Synthesis and properties of polyketones containing thiophene links

A series of polyketones containing thiophene links was synthesized by the Friedel-Crafts polymerization of these dithienylalkanes with aromatic diacid chlorides or dicarbonyl chlorides comprising thiophene links with diphenyl compounds. The resulting polymers had inherent viscosities in the range of 0.11–0.27 dL/g and showed poor solubilities to common organic solvents except strong acids. These thiophene-based polyketones exhibited fairly good thermal stabilities. The TGA data revealed 5% weight losses at 375–450°C and residual weights at 500°C were 43–79% under nitorgen. It was found that the thermal stabilities of these polymers were superior to those of polymides or polysulfonamides containing thiophene links and almost comparable to common aromatic polyketones     

Synthesis, characterization and biological activity of polyketones

Polyketone resins have been prepared by the Friedel-Crafts polymerization of dithiophenylidenecyclopentanone (Ⅰ), dithiophenylidenecyclohexanone (Ⅱ) and dithiophenylideneacetone (Ⅲ) with adipoyl, sebacoyl and terephthaloyl dichlorides using boron trifluoride as catalyst and carbon disulphide as solvent. Polymers were characterized with IR, 1 H-NMR, and the results showed the presence of carbonyl of ketonic groups in the main chain. The polyketones have inherent viscosities of 0.40-0.70 dL/g. All the polymers are semicrystalline and most of them are partially soluble in most common organic solvents but freely soluble in aprotic solvents. The temperatures of 50% weight loss are as high as 185℃ to 280℃ in air, indicating that these aromatic polyketones have excellent thermal stability. All the polyketones were tested for their antimicrobial activity against bacteria and fungi.     

Crosslinkable aromatic polyimides containing 2,3-dicyanopyrazine rings

New crosslinkable aromatic polyimides were synthesized from 2,3-dicyano-5,6-di(aminophenyl)pyrazine ( 1b ) and 2,3-dicyanopyrazino [5,6–9,10] diaminophenanthrene ( 2b ). They were characterized by viscosimetry, IR, NMR, x-ray, DTA, TMA, TGA, and isothermal gravimetric analysis. The polyimides derived from 1b were amorphous whereas those prepared from 2b showed microcrystalline or crystalline character. The polymers were soluble in polar aprotic solvents (DMF, NMP, DMSO) at ambient temperature or upon heating. They dissolved also completely or partially in certain hot inorganic and organic acids (H₂SO₄, CCl₃COOH). Their glass transition temperatures were in the range of 257–370°C. The crosslinked polymers obtained after an appropriate thermal treatment, were stable up to 397–426°C in N₂ or air and afforded anaerobic char yields of 62–75% at 800°C. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1303–1311, 1997     

Heat-resistant polymers from melt-processable bisimido-bisphthalonitriles

Heat-resistant polymers which are processable into void-free components and suitable for composite applications have been synthesized by thermal/chemical polymerization of four newly developed bisimido-bisphthalonitriles containing silicon, ether, carbonyl, and hexafluoroisopropylidene groups. Thermal polymerization involving addition reactions was performed at 200–275°C for 2–10 h and then post-curing at 310°C for 10 h. Polymers VI, VII, VIII , and IX were obtained. The thermal polymerization was monitored using infrared spectroscopy. Thermal polymerization was also carried out in the presence of an aromatic diamine. A polyhexasocyclane ( V ) was synthesized by condensation polymerization of ether containing bisimido-bisphthalonitrile with 4,4′-diaminodiphenyl ether in solvent phenol. The synthesized polymers were evaluated for thermal stability using dynamic thermogravimetric analysis (TGA). Polymers VII, VIII, IX , and X showed thermal decomposition temperature in the range of 475–500°C in nitrogen and air atmosphere. The char yield of the polymers was in the range of 60–69% in nitrogen at 800°C. This study indicated that synthesized thermosetting polymers from ether and keto containing bisimido-bisphthalo-nitrile are potential candidates for development of graphite composites. © 1993 John Wiley & Sons, Inc.     

Bismaleimides chain-extended by imidized benzophenone tetracarboxylic dianhydride and their polymerization to high temperature matrix resins

Heat-resistant polymers were obtained by thermal polymerization of several bismaleimides or their substituted derivatives. The chain of the polymer precursors was extended by incorporation of imidized benzophenone tetracarboxylic dianhydride between the maleimide rings in order to impart a degree of flexibility in the polymers. The bismaleimides and their corresponding tetraamic acids were characterized by infrared (IR) and proton nuclear magnetic resonance (¹H-NMR) spectroscopy. The differential thermal analysis (DTA) thermograms of the monomers showed exotherms at 200–340°C attributed to the thermally induced polymerization reactions. The influence of different substituents in the maleic double bond on the curing temperature was investigated. The thermal stability of the cured resins was evaluated by thermogravimetric analysis (TGA) and isothermal gravimetric analysis (IGA). They were stable up to 367–433°C both in nitrogen and air atmosphere and afforded 57–68% char yield at 800°C under anaerobic conditions. The structure of the aromatic and aliphatic diamines utilized for imidization was correlated with the thermal stability of the cured resins. The bismaleimide derived from p-phenylenediamine gave the most heat-resistant resin because of its higher rigidity.     

Development of Oligomeric Phthalonitrile Resins for Advanced Composite Applications

Phthalonitrile endcapped oligomers containing aromatic ether and imide linkages have been synthesized and characterized. The phthalonitrile terminated oligomers were prepared in two step (one spot) method by the reaction of an excess amount of pyromellitc dianhydride (PMDA) with aromatic diamines, in a N,N-dimethylacetamide (DMAc)/toluene solvent mixture to form anhydride terminated oligomeric intermediate that was terminated by the reaction with 4-(aminophenoxy) phthaloitrile. The average molecular weights of the prepared oligomers were determined by GPC analysis. The oligomeric phthalonitrile monomers have been converted to network polymers using 4,4'-diaminodiphenyl sulfone (DDS) (5.0 wt %) curing additive at elevated temperatures. Differential scanning calorimetric (DSC) analysis was used to follow the polymerization as the oligomeric phthalonitrile/diamine mixtures and prepolymers. An isothermal rheometric analysis was conducted to determine the complex viscosity of the prepolymers during polymerization reaction. Viscosity increases as a function of time due to crosslinking, which depends upon the concentration and reactivity of the curing agent. The TGA analysis of cured resins showed superior thermal and thermo-oxidative stability. The temperature of 10% weight loss from TGA are in the range of 498-511 °C in N₂ and 448–461 °C in air atmosphere. Char yield at 800 °C is 41.7–50.2% in air and 70.6–83.1% in N_2.     

Synthesis and properties of semi-interpenetrating network based on styrene-acrylonitrile-vinyl acetate terpolymer and zinc acrylate

Semi-Interpenetrating polymer network materials (semi IPNs) have been synthesized from styrene-acrylonitrile-vinyl acetate terpolymer as polymer I and zinc acrylate as polymer II, using divinyl benzene as crosslinking agent for polymer II. The terpolymer was pre-synthesized by a radical polymerization method using AIBN as the radical initiator. The terpolymer has been characterized by IR and elemental analysis. The composition (Sty: AN:VAc) = (0.25:0.50:0.25), the intrinsic viscosity (0.16 dl/g), the softening temperature range (180–185 °C), the glass transition temperature (23 °C) and the thermal stability (up to 300 °C) of the terpolymer were determined. The IPN was characterized by determining its density (1.12 g/cc at 30 °C), molecular weight between crosslinks (M_c = 1469), thermal stability (~ 400 °C), glass transition temperature (41 °C, 78 °C) and two-phase morphology.     

Thermostable laminating resins based on aromatic diketone bis- and tetramaleimides

Twelve structurally different bis- and tetramaleimides were synthesized by Friedel–Crafts reaction between 4-maleimido-benzoylchloride or 3,5-bismaleimido-benzoylchloride and various aromatic reagents. They were characterized by infrared (IR) and proton nuclear magnetic resonance (¹H-NMR) spectroscopy. Crosslinked resins were obtained by curing the monomers at 250°C/6 h. Thermal characterization of monomers and cured resins was accomplished by differential thermal analysis (DTA), dynamic thermogravimetric analysis (TGA), and isothermal gravimetric analysis (IGA). Tetramaleimides were polymerized at lower temperatures than did the respective bismaleimides. The cured resins were stable up to 317–385°C in N₂ atmosphere and formed an anaerobic char yield of 52–66% at 800°C.     

Poly(imide ether sulphone) as new soluble high performance polymer

Poly(imide ether sulphone) as novel high-performance polymer has been obtained by the condensation polymerization of 4,4'-bis(4-fluorophthalimido) diphenyl ether with 4,4'-sulfonyldiphenol via aromatic nucleophilic substitution reaction. Its structure was confirmed by means of FTIR and NMR spectroscopy, elemental analysis. Differential scanning calorimetry and thermal analysis measurements showed that synthesized polymer possessed high glass transition temperature (T_g = 210°C) and good thermal stability with high decomposition temperatures (T_d > 480°C). Prepared polymer film showed good light transmittance and mechanical strength.     

Bismaleimides and bisnadimides derived from 2,5-bis(4-aminophenyl)-3,4-diphenylthiophene and their polymerization to heat-resistant matrix resins

Six new structurally different bismaleimides or bisnadimides based on 2,5-bis(4-aminophenyl)-3,4-diphenylthiophene (BADT) were synthesized and characterized by infrared (IR) and proton nuclear magnetic resonance (¹H-NMR) spectroscopy. Chain-extension of several bismaleimides was accomplished by incorporating various imide, amide, and urea groups. The bismaleimide and bisnadimide prepared by reacting BADT with maleic or nadic anhydride, respectively, were soluble in various organic solvents. The monomers were thermally polymerized or by a Michael reaction with certain aromatic diamines. Curing behavior was investigated by differential thermal analysis (DTA). The thermal and thermo-oxidative stability of polymers was evaluated by dynamic thermogravimetric analysis (TGA) and isothermal gravimetric analysis (IGA). The polymers derived from bismaleimide of BADT as well as from the bismaleimides chain-extended by imide groups were stable up to 355–392°C in N₂ or air and afforded anaerobic char yield 66–74% at 800°C. The polymers obtained by curing the bismaleimide-diamine adducts showed a relatively lower thermal stability.     

Novel processable aromatic thermoplastic polyimides: Films,adhesives, moldings,and graphite composites

Novel hot-melt type flexible, tough, thermally stable, processable, thermoplastic, aromatic polyimides have been synthesized involving reaction of a keto-ether containing diamine with hinged aromatic dianhydrides followed by thermal and chemical cyclodehydration. Inherent viscosity in DMAC at 35°C of the synthesized polymers ranged 1.02 to 1.4 dl/g (0.5% solution). The polymers showed a glass transition temperature (T_g) of 250°C to 180°C as determined by differential scanning calorimetry (DSC) and thermomechanical analysis (TMA). Thermogravimetric analysis showed polymer stability up to 510°C, in both air and nitrogen atmospheres. All the polymers have shown good melt-flow. Films of 1.5–2.8 ml thickness were made and tested for mechanical properties at room temperature, 177°C and 210°C. The developed films are suitable for adhesion of Ti/Ti specimens and showed a lap shear strength of 5575 psi. Melt-fusion of the polymers gave tough moldings. Graphite cloth composites have been made and tested for mechanical properties.     

Benzocyclobutene in polymer synthesis. I. Homopolymerization of bisbenzocyclobutene aromatic imides to form high-temperature resistant thermosetting resins

A series of new bisbenzocyclobutene-terminated aromatic imide monomers has been synthesized from the condensation reaction of 4-aminobenzocyclobutene and the perspective dianhydride in refluxing acetic acid/toluene. The differential scanning calorimetric studies of the foregoing monomers indicated that polymerization exotherms began at 229–250°C and reached their maxima at 258–263°C. The cured samples (250–254°C; N₂; 8 h) were surprisingly stable toward thermo-oxidative degradation; only 7–10% weight loss was observed after 200 h (in air) at 314°C (600°F). At higher temperatures (650 and 700°F), the most rigid structure was the most thermo-oxidatively stable. An approach to enhance both the final glass-transition temperature (T_g cure) and the thermo-oxidative stability of the bisbenzocyclobutene system was to dilute the cure-site density since the cure-site structure is the weakest part of the polymeric structure. Therefore, a series of bisbenzocyclobutene-terminated aromatic imide oligomers were prepared, using various aromatic amines as the chain-extending agents. Meta-phenylenediamine was apparently the most effective in the advancement of both the T_g (cure) and thermo-oxidative stability.     

Bis-, tris-, and tetrakis-maleimidophenoxy-triphenoxycyclotriphosphazene resins for fire- and heat-resistant applications

Novel fire- and heat-resistant polymers was obtained by the thermal polymerization of various maleimidophenoxy-triphenoxycyclotriphosphazenes. These polymers, in which the cyclic triphosphazene structure is preserved, have thermal stability to 350°C and char yields of 82–78% at 800°C in nitrogen and 78–71% at 700°C in air. Two groups of monomers were synthesized by reacting tris(4-aminophenoxy)-tris(phenoxy)cyclotriphosphazene with maleic anhydride alone or in combination with benzophenonetetracarboxylic or pyromellitic dianhydride. The structures of cyclic phosphazene-trimeric precursors and the polymers were characterized by Fourier-transform infrared, proton nuclear magnetic resonance, and elemental analysis. The thermal stabilities of the polymers were evaluated by thermogravimetric analysis.     

Fluorescence,Thermal, Electrochemical,and Morphological Properties of New Poly(Urethane-İmide)s: Synthesis and Characterization

New thermally stable poly(urethane-imide)s (PUIs) were synthesized to investigate aliphatic and aromatic group effects on various properties such as thermal stability and electrochemical properties. Thermal characterizations were carried out by TG-DTA and DSC techniques. TGA results showed that the PUIs derived from aromatic diisocyanates had relatively higher thermal stabilities as compared to the aliphatic diisocyanate. They have between 223–245°C onset temperature and above 37% char at 1000°C. Also, thermal degradation values show that PUIs have higher stability than conventional PU. DSC results showed that the new PUIs have Tg values between 134 and 138°C. Fluorescence measurements were performed using dimethyl sulfoxide solutions and also, the optimization of the concentrations maximal emission intensity was investigated in dimethyl sulfoxide. As a result, the remarkable properties related to the fluorescence and thermal measurements of the polymers were obtained. Therefore, these polymers could be used in various application fields because of the fluorescent and thermal properties.     

Cationic polymerization behavior of isobutyl vinyl ether with arenesulfonates as non‐salt‐type latent thermal initiators

Substituted and unsubstituted benzenesulfonic acid cyclohexyl esters (1–7) were synthesized, and their possibility as latent thermal initiators in the cationic polymerization of isobutyl vinyl ether (IBVE) was examined to develop novel non‐salt type latent cationic initiators. Thermal decomposition of cyclohexyl p‐nitrobenzenesulfonate (2) in C₆D₆ at 80°C proceeded to exclusively afford cyclohexene as well as p‐nitrobenzenesulfonic acid. Cationic polymerization of IBVE with 1 mol % of an arenesulfonate (1–6) in bulk was carried out at 40–100°C for 12 h. No polymerization took place below 50°C, while the consumption of IBVE depending on both the polymerization temperature and the structure of the arenesulfonates was observed above 60°C. The obtained polyIBVEs showed bimodal GPC curves in several cases, revealing the intervention of two independent propagation species in the polymerization. The cationic polymerization of IBVE with cyclohexyl 2,4,6‐triisopropylbenzenesulfonate (7) at 80°C confirmed the acceleration effect of bulkiness on the polymerization rate. It was concluded that the polymerization was largely dependent on both electronic and steric factors of the aryl groups of the initiators which were directly related to the stability of the sulfonate anions. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 293–301, 1999     

Synthesis and diels–alder polymerization of furfurylidene and furfuryl-substituted maleamic acids

The reactions of monomaleamic acid derived from an aromatic diamine with furfural afforded a novel class of furfurylidene-substituted maleamic acids 2a–2d . The latter were cyclodehydrated to yield maleimides 3a–3d which are AB-monomers for a Diels–Alder polymerization. In addition, N-furfurylmaleamic acid ( 4 ) was synthesized by reacting furfurylamine with maleic anhydride at ambient temperature. Cyclodehydration of 4 afforded N-furfurylmaleimide ( 5 ). The polymer precursors were characterized by IR and ¹H-NMR spectroscopy. Their curing behavior was investigated by DTA and correlated with chemical structures. Diels–Alder polymerization of monomers occurred at the temperature range of 113–210°C. Thermal stability of monomers was evaluated by TGA and isothermal gravimetric analysis (IGA). It was shown that thermal stability of the polymer derived from maleamic acid 4 was dramatically improved upon curing at high temperatures due to the formation by dehydration of a stable aromatic structure.     

Polyamides incorporating phosphine oxide groups. I. Wholly aromatic polymers

Five novel polyamides incorporating phosphine oxide groups have been synthesized by the condensation reaction of bis(4-carboxyphenyl)phenylphosphine oxide with a series of aromatic diamines. The thermal properties of these polymers were investigated by differential scanning calorimetry and thermogravimetric analysis. Glass transition temperatures in the 225–254°C range were recorded, together with good thermooxidative stability (5% weight loss occurring at >420°C) and high char yield upon prolonged heating at 650–800°C (24–50%). Also, good solubility in aprotic polar solvents was observed for all polyamides synthesized. © 1996 John Wiley & Sons, Inc.     

Regeneration of polycondensation of wholly aromatic poly(azomethine)s with 1,5‐ or 2,6‐substituted naphthalene moiety in main chain

Wholly aromatic poly(azomethine)s with 1,5‐ or 2,6‐substituted naphthalene moiety in the main chains were prepared in aprotic polar solvents or m‐cresol under various reaction conditions. In the polymerization of 1,5‐diaminonaphthalene with terephthalaldehyde, the polymer that synthesized in (HMPA/DMSO) at room temperature for 24 h by adding 5 wt % of calcium chloride and a very small amount of p‐toluenesulfonic acid showed the highest reduced viscosity in all of the polymers from 1,5‐diaminonaphthalene. The reduced viscosity of poly(azomethine)s synthesized from 2,6‐diaminonaphthalene with 2,6‐diformylnaphthalene in m‐cresol and with terephthalaldehyde in HMPA/DMSO were η_red = 0.35 and 0.36, respectively. The thermal analysis showed the poly(azomethine)s had high thermal stability and the glass‐transition temperatures of these polymers are about 250 °C. The X‐ray diffraction showed that they are partially crystalline. They could be polymerized again by second stage polycondensation in polyphosphoric acid. The reduced viscosities of the obtained polymers were about 2–5 times as high as that of the pristine polymers. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1064–1072, 2000     

Cyclopolycondensations

Fully aromatic polyquinazolinediones of high molecular weight were prepared by the cyclopolycondensation reaction of 4,4′-diamino-3,3′-biphenyldicarboxylic acid with aromatic diisocyanates. The poly(phosphoric acid) solution polymerization techniques yielded tractable poly(urea acid), which was converted to polyquinazolinediones by thermal cyclodehydration at 300–400°C. under reduced pressure. The polyquinazolinediones thus obtained have excellent thermal stability both in nitrogen and in air. The poly(urea acid) is soluble in dimethyl sulfoxide, and films can be cast from the polymer solution of poly(urea acid) (η_inh = 0.8 to 1.8). The films are made tough by being heated in nitrogen or under reduced pressure at 300–400°C. The polymerization mechanism of the cyclopolycondensation reaction was studied, and it was established that the polymerization proceeded through the formation of tractable poly(urea acid), Structure (I), of high molecular weight, followed by cyclodehydration, yielding poly(1,2-dihydro-2-imino-4H-3,1-benzoxazin-4-one), Structure (II). On subsequently being heated this undergoes intramolecular rearrangement along the polymer chain, giving the thermodynamically stable polyquinazolinedione, Structure (III).     

Preparation of phosphorus-containing polymers—XXIII: Phenoxaphosphine-containing polyimides

New phenoxaphosphine-containing polyimides were synthesized from 10-phenylphenoxaphosphine-2,3,7,8-tetracarboxylic dianhydride 10-oxide (IV) and diamines via polyamic acids in two steps. (IV) was prepared by dehydration of 10-phenylphenoxaphosphine-2,3,7,8-tetracarboxylic acid 10-oxide (III) derived from 2,3,7,8-tetramethyl-10-phenylphenoxaphosphine (I) or 2,3,7,8-tetramethyl-10-phenylphenoxaphosphine 10-oxide (II) by pyridine-permanganate oxidation. (I) was synthesized from bis(3,4-dimethylphenyl)ether and phenylphosphonous dichloride by the Friedel-Crafts reaction. The resulting polyimides had reduced viscosities of 0.13–0.84 di/g in cone H₂SO₄ at 30°. They were also soluble in dichloroacetic acid and some of them dissolved in DMA, DMSO. DMF and chloroform. Aromatic phenoxaphosphine-containing polyimides exhibited excellent thermal properties and hardly degraded below about 500°; the aliphatic polyimides decomposed at around 500. The aromatic polyimides had thermal stability similar or superior to aromatic polypyromellitimides and better heat resistance than linear open-chain phosphorus-containing polyimides. These polyimides showed retardance to inflammation.