Direct polycondensation of N‐trimellitylimido‐L‐isoleucine with aromatic diamines

N‐Trimellitylimido‐L ‐isoleucine (3) was prepared from the reaction of trimellitic anhydride with L ‐isoleucine [L ‐2‐amino‐3‐methylvalerianic acid or (2S,3S)‐2‐amino‐3‐methyl‐n‐valerinic acid] in an N,N‐dimethylformamide solution at the refluxing temperature. The direct polycondensation reaction of the monomer imide diacid (3) with 1,4‐phenylenediamine, 4,4′‐diaminodiphenylmethane, 4,4′‐diaminodiphenylsulfone, diaminodiphenylether, 1,5‐naphthalendiamine, 2,4‐diaminotoluene, and 1,3‐phenylenediamine was performed in a medium consisting of triphenyl phosphite, N‐methyl‐2‐pyrolidone (NMP), pyridine, and calcium chloride. The polycondensation was performed under two different conditions: in one method, the reaction mixture was heated in an NMP solution at 60, 90, and then 130°C for different periods of time, and in the other method, the reaction mixture was refluxed only for 1 min in the same solvent. The resulting poly(amide imide)s (PAIs), with inherent viscosities of 0.21–0.37 dL/g, were obtained in high yields. All of these compounds were fully characterized by IR spectra, elemental analyses, and specific rotation measurements. Some structural characterizations and physical properties of these new optically active PAIs were examined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 116–122, 2003     

Synthesis and characterization of new polyureas based on 4‐(4′‐aminophenyl)urazole and various diisocyanates

4‐(4′‐Aminophenyl)urazole (AmPU) was prepared from 4‐nitrobenzoic acid in six steps. The reaction of monomer AmPU with n‐isopropylisocyanate was performed in N,N‐dimethylacetamide solutions at different ratios, and the resulting disubstituted and trisubstituted urea derivatives were obtained in high yields and were finally used as models for polymerization reactions. The step‐growth polymerization reactions of AmPU with hexamethylene diisocyanate, isophorone diisocyanate, and toluene‐2,4‐diisocyanate were performed in N‐methylpyrrolidone solutions in the presence of pyridine as a catalyst. The resulting novel polyureas had inherent viscosities of 0.11–0.18 dL/g in dimethylformamide at 25°C. These polyureas were characterized with IR, ¹H‐NMR, elemental analysis, and thermogravimetric analysis. Some physical properties and structural characterization of these novel polyureas are reported. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2692–2700, 2003     

Microwave‐assisted rapid polycondensation reaction of 4‐(4′‐acetamidophenyl)‐1,2,4‐triazolidine‐3,5‐dione with diisocyanates

4‐(4′‐Aminophenyl)‐1,2,4‐triazolidine‐3,5‐dione was reacted with 1 mol of acetyl chloride in dry N,N‐dimethylacetamide (DMAc) at ?15°C and 4‐(4′‐acetamidophenyl)‐1,2,4‐triazolidine‐3,5‐dione [4‐(4′‐acetanilido)‐1,2,4‐triazolidine‐3,5‐dione] (APTD) was obtained in high yield. The reaction of the APTD monomer with excess n‐isopropylisocyanate was performed at room temperature in DMAc solution. The resulting bis‐urea derivative was obtained in high yield and was finally used as a model for the polymerization reaction. The step‐growth polymerization reactions of monomer APTD with hexamethylene diisocyanate, isophorone diisocyanate, and tolylene‐2,4‐diisocyanate were performed under microwave irradiation and solution polymerization in the presence of pyridine, triethylamine, or dibutyltin dilaurate as a catalyst. Polycondensation proceeded rapidly, compared with conventional solution polycondensation; it was almost completed within 8 min. The resulting novel polyureas had an inherent viscosity in the range of 0.07–0.17 dL/g in dimethylformamide or sulfuric acid at 25°C. These polyureas were characterized by IR, ¹H‐NMR, elemental analysis, and thermogravimetric analysis. The physical properties and structural characterization of these novel polyureas are reported. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2103–2113, 2004     

Microwave‐assisted and classical heating polycondensation reaction of bis(p‐amido benzoic acid)‐N‐trimellitylimido‐L‐leucine with diisocyanates as a new method for preparation of optically active poly(amide imide)s

A new class of optically active poly(amide imide)s were synthesized via direct polycondensation reaction of diisocyanates with a chiral diacid monomer. The step‐growth polymerization reactions of monomer bis(p‐amido benzoic acid)‐N‐trimellitylimido‐L‐leucine (BPABTL) (5) as a diacid monomer with 4,4′‐methylene bis(4‐phenylisocyanate) (MDI) (6) was performed under microwave irradiation, solution polymerization under gradual heating and reflux condition in the presence of pyridine (Py), dibuthyltin dilurate (DBTDL), and triethylamine (TEA) as a catalyst and without a catalyst, respectively. The optimized polymerization conditions according to solvent and catalyst for each method were performed with tolylene‐2,4‐diisocyanate (TDI) (7), hexamethylene diisocyanate (HDI) (8), and isophorone diisocyanate (IPDI) (9) to produce optically active poly(amide imide)s by the diisocyanate route. The resulting polymers have inherent viscosities in the range of 0.09–1.10 dL/g. These polymers are optically active, thermally stable, and soluble in amide type solvents. All of the above polymers were fully characterized by IR spectroscopy, ¹H NMR spectroscopy, elemental analyses, specific rotation, and thermal analyses methods. Some structural characterization and physical properties of this new optically active poly(amide imide)s are reported. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1647–1659, 2004     

Preparation and solid‐state polyamidation of hexamethylenediammonium adipate: The effect of sodium 5‐sulfoisophthalic acid

The effect of sodium 5‐sulfoisophthalic acid (NaSIPA) on the solid‐state polymerization of hexamethylenediammonium adipate was studied. In particular, different polyamide salt grades, such as a model salt of hexamethylenediamine and NaSIPA and a polyamide 6,6 salt containing NaSIPA, were prepared through alternative procedures based on the solution–precipitation technique. Furthermore, selected salt grades were solid‐state‐polymerized in a thermogravimetric analysis chamber under static and flowing nitrogen. Critical reaction parameters, such as the reaction temperature, surrounding gas, and presence of NaSIPA, were investigated to determine the rate‐controlling mechanism of the process. More specifically, NaSIPA significantly influenced solid‐state polyamidation by reducing the reaction rate and changing the prevailing mechanism. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1609–1619, 2007     

Polycondensation reaction of N,N′‐(4,4′‐oxydiphthaloyl)‐bis‐L‐methionine diacid chloride with aromatic diamines: Synthesis and properties

Several new optically active poly(amide‐imide)s have been synthesized by solution polycondensation of readily available aromatic diamines with diacid chloride containing ether‐imide and L ‐methionine moieties. Three polycondensation techniques were used: low temperature solution polycondensation, short period reflux conditions, and microwave‐assisted polycondensation. In all cases, the reactions were carried out using equimolecular amounts of the two monomers, in polar aprotic solvents. The obtained compounds were characterized by elemental analysis, solubility tests, FTIR, and ¹H NMR spectrometry. Thermal stability of the polymer was studied by thermogravimetric analysis. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1038–1044, 2006     

A novel preparation method of polyaluminum chloride/polyacrylamide composite coagulant: Composition and characteristic

Inorganic/organic composite coagulants have drawn a wide attention through the years owing to its superior coagulation behaviors. In this study, polyaluminum chloride (PAC)/polyacrylamide (PAM) composite coagulant was synthesized by ultraviolet (UV) irradiation by using PAC and acrylamide (AM) as raw materials, urea as a solubilizer, and 2,2′‐Azobis[2‐(2‐imidazolin‐2‐yl)propane]dihydrochloride (VA‐044) as an initiator. The effect of total monomer mass fraction, solubilizer dosage and initiator dosage on the viscosity and molecular weight of PAC/PAM composite coagulant was discussed. The results suggest that the composite coagulant with high polymerization degree, intrinsic viscosity of 1483 mL/g and molecular weight of 7.38 million, could be obtained when the total monomer mass fraction of 40%, urea dosage of 1.5% and initiator dosage of 0.6% are chosen in the preparation. It is a potential preparation method of composite coagulant with short preparation time and high preparation efficiency. Fourier transform infrared spectrum and ¹H nuclear magnetic resonance spectroscopy represent that the coagulant for polyaluminum chloride and polypropylene are copolymer. Thermal gravimetric analysis describes the high thermal stability of composite coagulant. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44500.     

Polymerization of 4‐(4′‐N‐1,8‐naphthalimidophenyl)‐1,2,4‐triazolidine‐3,5‐dione with diisocyanates

4‐(4′‐Aminophenyl)‐1,2,4‐triazolidine‐3,5‐dione ( 1 ) was reacted with 1,8‐naphthalic anhydride ( 2 ) in a mixture of acetic acid and pyridine (3 : 2) under refluxing temperature and gave 4‐(4′‐N‐1,8‐naphthalimidophenyl)‐1,2,4‐triazolidine‐3,5‐dione ( NIPTD ) ( 3 ) in high yield and purity. The compound NIPTD was reacted with excess n‐propylisocyanate in N,N‐dimethylacetamide solution and gave 1‐(n‐propylamidocarbonyl)‐4‐[4′‐(1,8‐naphthalimidophenyl)]‐1,2,4‐triazolidine‐3,5‐dione ( 4 ) and 1,2‐bis(n‐propylamidocarbonyl)‐4‐[4′‐(1,8‐naphthalimidophenyl)]‐1,2,4‐ triazolidine‐3,5‐dione ( 5 ) as model compounds. Solution polycondensation reactions of monomer 3 with hexamethylene diisocyanate ( HMDI ), isophorone diisocyanate ( IPDI ), and tolylene‐2,4‐diisocyanate ( TDI ) were performed under microwave irradiation and conventional solution polymerization techniques in different solvents and in the presence of different catalysts, which led to the formation of novel aliphatic‐aromatic polyureas. The polycondensation proceeded rapidly, compared with conventional solution polycondensation, and was almost completed within 8 min. These novel polyureas have inherent viscosities in a range of 0.06–0.20 dL g^?1 in conc. H₂SO₄ or DMF at 25°C. Some structural characterization and physical properties of these novel polymers are reported. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2861–2869, 2003     

Synthesis and characterization of new polyamides derived from 4‐(4′‐aminophenyl)urazole and aliphatic diacid chlorides

4‐(4′‐Aminophenyl)urazole (AmPU) was prepared from 4‐nitrobenzoic acid in six steps. The reaction of AmPU with acetyl chloride was performed in N,N‐dimethylacetamide solutions at different ratios, and the resulting disubstituted and trisubstituted amide derivatives were obtained in high yields and were used as models for polymerization reactions. Polycondensation reactions of AmPU with succinyl chloride, suberoyl chloride, and sebacoyl chloride were performed with conventional solution polymerization techniques in the presence of different catalysts, such as pyridine, triethylamine, and dibutyltin dilaurate, and led to the formation of novel aliphatic polyamides. The resulting novel polyamides had inherent viscosities of 0.11–0.22 dL/g in dimethylformamide or H₂SO₄ at 25°C. These polyamides were characterized with IR, ¹H‐NMR, elemental analysis, and thermogravimetric analysis. Some physical properties and structural characterization of these novel polyamides are reported. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3173–3185, 2004     

Direct solid state polycondensation of tetra‐ and hexa‐methylenediammonium terephthalate: Scaling up from the TGA micro‐reactor to a laboratory autoclave

The direct solid state polycondensation (DSSP) reaction of tetramethylenediammonium and hexamethylenediammonium terephthalate (4 T and 6 T salts) in a laboratory scale autoclave reactor was investigated. The autoclave reactor is 3 orders of magnitude larger than the TGA micro‐reactor we used previously. The larger scale reactor allows more extensive analyses such as analysis of the formed condensate by titration and allows investigation of operating conditions that are important on industrial scale, such as batch (closed system) versus semibatch (open system) operation and flow of nitrogen used. Comparing the two scales has given important insight into the parameters that are important in scaling‐up direct solid‐state polycondensation. Furthermore, the effect of scaling up on the quality of the final semiaromatic polyamide products was determined, by comparing the obtained thermal properties, the solution viscosity and the end‐group concentrations obtained by ¹H‐NMR spectroscopy. When operating the open reactor with a gentle nitrogen stream, the results show that products of similar properties were obtained from the micro and the laboratory scale reactors if critical parameters like temperature and pressure time profile were kept the same. The solid character of the reacting mass was retained only when maintaining the reactor at atmospheric pressure, allowing the condensation water to be removed. When keeping the autoclave reactor closed, both polyamide (PA) products (i.e., PA4T and PA6T) were agglomerated as a result of a solid melt transition during the direct solid state polycondensation. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45080.     

Efficient combination of ionic liquids and microwave irradiation as a green protocol for polycondensation of 4-(3-hydroxynaphthalene)-1,2,4-triazolidine-3,5-dione with diisocyanates

In this investigation, a novel urazole containing 3-hydroxynaphthalene group, 4-(3-hydroxynaphthalene)-1,2,4-triazolidine-3,5-dione (3HNTD) was synthesized in six steps starting from 3-hydroxy-2-naphthalene carboxylic acid. The reaction of 3HNTD with n-propylisocyanate was performed in N,N-dimethylacetamide solution at different molar ratios, and the resulting monosubstituted as well as disubstituted urea derivatives were obtained in high yields and were used as model compounds for polymerization studies. An efficient, fast and easy method for the preparation of new soluble poly(urea-urethane)s (PUU)s containing heterocyclic and chromophoric moieties from 3HNTD and various diisocyanates are employed using room temperature ionic liquids and molten tetrabutylammonium bromide under microwave irradiation as well as conventional heating. The polymerization reactions occurred rapidly under microwave and produced a series of PUUs with good yields and moderate inherent viscosities of 0.21-0.46 dL/g. All of the new PUUs showed good solubility and were readily dissolved in organic solvents.     

Conversion of polyester into heat‐resistant polyamide by reacting with aromatic diamine compound II. Semibatch reaction by nitrogen gas sweeping process

The conversion of poly(ethylene terephthalate) (PET) into heat‐resistant polyamide was carried out in the solid state polycondensation by applying a nitrogen gas sweeping process. The reaction product obtained by the catalyzed and uncatalyzed batch reaction with the specified reaction condition was used as the starting material in the semibatch reaction process. Nitrogen gas was introduced into the reactor to remove a volatile reaction byproduct from the reaction mixture. Effect of the semibatch reaction variables such as temperature, time, and nitrogen gas sweeping rate on the extent of reaction and the heat‐resistant property of polyamide obtained was investigated. A comparison of the extent of reaction in the semibatch reaction process was made between the catalyzed starting material and the uncatalyzed one. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2223–2232, 2004     

Free‐radical copolymerization of [(4‐isopropyl phenyl) oxycarbonyl] methyl methacrylate with acrylonitrile and methyl methacrylate

The present investigation has been achieved in accordance with the Diels–Alder reaction (1,4 cycloaddition) to produce a new halogenated bicyclic adduct. ortho‐Bromoallylbenzoate is a new dienophile that was prepared in a pure form, and its structure was confirmed. The Diels–Alder syntheses of hexachlorocyclopentadiene and the new dienophile were studied to determine the optimum condensation reaction conditions under a temperature range of 90–160°C, reaction times of 1–8 h, and molar diene/dienophile ratios from 1:1 to 5:1 as a consequence. The optimum conditions reached were a temperature of 140°C, an initial diene/dienophile molar ratio of 3:1, and a duration time of 6 h. The maximum stoichometric yield under these optimum conditions (82.5%) was obtained. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2331–2338, 2003     

Anionic copolymerization of diglycidyl ether of bisphenol A with Meldrum's acid derivatives initiated by 4‐(N,N‐dimethylamino) pyridine

The anionic copolymerization of diglycidyl ether of bisphenol A with 2,2,5,5‐tetramethyl‐4,6‐dioxo‐1,3‐dioxane or 6,6‐dimethyl‐(4,8‐dioxaspiro[2.5]octane‐5,7‐dione) with 4‐(N,N‐dimethylamino) pyridine as an initiator to form thermosets was studied with differential scanning calorimetry, and the kinetics were evaluated with isoconversional procedures. The evolution during the curing process of the epoxide, lactone, and linear ester bands was evaluated with Fourier transform infrared spectroscopy in the attenuated total reflection mode to clarify the reactions taking place. The shrinkage during curing, thermomechanical properties, and thermal degradability of the materials obtained by copolymerization with the different derivatives of Meldrum's acid were evaluated and related to the chemical structure of the final network. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and characterization of new photoactive polyamides containing 4‐(4‐dimethylaminophenyl)urazole units

4‐(4‐dimethylaminophenyl)‐1,2,4‐triazolidine‐3,5‐dione ( DAPTD ) was prepared from 4‐dimethylaminobenzoic acid in five steps. The compound DAPTD was reacted with excess acetyl chloride in N,N‐dimethylacetamide (DMAc) solution and gave 1,2‐bisacetyl‐4‐[4‐(dimethylaminophenyl)]‐1,2,4‐triazolidine‐3,5‐dione as a model compound. Solution polycondensation reactions of monomer with succinyl chloride (SucC), suberoyl chloride (SubC), and sebacoyl chloride (SebC) were performed under conventional solution polymerization techniques in the presence of triethylamine and pyridine as a catalyst in N‐methylpyrrolidone (NMP) and led to the formation of novel aliphatic polyamides. These novel polyamides have inherent viscosities in the range of 0.09–0.21 dL/g in N,N‐dimethylformamide (DMF) at 25°C. Fluorimetric studies of the model compound as well as polymers were performed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 947–954, 2007     

Microwave‐promoted rapid synthesis of new optically active poly(amide imide)s derived from N,N′‐(pyromellitoyl)‐bis‐L‐isoleucine diacid chloride and aromatic diamines

A pyromellitic dianhydride (benzene‐1,2,4,5‐tetracarboxylic dianhydride) was reacted with L ‐isoleucine in acetic acid, and the resulting imide acid [N,N′‐(pyromellitoyl)‐bis‐L ‐isoleucine] (4) was obtained in a high yield. 4 was converted into N,N′‐(pyromellitoyl)‐bis‐L ‐isoleucine diacid chloride by a reaction with thionyl chloride. The polycondensation reaction of this diacid chloride with several aromatic diamines, including 1,4‐phenylenediamine, 4,4′‐diaminodiphenyl methane, 4,4′‐diaminodiphenylsulfone (4,4′‐sulfonyldianiline), 4,4′‐diaminodiphenylether, 2,4‐diaminotoluene, and 1,3‐phenylenediamine, was developed with two methods. The first method was polymerization under microwave irradiation, and the second method was low‐temperature solution polymerization, with trimethylsilyl chloride used as an activating agent for the diamines. The polymerization reactions proceeded quickly and produced a series of optically active poly(amide imide)s with good yields and moderate inherent viscosities of 0.17–0.25 dL/g. All of the aforementioned polymers were fully characterized by IR, elemental analyses, and specific rotation. Some structural characterization and physical properties of these optically active poly(amide imide)s are reported. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 951–959, 2004     

Synthesis,characterization, and thermal degradation kinetics of the copolymer poly(4‐methoxybenzyl methacrylate‐co‐isobornyl methacrylate)

A copolymer of 4‐methoxybenzyl methacrylate and isobornyl methacrylate was synthesized by atom transfer radical polymerization. The structure of poly(4‐methoxybenzyl methacrylate‐co‐isobornyl methacrylate) was confirmed by means of Fourier transform infrared, ¹H‐NMR, and ¹³C‐NMR techniques. The molecular weight distribution values of the copolymer were determined with gel permeation chromatography. The number‐average molecular weight and polydispersity index values of poly(4‐methoxybenzyl methacrylate‐co‐isobornyl methacrylate) were found to be 12,500 and 1.5, respectively. The kinetics of the thermal degradation of the copolymer was investigated with thermogravimetric analysis at different heating rates. The activation energy values obtained with the Kissinger, Flynn–Wall–Ozawa, and Tang methods were determined to be 166.38, 167.54, and 167.47 kJ/mol, respectively. Different integral and differential methods were used, and the results were compared with these values. Doyle approximation was also used for comparing the experimental results to master plots. An analysis of the experimental results suggested that the reaction mechanism was an R₁ deceleration type in the conversion range studied. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation of 2‐ethyl‐4‐methylimidazole derivatives as latent curing agents and their application in curing epoxy resin

Three kinds of 2‐ethyl‐4‐methylimidazole (EMI) derivatives (N‐acetyl EMI, N‐benzoyl EMI, and N‐benzenesulfonyl EMI) were synthesized through the reaction of EMI with acetyl chloride, benzoyl chloride, and benzenesulfonyl chloride, respectively. And the structure was confirmed by Fourier transform infrared spectroscopy (FTIR) and ¹H‐nuclear magnetic resonance spectroscopy (¹H NMR) spectra. Furthermore, the synthesized EMI derivatives were applied in diglycidyl ether of bisphenol A epoxy resin (DGEBA) as latent curing agent. Differential scanning calorimeter (DSC) was used to analyze the curing behavior of DGEBA/EMI derivative systems, indicating DGEBA could be efficiently cured by the EMI derivatives at 110～160°C, and the corresponding curing activation energy ranged from 71 to 86 kJ/mol. Viscosity data proves that the storage life of DGEBA with N‐acetyl EMI (NAEMI), N‐benzoyl EMI (NBEMI), and N‐benzenesulfonyl EMI (NBSEMI) at room temperature was 38 d, 50 d, and 80 d, and that at 10°C was 90 d, 115 d, and 170 d, respectively. Besides, thermogravimetry (TG), izod impact strength (IIS), and tensile shear strength (TSS) were tested to characterize the thermal stability and mechanical properties of DGEBA cured by EMI derivatives. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42563.     

Preparation and characterization of a foam regulator with ultra‐high molecular weight

Multistage emulsion polymerization was used to prepare ultra‐high molecular weight foam regulator of low cost, with methyl methacrylate (MMA), butyl acrylate (BA), styrene (St) as main raw materials. Ubbelohde viscometer, dynamic light scattering, infrared and raman spectra, TEM, DSC, TGA, and GPC were all used to characterize constituent and structure, morphology, and molecular weight. As a result, when the ratio of soft monomer (BA) and hard monomer (St + MMA) is 1:3, MMA:St = 4:1, potassium persulfate (KPS): 0.15%, sodium hydrogen sulfite (SHS): 0.05%, azodiisobutyronitrile (AIBN): 0.15%, divinyl benzene (DVB): 0.3%, the final product terpolymer has obvious core‐shell structure and ultra‐high molecular weight (M_w = 1,400,000). This kind of foam regulator showed improvements in the melt strength, prevention of bubble coalescence and reduction on cost when compared with the traditional. Finally, the coefficients of poly (methyl methacrylate‐butyl acrylate‐styrene) terpolymer's Mark‐Houwink equation were calculated with tetrahydrofuran (THF) solvent at 25 °C. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44479.     

Synthesis and characterization of cholesteric thermotropic liquid crystalline polyesters

Cholesteric liquid crystalline polyesters were successfully synthesized from isosorbide, methyl hydroquinone, and isophthaloyl chloride. Homo/copolyesters were synthesized by the solution polycondensation method, for which a mild organic base such as pyridine was employed. Inherent viscosities of polyesters P‐3–P‐5 were in the range of 0.31–0.39 dL/g at 25°C in chloroform, and polyesters P‐1 and P‐2 were insoluble in chloroform. Homo/copolyesters based on isosorbide, methyl hydroquinone, and isophthalic acid had thermal stability at more than 300°C on the basis of 10% weight loss. The thermotropic liquid crystalline properties were examined by differential scanning calorimetry and polarizing optical microscopy. Wide‐angle X‐ray diffraction study demonstrated that polyesters P‐1, P‐2, and P‐3 were semicrystalline, whereas the degree of crystallinity of polyesters P‐4 and P‐5 was less than 5%. Copolyester P‐4 showed formation of a yellow iridescent streak at 209°C on heating and development of a Grandjean texture at 270°C on heating. These are typical textures of the cholesteric liquid crystalline phase. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1232–1237, 2007