varied to generate a series of copolyesterimides with tailored physicochemical properties, structure–properties relationships being established. The effect of the phosphorus content on the thermal properties and the flame retardancy was evaluated by means of thermogravimetric analysis (TGA), TGA–FTIR, and scanning electron microscopy. The polymers were stable up to 340 °C showing a 5% weight loss in the range of 340–395 °C and a 10% weight loss in the range of 370–415 °C. The char yields at 700 °C were in the range of 13.6–38% increasing with the content of phosphorus‐containing bisphenol. The effect of the aliphatic content on the liquid crystalline behavior was investigated by polarized light microscopy, differential scanning calorimetry, and X‐ray diffraction. The transition temperatures from crystal to liquid crystalline melt were in the range of 209–308 °C. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Vinyl‐terminated side‐chain liquid‐crystalline polyethers containing mesogenic benzylideneaniline moieties

The synthesis of two vinyl‐terminated side‐chain liquid‐crystalline polyethers containing benzylideneaniline moieties as mesogenic cores was approached in two different ways: by chemically modifying poly(epichlorohydrin) with suitable mesogenic acids or by polymerizing analogous glycidyl ester or glycidyl ether derivatives. In all the conditions tested, the first approach led to materials in which the imine group was hydrolyzed. The second approach led to the desired polymers PG2a and PG2b , but only from the glycidyl ether derivatives and when the initiator was the system that combined polyiminophosphazene base t‐Bu‐P₄ and 3,5‐di‐t‐butylphenol. These polymers were chemically characterized by IR and ¹H and ¹³C NMR spectroscopies. The estimated degrees of polymerization ranged from 30 to 36. The liquid crystalline behavior of the synthesized polymers was studied by differential scanning calorimetry, polarized optical microscopy (POM) and X‐ray diffraction. Both polymers behave like liquid crystals and exhibited a single mesophase, which was recognized as a smectic C mesophase, probably with a bilayer arrangement, i.e., a smectic C₂ mesophase. The crosslinking of both polymers was performed with dicumyl peroxide as initiator, which led to liquid crystalline thermosets. POM and X‐ray diffraction confirmed that the mesophase organization mantained on the crosslinked materials. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1877–1889, 2006     

Synthesis and properties of mesogen‐jacketed liquid crystalline polymers containing biphenyl mesogen with asymmetric substitutions

This work focuses on the design, synthesis, and characterization of a series of mesogen‐jacketed liquid crystalline polymers (MJLCPs), poly(alkyl 4′‐(octyloxy)‐2‐vinylbiphenyl‐4‐carboxylate) (pVBP(m,8), m = 1, 2, 4, 6, 8, 10, 12). For the first time, we realized asymmetric substitutions in the mesogens of MJLCPs. The polymers obtained by conventional free radical polymerization were investigated in detail by a combination of various techniques, such as differential scanning calorimetry, wide‐angle X‐ray diffraction, and polarized light microscopy. Our results showed that all the polymers were thermally stable, and their glass transition temperatures decreased when m increased. The liquid crystalline (LC) phases that developed at high temperatures and disappeared at low temperatures were strongly dependent on the difference in lengths of alkyl groups on the 4 and 4′ substitution positions of the side‐chain biphenyl. While polymer pVBP(1,8) was not liquid crystalline, columnar liquid crystalline phases were observed for all other pVBP(m,8) (m = 2, 4, 6, 8, 10, 12) polymers. Polymer pVBP(8,8) showed a tetragonal columnar nematic liquid crystalline phase, and the other LC polymers exhibited columnar nematic phases. In additions, the smaller the difference in the lengths of the terminal alkyls, the easier the development of the liquid crystalline phase. Birefringence measurements showed that solution‐cast polymer films exhibited moderately high positive birefringence values, indicating potential applications as optical compensation films for liquid crystal displays. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Novel photo-crosslinkable liquid crystalline polymers containing vanillylidene cycloalkanones and azobenzene units

Two series of novel liquid crystalline photo-crosslinkable bis(vanillylidene-azobenzene) cycloalkanone containing polymers, namely poly(vanillylidene alkyloxy-4,4'-azobenzenedicarboxylic ester)s, have been synthesised from bis[m-hydroxyalkyloxy(vanillylidene)cycloalkanone] (m = 6, 8, 10) with azobenzene dicarbonylchloride by solution polycondensation method at ambient temperature. Polymers with varying spacer lengths have been synthesised and characterised by spectroscopic techniques. These variations have been correlated with the thermal properties and transition temperatures. Thermal transitions were analysed by differential scanning calorimetry (DSC) and the mesophases were identified by hot stage optical polarised microscopy (HOPM). All of the polymers were found to exhibit liquid crystalline properties. Transition temperatures were observed to decrease with increasing spacer length. The thermogravimetric analysis reveals that all of the polymers were stable up to 280°C undergo two-stage decomposition. Using the UV-visible photolysis studies we investigated the simultaneous behaviour of reactivity rates of crosslinking in the vanillylidene unit and isomerisation caused by the azobenzene unit in the photo-crosslinkable main chain liquid crystalline polymers. The photolysis of liquid crystalline bis(vanillylidene)cycloalkanone-based polymers reveals that there are two kinds of photoreactions in these systems: the EZ photoisomerisation of azobenzene unit and 2p+2p addition by vanillylidene units. The EZ photoisomerisation in the liquid crystal phase disrupts the parallel stacking of the mesogens, resulting in the transition from the liquid crystal phase to isotropic phase. The photoreaction involving 2p+2p addition of the bis(vanillylidene)cycloalkanone units in the polymers results in the conjoining of the chains. The cyclopentanone polymers exhibited a faster rate of photolysis than the cyclohexanone polymers.     

Ordered nanostructures at two different length scales mediated by temperature: A triphenylene‐containing mesogen‐jacketed liquid crystalline polymer with a long spacer

A mesogen‐jacketed liquid crystalline polymer (MJLCP) containing triphenylene (Tp) moieties in the side chains with 12 methylene units as spacers (denoted as PP12V) was synthesized. Its liquid crystalline (LC) phase behavior was studied with a combination of solution ¹H NMR, solid‐state NMR, gel permeation chromatography, thermogravimetric analysis, polarized light microscopy, differential scanning calorimetry, and one‐ and two‐dimensional wide‐angle X‐ray diffraction. By simply varying the temperature, two ordered nanostructures at sub‐10‐nm length scales originating from two LC building blocks were obtained in one polymer. The low‐temperature phase of the polymer is a hexagonal columnar phase (Φ_H, a = 2.06 nm) self‐organized by Tp discotic mesogens. The high‐temperature phase is a nematic columnar phase with a larger dimension (a′ = 4.07 nm) developed by the rod‐like supramolecular mesogen—the MJLCP chain as a whole. A re‐entrant isotropic phase is found in the medium temperature range. Partially homeotropic alignment of the polymer can be achieved when treated with an electric field, with the polymer in the Φ_H phase developed by the Tp moieties. The incorporation of Tp moieties through relatively long spacers (12 methylene units) disrupts the ordered packing of the MJLCP at low temperatures, which is the first case for main‐chain/side‐chain combined LC polymers with MJLCPs as the main‐chain LC building block to the best of our knowledge. The relationship of the molecular structure and the novel phase behavior of PP12V has implications in the design of LC polymers containing nanobuilding blocks toward constructing ordered nanostructures at different length scales. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 295–304     

Synthesis and phase behavior of side‐chain liquid‐crystalline polymers containing malachite green lactone groups

New side‐chain liquid‐crystalline polymers containing both cholesteric and thermochromic side groups were synthesized. Their chemical structures were confirmed with elemental analyses and Fourier transform infrared, proton nuclear magnetic resonance, and carbon‐13 nuclear magnetic resonance spectra. The mesogenic properties and phase behavior were investigated with differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy, and X‐ray diffraction measurements. The effect of the concentration of dye side groups on the phase behavior of the polymers was examined. The polymers showed smectic or cholesteric phases. Those polymers containing less than 20 mol % dye groups had good solubility, reversible phase transitions, wider mesophase temperature ranges, and higher thermal stability. The experimental results demonstrated that the isotropization temperature and mesophase temperature ranges decreased with an increasing concentration of dye groups. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3870–3878, 2004     

Synthesis and characterization of thermotropic liquid crystalline polyurethanes from 4,4′‐bis(6‐hydroxyhexoxy) biphenyl and aliphatic diols

A series of thermotropic liquid crystalline polyurethanes (LCPUs) were synthesized by the polyaddition reactions of 2,4‐toluene diisocyanate (2,4‐TDI) with 4,4′‐bis(6‐hydroxyhexoxy)biphenyl (BHHBP) and aliphatic diol. The intrinsic viscosities of the polymers were measured by Ubbelohde viscometer, and the chemical structure was confirmed by Fourier transform infrared spectroscopy (FT‐IR). The LCPUs were examined by differential scanning calorimetry (DSC), polarized optical microscopy (POM), wide angle X‐ray diffraction (WAXD), and thermogravimetric analysis (TGA). The intrinsic viscosities were 0.56–0.83 dl/g. According to the melting point (T_m) and the isotropic temperature (T_i) of the LCPUs, the temperature range of the liquid crystalline phase became wider with increased number of methylene spacers in the polyurethane. The LCPUs exhibited a nematic phase with a threaded texture and had a wide mesophase temperature range. The decomposition temperature of the LCPUs was >300°C. On WAXD, the LCPUs give a dispersing peak at 2θ ≈ 20°, and a strong diffraction peak at 2θ ≈ 25°. Copyright © 2008 John Wiley & Sons, Ltd.     

Hydrogen‐bonded thermotropic liquid‐crystalline polyester–amides from bis(hydroxy alkamido)aranes: Synthesis and properties

Hydrogen‐bonded aromatic–aliphatic polyester–amides (PEAs) were prepared by solution/melt polycondensation of aromatic–aliphatic amidodiols 1,4‐bis(4‐hydroxybutyramide)benzene (BHBB), 1,4‐bis(5‐hydroxy pentamide)benzene, 1,4‐bis(6‐hydroxyhexamide)benzene, 1,4‐bis(4‐hydroxybutyramidexylene), 1,4‐bis(5‐hydroxypentamidexylene, 1,4‐bis(4‐hydroxybutyramide)benzene, and 1,4‐bis(6‐hydroxyhexamidexylene) with terephthaloyl chloride/dimethyl terephthalate. Aromatic–aliphatic amido diols were prepared by the aminolysis of γ‐butyrolactone, δ‐valerolactone, and ?‐caprolactone with aromatic diamines such as paraphenylene diamine and paraxylene diamine. The monomers and polymers were characterized by chemical analysis (hydroxyl value and elemental analysis), Fourier transform infrared spectroscopy, ¹H NMR, and ¹³C NMR. The thermal‐ and phase‐transition behaviors of the polymers were investigated by differential scanning calorimetry in combination with hot‐stage optical microscopy. Crystallinity of polymers was examined with wide‐angle X‐ray diffraction. The polymers exhibited liquid crystallinity with layered structures formed by self‐organization of the hetero intermolecular hydrogen‐bonded networks indicating smectic phases except for PEAs prepared from BHBB. The hydrogen atom of the phenyl‐substituent group forces the neighboring carbonyl groups out of plane of the rings preventing formation of layered structures in the case of BHBB. The PEAs retained intermolecular hydrogen bonding even in the mesomorphic state, and variations in the hydrogen‐bonded lamellae/micelles might be responsible for the variations from one smectic to another texture. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 335–346, 2003