Weight Loss Temperatures In Nitrogen Research Articles

Facile synthesis and characterization of soluble aramid containing polar hydroxyl side group

A series of aramids containing hydroxyl side group (NOM-OHc, where c is the molar fraction of hydroxyl substitution in the polymer, and c = 0, 10, 20, 40, 60, 80, 100) were synthesized by direct high-temperature polycondensation. The synthesis employed a facile process. The monomer, 4,4'-(terephthaloylbis(azanediyl))bis(2-hydroxybenzoic acid), was prepared simply via an esterification reaction. The chemical structures of the soluble aramids were confirmed by 1H NMR. And the molecular weight and mass dispersity of the aramids were obtained by size exclusion chromatography, instead of the traditional intrinsic viscosity method. The use of unsymmetrical monomers and the introduction of hydroxyl side group into the aramid structure decrease the conjugation of the polymer main chain, and thus the resulting aramid has excellent solubility in relatively polar solvents, such as N-methy-2-pyrrolidone, dimethylsulfoxide, N,N-dimethylacetamide, and N,N-dimethylformamide. As a result, the molding processability of the aramids and their composites is greatly improved. For example, films can be made by solution spinning and casting. The films have good mechanical strength, with tensile strength, tensile modulus, and elongation at break in the range of 68–95 MPa, 2.65–3.12 GPa, and 5–10%. The thermal resistance of the aramids is still quite good, with 5% weight loss temperatures in nitrogen and in air in the range of 360–430 °C.

Structure-property relationship of low dielectric constant polyimide fibers containing fluorine groups

A series of copolyimide (co-PI) fibers with low dielectric constants and excellent comprehensive properties have been successfully prepared via a two-step wet-spinning method by incorporating 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (TFMB) into rigid polymer backbones of 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA)/p-phenylenediamine (p-PDA). The dielectric constant of PI fibers were substantially reduced from 3.0 to 2.48 at the frequency of 10 GHz after the introduction of trifluoromethyl (-CF3) groups. Meanwhile, the prepared PI fibers exhibited high thermal stability as well as excellent mechanical properties. The co-PI fibers possessed the optimum tensile strength of 1.4 GPa and modulus of 83.3 GPa at the p-PDA/TFMB molar ratio of 7/3. The 5% weight loss temperature in nitrogen ranged from 523 to 558 °C, and the glass transition temperature decreased from 372 °C to 295 °C with increasing TFMB contents. Both experimental and molecular simulations method were adopted to discuss the influence of fluorine group on the aggregation structure and properties of PI fibers, suggesting that the improved free volume were the crucial factor responsible for low dielectric constant. The molecular ordered degree and orientation degree of co-PI fibers decreased firstly and further increased with increasing TMFB content, which is due to the combined effects of large free volume of trifluoromethyl and polymer regularity variation caused by copolymerization.

A novel star-shaped, cardanol-based bio-prepolymer: Synthesis, UV curing characteristics and properties of cured films

Starting from renewable Cardanol, a novel inherently fire-retardant UV curable bio-based prepolymer (AEHCPP) with phosphazene core and six Cardanol arms are prepared in this report. The chemical structure of all newly prepared intermediates compounds and AEHCPP are well-characterized using nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR). UV-curable mixture consisting of AEHCPP and different diluents were formulated and their photopolymerization dynamics were investigated on Photo-calorimetry (photo-DSC). The thermal properties of crosslinked coatings were estimated using thermal analysis technology. Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA) results show that glass transition temperatures of all cured films are above room temperature (>30 °C), the 5% weight loss temperature in nitrogen is higher than 266 °C. The fire-retardant properties are estimated by TGA and all calculated Limiting Oxygen Index (LOI) values are over 24, implying the excellent fire-resistance of cured films.

Branched phenyl‐s‐triazine moieties to enhance thermal properties of phthalonitrile thermosets

AbstractHeat‐resistant materials have made tremendous progress in marine, aerospace and microelectronic fields. Herein, a new class of phthalonitrile resins, branched poly(biphenyl ether triphenyl‐s‐triazine) phthalonitriles, were successfully synthesized via a two‐step, one‐pot reaction, on the basis of 2,4,6‐tris(4‐fluorophenyl)‐1,3,5‐triazine and 4,4′‐biphenol. 4,4′‐Diaminodiphenylsulfone was employed to facilitate the curing reaction, and successful realization of curing behavior was concluded from rheological and differential scanning calorimetric studies, indicating the obtained resins possess favorable processability. The relationship between concentration of reactants and properties of the resins was systematically studied. After thermal curing, the E‐glass fiber‐reinforced composite, prepared with a concentration of reactants of 0.15 g mL−1, shows an admirable glass transition temperature of 480 °C and commendable thermal stability with 5% weight loss temperature in nitrogen of 563 °C, suggesting that the improvement of the thermal properties stems from the branched structure and the phenyl‐s‐triazine units. © 2017 Society of Chemical Industry

Electromagnetic interference shielding effectiveness of microcellular polyimide/in situ thermally reduced graphene oxide/carbon nanotubes nanocomposites

A simple and effective method was adopted to fabricate microcellular polyimide (PI)/reduced graphene oxide (GO)/multi-walled carbon nanotubes (MWCNTs) nanocomposites. Firstly, microcellular poly (amic acid) (PAA)/GO/MWCNTs nanocomposites were prepared through solvent evaporation induced phase separation. In this process, PAA and dibutyl phthalate (DBP) co-dissolved in N,N-dimethylacetamide (DMAc) underwent phase separation with DMAc evaporating, and DBP microdomains were formed in continuous PAA phase. Subsequently, PAA was thermally imidized and simultaneously GO was in situ reduced. After DBP was removed, the microcellular PI/reduced GO (RGO)/MWCNTs nanocomposites were finally obtained. When the initial filler loading was 8wt%, the electrical conductivity of microcellular PI/RGO, PI/MWCNTs and PI/RGO/MWCNTs nanocomposites were 0.05, 0.02 and 1.87S·m−1, respectively, and the electromagnetic interference (EMI) shielding efficiency (SE) of microcellular PI/RGO, PI/MWCNTs and PI/RGO/MWCNTs nanocomposites were 13.7–15.1, 13.0–14.3 and 16.6–18.2dB, respectively. The synergistic effect between RGO and MWCNTs enhanced both the electrical conductivity and EMI shielding performance of the microcellular PI/RGO/MWCNTs nanocomposites. The dominating EMI shielding mechanism for these materials was microwave absorption. While the initial loading of GO and MWCNT was 8wt%, the microcellular PI/RGO/MWCNTs nanocomposite (500μm thickness) had extremely high specific EMI SE value of 755–823dB·cm2·g−1. Its thermal stability was also obviously improved, the 5% weight loss temperature in nitrogen was 548°C. In addition, it also possessed a high Young’s modulus of 789MPa.

Novel aromatic polyamides containing 2‐diphenylamino‐(9,9‐dimethylamine) units as multicolored electrochromic and high‐contrast electrofluorescent materials

ABSTRACTA series of electrochromic and photoluminescence‐active polyamides 4a‐4e were prepared from a novel dicarboxylic acid, N,N‐di(4‐carboxyphenyl)‐2‐amino‐9,9‐dimethylfluorene, and five diamines via a condensation polymerization. These polyamides were amorphous and readily soluble in many solvents. The glass transition temperatures were in the range of 281–339 °C and the 10% weight loss temperatures in nitrogen were in excess of 490 °C. The polyamides exhibited strong fluorescence in either solution or solid states. The polyamides 4a‐4d showed reversible electrochemical redox with color changing from colorless to grey‐green. Specially, the polyamide 4e with 2‐diphenylamino‐(9,9‐dimethylamine) group in both diamine and dicarboxylic acid residues exhibited multicolored electrochromic behaviors. Furthermore, the fluorescence of these polyamides could be reversibly electroswitched with a high contrast up to 221.4, enabling their potential applications in dual‐switching electrochromic/electrofluorescent materials. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 213–222

Synthesis of organosoluble and transparent phenolphthalein-based cardo poly(ether sulfone imide)s via aromatic nucleophilic substitution polymerization

A series of cardo poly(ether sulfone imide)s (PESI-C) containing bulky phthalide groups were prepared via aromatic nucleophilic substitution reaction of phenolphthalein with 4,4′-difluorodiphenyl sulfone and 4,4′-bis(4-fluorophthalimido)diphenyl ether (BFPI). The glass transition temperatures and 5% weight loss temperatures in nitrogen of the resulting PESI-C increased from 258°C to 278°C and from 468°C to 495°C with increasing the content of imide moiety in the polymer chain, respectively. These PESI-C films were transparent and essentially colorless and exhibited good mechanical properties with tensile strengths of 91–124 MPa, elongations at break of 6.9–12.8%, and tensile moduli of 2.2–2.8 GPa, respectively. It is noted that the tensile strengths, elongations at break, and tensile moduli of PESI-C also increased with increasing the content of BFPI in the copolymerization, indicating that the properties could be adjusted by controlling the ratio of BFPI and 4,4′-difluorodiphenyl sulfone.

Comparative investigations on the effects of pendent trifluoromethyl group to the properties of the polyimides containing diphenyl-substituted cyclopentyl Cardo-structure

Two series of Cardo-type polyimides (PIs), fluorinated or nonfluorinated, were prepared from condensation of the fluorinated Cardo-type diamine 1,1-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]cyclopentane (BATFPCP) or the analogous nonfluorinated Cardo-type diamine 1,1-bis[4-(4-aminophenoxy)phenyl]cyclopentane (BAPCP) with four aromatic dianhydrides PMDA, ODPA, BTDA and BPDA, respectively. Both fluorinated and nonfluorinated PIs with Cardo-structure in polymer backbone generally retained good thermal properties comparable to aromatic PIs, with glass transition temperature (Tg) of 227–270°C and 234–340°C, 5% weight loss temperature in nitrogen (air) of 471–483°C (448–474°C) and 472–482°C (464–492°C), respectively. The fluorinated and nonfluorinated PIs with Cardo-structure in the polymer backbone showed tensile strengths of 90.1–101.7MPa and 78.6–99.6MPa, tensile modulus of 1.44–1.83GPa and 1.25–1.50GPa, respectively, also comparable to those of the traditional aromatic PIs. In comparison with nonfluorinated series, the fluorinated PIs possessed better solubility, higher optical transparency and lower water absorption. The fluorinated PIs were readily soluble in a variety of organic solvents, exhibited high optical transparency and light color with the cut off wavelength at 373–424nm and transmittance at 500nm generally higher than 80%, and the water absorptions were measured as low as 0.18–0.93%. Additionally, the fluorinated series showed higher hydrophobicity by water contact angles and water absorption measurements and lower dielectric constant by dynamic dielectric measurements.

Novel poly(alkyd-urethane)s from vegetable oils: Synthesis and properties

Triglycerides of palm (Elaeis guineensis) oil, soy (Glycine max) oil and sunflower (Helianthus annuus) oil were converted to monoglycerides by glycerolysis process. The monoglycerides derived from the different oils were reacted with phthalic anhydride at 2:1 monoglyceride-to-phthalic anhydride ratio to obtain novel polyols called alkyd diols. The polyols were reacted with 4,4′-methylenediphenyldiisocyanate (MDI) to produce five novel poly(alkyd-urethane)s (PAU), namely palm oil based poly(alkyd-urethane) (POPAU), soy oil based poly(alkyd-urethane) (SOPAU), sunflower oil based poly(alkyd-urethane) (SFPAU), palm-soy oils based poly(alkyd-urethane) (POSOPAU) and palm-sunflower oils based poly(alkyd-urethane) (POSFPAU). The successful synthesis of the monoglycerides, alkyd diols and poly(alkyd-urethane)s were confirmed by FTIR, 1H NMR, 13C NMR spectroscopy and their morphology were evaluated by scanning electron microscopy (SEM). Further analyses included viscosity, solubility, iodine number testing, gel content, drying time test, thermogravimetric analysis (TGA), crosshatch adhesion tests, impact strength, pencil hardness, chemical and water resistance. Palm oil poly(alkyd-urethane) showed good thermal stability with only 5% weight loss temperature in nitrogen at 270°C. Improvements in coating performance after blending with sunflower oil or soy oil based alkyd-diols were also observed.

Synthesis, characterization and properties of TAP-6FDA hyperbranched polyimides with different branching degrees

A series of hyperbranched polyimides were successfully synthesized by condensation polymerization of A2-type dianhydride monomer 2,2-bis(3,4-dicarboxylphenyl) hexafluoropropane dianhydride (6FDA) and B′B2-type triamine monomer 2,4,6-triaminopyrimidine (TAP). Polymers with different branching degrees (DB) and terminated groups were obtained by changing the monomer addition order and the monomer molar ratio. Fourier transform infrared spectroscopy and 1H NMR were used to verify the structure of the prepared polyimides, which indicated that the amino group still existed in all the products. The DB of the polymers indicated by 1H NMR increased from 30% to 79% with the molar ratio of TAP:6FDA decreasing from 1:1 to 1:2. The absolute molecular weights were measured by size-exclusion chromatography with multi-angle laser light-scattering detection, which suggested that the highest molecular weight would be obtained when the molar ratio of amino groups:anhydride groups of the monomers was 3:3.2. With the DB increasing, the d-spacing values indicated by wide angle X-ray diffraction increased from 5.15 Å to 5.68 Å and the UV − visible spectra of the polymers exhibited decreasing cut-off wavelengths. The 5% weight loss temperature in nitrogen increased with decreasing content of TAP monomer, and the glass transition temperatures of the obtained polyimides decreased from 282 °C to 258 °C with increasing DB. © 2013 Society of Chemical Industry

Phosphorus-containing poly(trimethylene terephthalate) derived from 2-(6-oxido-6H-dibenz〈c,e〉〈1,2〉oxaphosphorin-6-yl)-1,4-hydroxyethoxy phenylene: Synthesis, thermal degradation, combustion and pyrolysis behavior

A novel phosphorus-containing poly(trimethylene terephthalate) (PTT) derived from 2-(6-oxido-6H-dibenz〈c,e〉〈1,2〉oxaphosphorin-6-yl)-1,4-hydroxyethoxy phenylene was synthesized via solid state polymerization, and its chemical structure was confirmed with 1H NMR. The thermal stability of the resulting copolyester was analyzed by thermogravimetric analysis. With the introduction of phosphorus-containing segments, polyester onset weight-loss temperatures in both nitrogen and air are enhanced. Thermal degradation kinetics were analyzed using the Flynn–Wall–Ozawa method, which showed a decreased activation energy for the copolyester compared with that for neat PTT, strongly suggesting that the increased onset weight-loss temperature in nitrogen is a result of enhanced carbonization. Microscale combustion calorimetry was carried out to test the flammability behavior of the copolyester; improved flame-retardant properties were observed with incorporated phosphorus components. Py-GC–MS testing revealed that the pyrolysis of phosphorus-containing copolyester is not significantly affected by the phosphorus incorporation.

Molecular packing and properties of poly(benzoxazole-benzimidazole-imide) copolymers

Novel random poly(benzoxazole-benzimidazole-imide) copolymers were synthesized via the poly(amic acid)s from the reaction of 5-amino-2-(4-aminobenzene)benzoxazole (BOA) and 5-amino-2-(4-aminobenzene)benzimidazole (BIA) with 3,3′,4,4′-biphenyl tetracarboxylic dianhydride (BPDA). The corresponding homopolyimides were also prepared for comparison. The resulting polyimides were characterized by different techniques to obtain their molecular packing and properties. The copolyimide films not only showed ordered arrangement of molecular chains, high packing coefficients and low water absorption, they also exhibited extremely high tensile strength (233.64–325.79 MPa) and modulus (5.18–5.75 GPa) without any stretching. The glass transition temperatures (Tgs) and 5% weight-loss temperatures in nitrogen of the copolyimides were in the range of 339–387 °C and 573–577 °C, respectively. The excellent mechanical and thermal properties of these copolyimides have been verified to be mainly attributed to the improving regularity of the interchain packing by the introduction of benzoxazole moieties as well as the enhancement of the hydrogen bonding by the incorporation of benzimidazole moieties. In addition, the copolyimide films also showed excellent adhesion to copper (637.0–960.4 N m−1) without any adhesion promoters. Meanwhile, the deviation of the experimental values of the molecular packing and properties from the expected values indicated the cooperative effects of BOA and BIA moieties on the copolyimide backbone at the molecular level.

Study on synthesis of novel soluble aromatic polyamides with pendant cyano groups

A series of novel soluble aromatic polyamides with pendant cyano groups were synthesized by low temperature polycondensation of aromatic diamines with a new monomer 2,6-bis(4-chloroformylphenoxy)benzonitrile (ClPOBN) in the presence of N,N-dimethylacetamide (DMAC) as the solvent and tertiary amines as the absorbent of HCl. The properties and structures of obtained polymers were characterized by means of FTIR, TG, and elemental analysis. Structures of prepared polymers are as expected. TG studies show that the polymers had excellent thermal stability as measured by 5% weight loss temperatures in nitrogen (409–438 °C).They are soluble in aprotic polar organic solvents such as N-methyl pyrrolidone (NMP), dimethyl sulphoxide (DMSO) and N,N-dimethylformamides (DMF) and are swelled in common solvents, such as CHCl3, ethylene dichloride (DCE), CH2Cl2, tetrahydrofuran (THF), etc. Their thin films which cast from DMF had tensile strength of 79–93 MPa, Young’s moduli of 1.7–2.6 GP, elongation at break of 9–15%, indicating they are strong in mechanical properties.

Alicyclic polyimides – a colorless and thermally stable polymer for opto-electronic devices

Alicyclic polyimides were prepared from polyalicyclic monomers using a two-step method. Light absorption of polyimides was elucidated from quantum chemistry. The alicyclic polyimide films were colorless, and the transparencies in the visible region were over 85%. The semi-aromatic polyimide films had an average refractive index range of 1.599 to 1.617, and that of a full-alicyclic polyimide was 1.522. The birefringencies were nearly zero. Semi-aromatic polyimides were soluble in aprotic polar solvents like DMAc. However, the non-aromatic (full-alicyclic) polyimides were insoluble except sulfuric acid. All the alicyclic polyimides have the 5% weight loss temperatures in nitrogen over 450 °C, and 400 °C in air. They possess glass transition temperatures over 280 °C. The alicyclic polyimide films have a tensile modulus range of 1.3–3.0 GPa, and a tensile strength range of 38–145 MPa. Especially semi-aromatic polyimide films display high strength. They have an elongation at break range 5–30%. All the polyimides exhibited amorphous patterns and broad dispersive peaks of diffraction around at 16° (2θ).

Use of Ionic Green Solvent for the Synthesis of Optically Active Aromatic Polyamides Containing a L-Leucine Moiety under Microwave Irradiation

An efficient, fast and easy method for the synthesis of new optically active and thermally stable aromatic polyamides (PAs) containing a pendant phthalimide group and L-leucine flexible side-spacer using ionic liquid (IL) by microwave irradiation, as well as conventional heating, has been investigated. ILs are outstanding microwave-absorbing agents owing to their high ionic conductivity and polarizability, thus leading to a high heating rate and a considerably shortened reaction time. The resulting PAs have a inherent viscosity in the range of 0.31–0.96 dl/g. All of the obtained polymers are readily soluble in many organic solvents and showed good thermal stability associated with high glass-transition temperatures (above 200°C), as measured by differential scanning calorimetry. Thermogravimetric analysis showed that the 10% weight-loss temperatures in nitrogen were in the range 371–380°C. The interpretation of kinetic parameters (E, ΔH, ΔS and ΔG) of thermal decomposition stages has been evaluated using Coats–Redfern equations.

Microwave-induced synthesis of new optically active and soluble polyamides containing pendent 4-(2-phthalimidiylpropanoylamino)benzoylamino-groups

An aromatic chiral diacid monomer, 5-[4-(2-phthalimidiylpropanoylamino)-benzoylamino]isophthalic acid was synthesized in five steps under conventional heating in high yield and purity. A series of soluble, thermally stable and optically active polyamides (PA)s containing pendent groups made of phthalimide, flexible L: -alanine and benzamide sequence have been successfully synthesized under microwave irradiation. Excellent yields and very short reaction time were the main characteristics of this method. The same polymerization reactions were also carried out by conventional thermal heating and the results are compared. The resulting PAs had inherent viscosity in the range of 0.50-0.79 dL g(-1). All of the these polymers are readily dissolved in various solvents such as N-methyl-2-pyrrolidinone, N,N-dimethylacetamide and N,N-dimethylformamide and showed glass-transition temperature above 200 degrees C. Thermogravimetric analysis demonstrated that the 10% weight-loss temperatures in nitrogen were 372 and 422 degrees C for selected two PAs. All of these polymers showed optical rotation which is due to successful insertion of L: -alanine in the structure of chiral diacid monomer.

Synthesis and properties of novel phosphorus‐containing poly(ether ether ketone ketone)s

AbstractA novel monomer, bis[4‐(4‐fluorobenzoyl)phenyl]phenylphosphine oxide, was synthesized through the reaction of bis(4‐chloroformylphenyl) phenyl phosphine oxide with fluorobenzene. Three poly(ether ether ketone ketone)s derived from bis[4‐(4‐fluorobenzoyl)phenyl]phenylphosphine oxide and different aromatic bisphenols were prepared by aromatic nucleophilic substitution reactions. The resulting polymers had inherent viscosities in the range of 0.55–0.73 dL/g. The structures of the poly(ether ether ketone ketone)s were characterized with Fourier transform infrared and 1H‐NMR. Thermal analysis indicated that the glass‐transition temperatures of the poly(ether ether ketone ketone)s were higher than 200°C, and the 5% weight loss temperatures in nitrogen were higher than 463°C. All the polymers showed excellent solubility in polar solvents such as N‐methyl‐2‐pyrrolidone, dimethylformamide, and dimethylacetamide and could also be dissolved in chlorinated methane. The polymers afforded transparent and flexible films by solvent casting. Organic phosphorous moieties also imparted good flame‐retardancy to the polymers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Safe and fast polyamidation of 5-[4-(2-phthalimidiylpropanoylamino)benzoylamino]isophthalic acid with aromatic diamines in ionic liquid under microwave irradiation

Ionic liquids are outstanding microwave-absorbing agents owing to their high ionic conductivity and polarizability, thus leading to a high heating rate and a considerably shortened reaction time. In this study, a series of novel optically active polyamides (PA)s with pendent 4-(2-phthalimidiyl-propanoylamino)benzamide units were prepared with excellent yields via a simple microwave heating method using 1,3-dipropylimidazolium bromide and triphenyl phosphite. In comparison with classical heating, microwave irradiation was demonstrated to be a more effective energy source. The resulting PAs have inherent viscosity in the range of 0.52–0.71dL/g. All of the polymers were readily soluble in many organic solvents and showed good thermal stability associated with high glass-transition temperatures above 200°C as measured by differential scanning calorimetry. Thermogravimetric analysis showed that the 10% weight-loss temperatures in nitrogen were 455 and 410°C, a significant improvement in thermal stability having been observed with the increase in the side-chain length.

Lyotropic Liquid Crystalline Polyamides Containing Aromatic, Heterocyclic Structures: Preparation and Properties

A series of novel lyotropic liquid crystalline polyamides derived from l,2-dihydro-2-(4-aminophenyl)-4-[4-(4-(aminophenoxyl)phenyl)]-phthalazinone (DHPZ-DA), p-phenylene diamine (PPD) and terephthaloyl dichloride (TPC) have been successfully synthesized by the low temperature solution polycondensation method. The copolymers obtained with inherent viscosity of ≈1.21 to 3.29 dl·g -1 , determined in NMP (1 wt.-% LiCI) or concentrated H 2 SO 4 at 25°C, were confirmed to be amorphous by WAXD and differential scanning calorimetry (DSC). Their solubility was improved by the introduction of non-coplanar, twisted phthalazinone moieties and ether linkages into the main chain with the result that they can be soluble in some polar solvents containing a small amount of LiCI. Their T g s were all above 310°C and 10% weight loss temperatures in nitrogen above 500°C. Most of these polyamides can form an anisotropic phase in concentrated H 2 SO 4 , NMP (1 wt.-% LiCI) and DMAc (1 wt.-% LiCI) solutions, observed on a polarizing light microscope.

Preparation and Characterization of Lyotropic Liquid Crystalline Aromatic Copolyamides Containing Twisty and Non-coplanar Moiety

A series of aromatic rigid-chain copolyamides were prepared from 1,2-dihydro-2-(4-aminophenyl)-4-[4-(4-(aminophenoxyl)phenyl)](2H)phthalazin-1-one (DHPZ-DA), p-phenylenediamine (PPD), 1,4-bis(4-aminophenoxy)benzene (BAPOB) and terephthaloyl dichloride (TPC) by low temperature solution polycondensation. The polymers were produced with high yields and relatively high inherent viscosities, ranging from 1.74 to 4.31 dL/g. The introducing of phthalazinone moiety and ether linkages into the main chain improved the solubility in some polar solvents. The Tg values of the polymers were in the range of 291–351 °C and the 5 and 10% weight loss temperatures in nitrogen were in the range of 486–518 and 509–538 °C, respectively, indicating their good thermal stability. WAXD measures indicated that these copolyamides were semicrystalline in nature. Most of the polymers exhibited nematic lyotropic liquid crystalline characteristics in concentrated H2SO4, NMP (1 wt % LiCl) and DMAc (1 wt % LiCl) solutions, as evidenced by polarizing light microscopy.