Synthesis and characterization of aromatic polyesters with dicyanovinyl substituents

The synthesis, characterization, and structure—property relations of aromatic polyesters with dicyanovinyl substituents is presented. Two comparable series of polyesters based on 3,4-dihydroxybenzylidenemalononitrile and 3,4-dihydroxy-5-methoxybenzylidenemalononitrile were prepared. As aromatic diacid components, terephthalic acid, phenylterephthalic acid, isophthalic acid, and 2-phenylisophthalic acid were used. The polyesters were prepared by solution polycondensation. GPC investigations revealed the existence of substantial amounts of defined cyclic products. These cycles could be isolated by preparative GPC. The polyesters are soluble in common low boiling organic solvents, particularly the phenyl-substituted ones. The polyesters are amorphous and have glass transition temperatures between 140 and 170°C. The absorption maxima are in the 306–322 nm range. The cut-off wavelength is between 400 and 428 nm. The polyesters with methoxy substitutent have generally the absorptions at longer wavelength. The refractive index of thin films of these polyesters were between 1.61 and 1.63 at 632.8 nm. © 1993 John Wiley & Sons, Inc.     

Synthesis and characterization of polyesters derived from polychlorinated aromatic diacids

New, thermally stable polyesters with varying chlorine content were prepared by solution and interfacial polycondensation between chlorinated aromatic dichlorides (perchloroterephthaloyl dichloride, 2,5-dichloroterephthaloyl dichloride, and perchloro-4,4′-dichloroformyl biphenyl with different aliphatic and aromatic diols). The polymers were characterized by infrared spectroscopy, elemental analysis, differential scanning calorimetry, and thermogravimetric analysis. Their solubilities and molecular weights were also determined. The influence of chlorine content on the thermal properties of the polymers is discussed.     

Synthesis and characterization of new aromatic polyesters containing cardo decahydronaphthalene groups

Three cardo bisphenols containing decahydronaphthalene group viz., 4,4′-(octahydro-2(1H)-naphthylidene)bisphenol, 4,4′-(octahydro-2(1H)-naphthylidene)bis-3-methylphenol and 4,4′-(octahydro-2(1H)-naphthylidene)bis-3,5-dimethylphenol were synthesized starting from commercially available 2-naphthol and were utilized for synthesis of new aromatic polyesters by phase transfer-catalyzed interfacial polycondensation with isophthaloyl chloride, terephthaloyl chloride and a mixture of isophthaloyl chloride and terephthaloyl chloride (50:50 mol %). Inherent viscosities and number average molecular weights (M_n) of polyesters were in the range 0.35-0.84 dL/g and 13,300-48,500 (Gel Permeation Chromatography, polystyrene standard), respectively. Polyesters were readily soluble in organic solvents such as dichloromethane, chloroform, tetrahydrofuran, meta-cresol, pyridine, N,N-dimethylformamide, N,N-dimethylacetamide, and 1-methyl-2-pyrrolidinone at room temperature and could be cast into tough, transparent and flexible films from their chloroform solutions. Wide-angle X-ray diffraction measurements revealed the amorphous nature of polyesters. The glass transition temperature of polyesters was in the range 207-287 °C. The temperature at 10% weight loss (T₁₀), determined from thermogravimetric analysis of polyesters, was in the range 425-460 °C indicating their good thermal stability.     

Synthesis and characterization of polyesters derived from aromatic 1,4-dimethoxylated diacids

Polyesters were synthesized from the dichlorides of 2,5-dimethoxyterephthalic and 2,5-dimethoxy-1,4-benzenediacetic with dialcohols. The polymers were characterized by elemental analysis and infrared (IR) spectroscopy. Their intrinsic viscosity, glass transition temperature, and thermal decomposition were determined.     

Synthesis and characterization of new aromatic liquid crystalline polyesters having phenyl substituents

Two different series of new aromatic liquid crystalline (LC) polyesters were prepared from 3-phenyl-4, 4'-biphenyldicarboxylic acid (PBDA) and 1-phenyl-2, 6-naphthalenedicarboxylic acid (PNDA). PBDA and PNDA were polymerized with various aromatic diols such as hydroquinone, substituted hydroquinones, isomeric naphthalenediols and 4, 4'-biphenol, and the resulting polyesters were characterized by DSC, WAXD, and on a cross-polarizing microscope for the study of their thermal transition and crystallization properties, and mesophases formed therefrom.     

Synthesis and characterization of wholly aromatic polyesters derived from 1-phenyl-2,6-naphthalene-dicarboxylic acid and aromatic diols

A series of new wholly aromatic polyesters was synthesized by melt polycondensation of 1-phenyl-2,6-naphthalenedicarboxylic acid (PNDA) and diacetates of various aromatic diols. The aromatic diols studied are hydroquinone (HQ), methylhydroquinone (MHQ), phenylhydroquinone (PHQ), (α-phenylisopropyl)hydroquinone (PIHQ), 2,6-naphthalenediol (2,6-ND), 1,4-naphthalenediol (1,4-ND), and 4,4′-biphenol (BP). These polyesters were characterized for their crystallinity, glass transition temperature (T_g), melting temperature (T_m), liquid crystallinity, and thermal stability. In general, crystallinity of the polyesters are very low and the T_g values of the polyesters range from 150 to 172°C depending on the structure of aromatic diols. All of the polymers formed nematic phases above their T_m or T_g. The polyesters derived from PHQ and PIHQ are soluble in chlorinated hydrocarbon solvents. The initial decomposition temperatures of the polyesters are above 400°C under N₂ atmosphere. © 1996 John Wiley & Sons, Inc.     

Synthesis and characterization of soluble aromatic polyesters derived from substituted terphenyl and quinquephenyl diols

Rigid aromatic polyesters containing alkoxy or phenyl-substituted oligophenyls were prepared. Soluble polymers were obtained also in cases where phenyl-substituted quinquephenyl diols were combined with asymmetric phenyl-substituted terephthalic acid. The synthesized polyesters were characterized by viscosimetry, gel permeation chromatography, thermal analysis, and dynamic mechanical analysis. The temperature dependence of the intrinsic viscosity was sensitive to the type of side groups. Thermogravimetry has shown that polyesters with aromatic substituents were stable up to 380–400°C. The glass transition temperatures of the polyesters with aromatic side groups were in the 220–260°C range as determined by DSC. Polyesters with hexyloxy side chains show crystallinity. Dynamic mechanical analysis showed that in the cases where aromatic substituents were used to increase solubility, the obtained polymers have very useful mechanical properties at high temperatures. The polymer having the quinquephenyl unit in the main chain has an almost constant modulus up to 340°C. © 1996 John Wiley & Sons, Inc.     

Synthesis and mesomorphic behaviour of some aromatic polyesters

Six new aromatic polyesters were synthesized by the phase-transfer catalytic polycondensation. The polymers obtained were characterized by infra-red, X-ray diffraction, D.S.C., depolarized light intensity and polarizing microscope. Poly(p,p'-hydroquinone-1,4-phenylene dioxyacetate) and poly(p,p'-hydroquinone-1,4,7-trioxaheptamethylene dibenzoate) were found to be thermotropic liquid crystals but related polyesters are not. The results are discussed on the basis of the thermodynamic data obtained.     

Synthesis and mesomorphic behaviour of some aromatic polyesters

Abstract

Six new aromatic polyesters were synthesized by the phase-transfer catalytic polycondensation. The polymers obtained were characterized by infra-red, X-ray diffraction, D.S.C., depolarized light intensity and polarizing microscope. Poly(p,p'-hydroquinone-1,4-phenylene dioxyacetate) and poly(p,p'-hydroquinone-1,4,7-trioxaheptamethylene dibenzoate) were found to be thermotropic liquid crystals but related polyesters are not. The results are discussed on the basis of the thermodynamic data obtained.     

Synthesis,thermal and radiation sensitivities of halogen-containing decamethylene-spacered aromatic polyesters

A series of halogen-containing aromatic polyesters with decamethylene-spacer groups was synthesized by the solution polymerization from 4,4′-dicarboxyl-1,10-diphenoxy-decane and bisphenol A. Incorporation of fluorine atoms in the bisphenol A units in the polymer backbone enhanced the solubility of the polyesters in various organic solvents, as did the substitution of chlorine and bromine on the aromatic rings of the bisphenol A, ortho to the ester linkages. The effect of the halogen substituents on the thermal and radiation sensitivities of the polyesters has been investigated. The inherent viscosities of THF solutions at 30°C ranged from 0.25 to 0.63 dL/g. The number average (6,000∼31,000) and weight average molecular weights (12,000∼48,000) were measured by gel permeation chromatogrpahy, resulting in polydispersity indices of M₂/M_n=1.6∼2.0. The chemical structures of the polyesters were characterized by means of IR spectroscopy, ¹H NMR and ¹³C NMR spectroscopies and elemental analyses. All the results were in good agreement with the expected formula. Comparison of ¹³C NMR spectra of the polymers aided in the assignments of the structures. Only the unsubstituted polyester derived from bisphenol A was found to be semicrystalline by X-ray diffraction and DSC measurements, with a crystalline melting temperature of 160°C. The glass transition temperatures of the polyesters was found to be dependent on the size of the halogen substituent on the repeating units, and ranged from 77 to 140°C. The thermal stabilities of the polyesters showed a dependence on the nature of the halogen substituent, as did the high energy radiation sensitivites of the polymers, as assessed by the yields of radicals at 77 K. © 1998 John Wiley & Sons, Ltd.     

New thermally stable polyesters based on 2,5-pyridinedicarbonyl dichloride and aromatic diols:Synthesis and characterization

Six new thermally stable polyesters(4a-f) were synthesized through the solution polycondensation reaction of 2,5-pyridine dicarbonyldichloride(2) with six aromatic diols in N,N'-dimethyl acetamide(DMAc) solution and in the presence of pyridine as a base.The polycondensation reactions produce a series of new polyesters(4a-f) in high yields,and inherent viscosity between 0.30 and 0.55 dL/g.The resulting polyesters were characterized by elemental analysis,viscosity measurements,thermal gravimetric analysis(...     

Synthesis and characterization of new cardo polyesters

New phthalide-containing bisphenols, phenolphthalein-N-(3-methylanilide) (3-PMA), and phenolphthalein-N-(4-methylanilide) (4-PMA), were synthesized from phenolphthalein and m- and p-toluidines. These bisphenols were polycondensed with terephthaloyl chloride (TPC) using an interfacial or solution polymerization technique to yield new polyesters. Copolymers were also obtained by utilizing different molar proportion of phenolphthalein (PPH) and 3-PMA or 4-PMA with TPC. The polymers prepared by solution polymerization were obtained in 93–99% yields and showed reduced viscosities in the range 0.37–0.83 dL/g. They were readily soluble in chlorinated hydrocarbons and aprotic polar solvents. The polyesters showed glass transition temperatures in the range 261–300°C as measured by DSC. Thermogravimetric analysis of the polyesters indicated no weight loss below 408°C under N₂ atmosphere. Structure–property correlations among these cardo polyesters have been discussed. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3227–3234, 1997     

Synthesis of reactive aromatic polyesters having pendant chlorohydrin moieties

A monomer containing a chlorohydrin moiety, propyl chlorohydrin diphenolate (PCHDP), was synthesized. Reactive polyesters having these pendant chlorohydrin moieties were prepared by the interfacial polycondensation of isophthaloyl chloride with PCHDP or with PCHDP and diphenolic acid using phase transfer catalyst. The molar ratio of reactants and the phase ratio of water to organic solvent strongly affect the molecular weight of resulting polymers and polymers with high molecular weight are obtained at the molar ratio of 1.0–1.15 and the phase ratio of 2.0–3.5. Swelling of the growing polymers is dependent on the molar ratio of the reactants and the phase ratio because of the hydrophilic and hydrophobic nature of the pendant chlorhydrin moiety. The resulting polymers are not soluble in any solvent except water in which hydrolysis occurs. Thus so, the structure of polymers was confirmed by ¹³C CP/MAS NMR. © 1996 John Wiley & Sons, Inc.     

Synthesis of hydrolytically degradable aromatic polyesters with lactide moieties

A synthetic route to higher molecular weight processable polyesters with bisphenol A terephthalate/isophthalate moieties and lactide moieties which are of potential interest for tissue engineering is described. The combination of aliphatic and aromatic moieties is a promising concept for processable polyesters with potential sites for physiological degradation and improved mechanical properties. The molecular structure of the copolyesters prepared by melt condensation via an acid chloride route and incorporation of the lactide moieties by transesterification of an oligo dl -lactide was confirmed by infrared, ¹H and ¹³C nuclear magnetic resonance spectroscopy as well as gel permeation chromatography. The thermal and mechanical properties of copolyesters with different amounts of lactide moieties are reported and correlated with their composition. The reaction mechanism by transesterification was proved by a model reaction with a physical blend of the components and the hydrolytical behavior of the copolyesters under physiological conditions has been investigated. © 1997 John Wiley & Sons, Ltd.     

Synthesis, characterization and biodegradable studies of 1,3-propanediol based polyesters

A series of biodegradable polyesters were synthesized from dicarboxylic acids and 1,3-propanediol catalyzed by transestrification polycondensation reaction in the bulk. The structure, average molecular weights and physical properties of the resulting aliphatic polyesters were characterized by ¹H NMR, FT-IR, solution viscosity, GPC, DSC and TGA. Homopolyesters show higher degree of crystallinity, melting and thermal stability in comparison to copolyesters. The biodegradability of the polyesters was determined by monitoring the normalized weight loss of polyester films with time in phosphate buffer (pH 7.2) without and with Rhizopus delemar lipase at 37 °C. The rate of enzymatic degradation of homopolyesters follows the path PPSu > PPAd > PPSe. PPSe did not show significant weight loss in presence of enzyme which may be due to its highest degree of crystallinity and melting point compared to the PPSu, PPAd and copolyesters. In the soil burial degradation polyester sample showed severe surface degradation by the attack of microorganism.     

Synthesis, characterization, degradation of biodegradable castor oil based polyesters

A new family of castor oil based biodegradable polyesters was synthesized by catalyst free melt condensation reaction between two different diacids and castor oil with d-mannitol. The polymers synthesized were characterized by NMR spectroscopy, FT-IR and the thermal properties were analysed by DSC. The results of DSC show that the polymer is rubbery in physiological conditions. The contact angle measurement and hydration test results indicate that the surface of the polymer is hydrophilic. The mechanical properties, evaluated in the tensile mode, shows that the polymer has characteristics of a soft material. In vitro degradation of polymer in PBS solution carried out at physiological conditions indicates that the degradation goes to completion within 21 days and it was also found that the rate of degradation can be tuned by varying the curing conditions.     

Synthesis and characterization of hyperbranched polyesters and polyurethane coatings

Polyurethane (PU) coatings are widely used for variety of high‐performance applications in today's coating technology. The emerging hyperbranched polymers having three‐dimensional morphology have opened a new avenue to tailor the architecture of PU coatings. The methodology followed here is based on preparation of PU coatings from hyperbranched polyester. Initially, different hyperbranched polyester polyols (HPs) were synthesized by varying the hydroxyl‐terminated precursors that is, pentaerythritol, trimethylol propane or glycerol and keeping the diacid that is, adipic acid quantity constant at various mole ratios of 1:0.6, 1:0.8, 1:0.9, and 1:1, respectively. The obtained HPs were characterized by nuclear magnetic resonance (NMR) spectroscopy, matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF)‐mass spectrometry, and Fourier transform‐infrared (FTIR) spectroscopy. The degree of branching and the quantity of different structural units present in the various HPs were calculated by integrating the quaternary carbon and carbonyl zone in ¹³C NMR spectroscopy. The extent of condensation in different HPs was also calculated from ¹H NMR spectra. Later on, NCO‐terminated PU prepolymers (NCO‐PU) were synthesized by reacting HPs with isophorone diisocyanate (IPDI) at NCO/OH ratio of 1.6:1. In the third step, the excess NCO content in the NCO‐capped PU prepolymers were reacted with atmospheric moisture and hyperbranched polyurethane (HPU) coatings were formed. The coating films were analyzed by FTIR and dynamic mechanical thermal analysis instruments. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2673–2688, 2007     

Synthesis of aromatic polyesters by direct polycondensation with triphenylphosphine dichloride

Aromatic polyesters of high molecular weights were prepared by the direct polycondensation reaction of dicarboxylic acids and bisphenols or hydroxybenzoic acids with triphenylphosphine dichloride as a new condensing agent. Reaction conditions, including the amount of reagents and the concentration of monomer, solvent, and acid acceptor, were investigated. The aromatic polyester with the solution viscosity of 1.66 dL/g was obtained from bisphenol. A and terephthalic and isophthalic acid in quantitative yield under the optimum condition. The principal advantage of this condensing agent is that, based on the recycling system, recovered triphenylphosphine oxide can be reconverted to the reactive triphenylphosphine dichloride by treating with phosgene or oxalyl chloride.     

Synthesis and characterization of polyesters containing heterocyclic thiaxanthone units

Several polyesters containing thiaxanthone rings were prepared from 2,7-dichloroformylthiaxanthone-5,5′-dioxide ( IVa ), 2,8-dichloroformylthiaxanthone-5,5′-dioxide ( IVb ), and bisphenols by solution polycondensation. The 2,8-diethoxycarbonylthiaxanthone-5,5′-dioxide ( V ) was prepared and characterized by spectral methods to confirm the formation of 2,8-thiaxanthonedicarboxylic acid-5,5′-dioxide ( IVb ). Prior to polymer synthesis two model compounds,2,7-diphenoxycarbonylthiaxanthone-5,5′-dioxide (MDE-1) and 2,8-diphenoxycarbonylthiaxanthone-5,5′-dioxide (MDE-2), were synthesized and characterized by spectral methods. The polyesters were obtained in 62–78% yield and had inherent viscosities in the range 0.42–0.90 dL/g. The effect of thiaxanthone rings on solubility, crystallinity, and thermal stability of the polyesters are also discussed. The polyesters have decomposition temperatures in the range 372–438°C.