Polymer Solvents For Electrochemical Reactions

Solubility of inorganic salts and potential window of poly(ethylene oxide) (PEO) were analyzed. Sufficient potential window (?1.6 to + 1.6 V vs Ag) was obtained for salt-containing PEOs when the ionic conductivity of the PEOs was higher than 3.0 × 10^?4 S/cm. PEO was then used as a polymer solvent for electrochemical redox reactions of heme proteins. Myoglobin was solubilized in salt-containing PEO oligomers only after PEO modification, and their reversible redox reactions were confirmed. The electrochemical reduction was slow because of the very low diffusion coefficient of the proteins in PEO oligomers. PEO-modi-fied myoglobin and hemoglobin showed reversible electron transfer reaction with ITO glass electrode at even 80 or 100°C in PEO oligomers.     

Synthesis and ring‐opening polymerization of co‐cyclic(aromatic aliphatic disulfide) oligomers

An effective approach was presented for the synthesis of co‐cyclic(aromatic aliphatic disulfide) oligomers by catalytic oxidation of aromatic and aliphatic dithiols with oxygen in the presence of a copper‐amine catalyst. The aromatic dithiols can be 4,4′‐oxybis(benzenethiol), 4,4′‐diphenyl dithiol, 4,4′‐diphenylsulfone dithiol. The aliphatic dithiols can be 1,2‐ethanedithiol, 2,3‐butanedithiol, 1,6‐hexane dithiol. The co‐cyclic(aromatic aliphatic disulfide) oligomers were characterized by gradient HPLC, MALDI‐TOF‐MS, GPC, ¹H‐NMR, TGA, and DSC techniques. The glass transition temperatures of these co‐cyclics ranged from ?11.3 to 56.6°C. In general, these co‐cyclic(aromatic aliphatic disulfide) oligomers are soluble in common organic solvents, such as CHCl₃, THF, DMF, DMAc. These co‐cyclic oligomers readily underwent free radical ring‐opening polymerization in the melt at 180°C, producing linear, tough and high molecular weight poly(aromatic aliphatic disulfide)s. The glass transition temperatures of these polymers ranged from ?3.7 to 107.8°C that are higher than those of corresponding co‐cyclics. Copyright © 2003 John Wiley & Sons, Ltd.     

Proton-transfer polyaddition reactions in syntheses of linear,branched, and functionalized poly(p-divinyl aromatics). I. Synthesis,kinetics, and mechanism of formation of linear unsaturated poly[bis(p-vinylphenyl) ether]

A peculiar step-growth (cationic) polymerization of bis(p-vinylphenyl) ether (BVPE) in nonpolar or slightly polar aromatic solvents in the temperature range from 70 to 150°C in the presence of 2.5–5.0 mmol/L of p-toluenesulfonic acid has been studied. Optimum polymerization conditions were found. New linear unsaturated polymers of BVPE with terminal vinyl groups and weight-average molecular weight from 1500 to 10,000 were obtained. The structure and the formation mechanism of these oligomers and polymers were established, and the accompanying side reactions were considered. The rate constants were measured for eight temperatures, and the activation energy was found to be −42 kJ/mol. The optimum polymerization temperature was about 80°C. © 1996 John Wiley & Sons, Inc.     

Polymerization of aromatic hydrocarbons with sulfur

The polymerization reactions of elemental sulfur with the polynuclear aromatic hydrocarbons pyrene and chrysene were studied. Heating the hydrocarbons with sulfur produces a series of sulfur-containing oligomers in which the aromatic ring systems remain intact. Polymerization is effected through the dehydrogenative action of sulfur and leads to thermally stable five- or six-membered heterocyclic ring systems. The major loss of sulfur during subsequent heat treatment occurs only at carbonization temperatures above 1000°C.     

Synthesis of Polymers by Using Divalent Metal Salts of Mono(hydroxyethyl) Phthalate: Metal-Containing Three-Dimensional Polyesters from Metal Salts,Pyromellitic Dianhydride,and Epoxides

Syntheses of metal-containing three-dimensional polyesters were investigated by the reactions of divalent metal salts of mono(hydroxyethyl) phthalate-pyromellitic dianhydride-epoxide in DMF at 90° C. The metal carboxylate groups of these metal salts catalyzed the reactions. Systems with low metal salt content gelled during reaction. The yield of the products obtained by precipitating or washing with water increased with decreasing metal salt content in the feed. The products were metal-containing, three-dimensional polyesters containing ionic links; they were slightly yellow powdery materials. Hydroxyl values of the products were much higher than the values of acidity. Inherent viscosities (in DMF at 30° C) of the products obtained from the systems which did not gel were low, ranging from 0.031 to 0.083. The thermal stability of the products showed a tendency to increase with decreasing metal salt content in the feed.     

N-alkyl-4-(N′,N′-dialkylamino)pyridinium salts: thermally stable phase transfer catalysts for nucleophilic aromatic displacement

N-Alkyl salts of 4-dialkylaminopyridines are effective phase transfer catalysts which are up to 100 times more stable than tetrabutylammonium bromide to conditions encountered in nucleophilic aromatic substitution reactions. These salts are thermally stable to over 300°C, and promote reactions in non-polar solvents (or in the absence of solvent) at temperatures as high as 200°C.     

Synthesis of wholly aromatic polysulfonamides from aromatic disulfonyl chlorides and aromatic diamines

Wholly aromatic polysulfonamides of high molecular weight were prepared by the solution poly-condensation of aromatic disulfonyl chlorides with aromatic diamines in tetramethylene sulfone and substituted pyridines as the acid acceptor. Polysulfonamides with inherent viscosities as high as 1.2 were readily obtained by initiating polycondensation at a temperature of 5–10°C to control the side reactions. The polycondensation was fairly fast and was completed in 10 min at 60°C. All the aromatic polysulfonamides dissolved in a wide range of solvents, including acetone and tetrahydrofuran. These polymers were less thermally stable than the corresponding aromatic polyamides.     

Efficient Synthesis of Alkyl End‐Capped Oligoheterocycles via the Use of Palladacycle Catalyst

The preparation of mixed thiophene/furan oligomers with alkyl groups at α,α′‐position by the method which we discovered recently in our lab is presented. Thus, the mixed thiophene/furan oligomers can be prepared in good yields from monoiodoarene in the presence of 5 mol % of palladacycle catalyst and 1.2 equiv of N,N‐diisopropylethylamine in DMF at 100°C for 8 h.     

Curing of epoxy oligomers by the eutectic mixture of aromatic amines

Kinetics of curing of structurally different epoxy oligomers (ED-20 and PDI-3AK resins) in a mixture with other low-molecular-weight epoxy oligomers and plasticizers by the eutectic mixture of aromatic amines UP-0638/1 is studied by the DSC method. The activation energy and the heats of curing reactions are determined. It is established that crosslinked epoxy polymers cured at moderate temperatures (40–80°C) are strong moisture-resistant compositions with different mechanical characteristics. Plasicized elastomers based on PDI-3AK resin with glass transition temperatures of ?78 and ?95°C are freeze-and heat-resistant materials.     

Synthesis and properties of Ortho-linked aromatic polyamides based on 4,4′-(2,3-naphthalenedioxy) dibenzoic acid

A novel aromatic dicarboxylic acid monomer, 4,4′-(2,3-naphthalenedioxy)-dibenzoic acid ( 3 ), was prepared by the fluorodisplacement reaction of p-fluorobenzonitrile with 2,3-dihydroxynaphthalene in N,N-dimethylformamide (DMF) in the presence of potassium carbonate followed by alkaline hydrolysis of the intermediate dinitrile. A series of novel aromatic polyamides containing ortho-linked aromatic units in the main chain were synthesized by the direct polycondensation of diacid 3 and a variety of aromatic diamines using triphenyl phosphite and pyridine as condensing agents in the N-methyl-2-pyrrolidone (NMP) solution containing dissolved calcium chloride. The resulting polyamides had inherent viscosities higher than 0.74 and up to 2.10 dL/g. All of these polyamides were soluble in polar solvents, such as NMP, DMF, N,N-dimethylacetamide (DMAc), and dimethyl sulfoxide. Transparent, flexible, and tough films could be cast from their DMAc or NMP solutions. The solvent-cast films had high tensile strengths and moduli. Extensions to break were relatively low, except for the polymers derived from 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane and 3,4′-oxydianiline, which had elongations of 82 and 62%, respectively. Except for the polyamide based on p-phenylenediamine, all the other polyamides were amorphous in nature. All the polymers are thermally stable to temperatures in excess of 450°C in either air or nitrogen atmosphere. The polymers exhibited glass transition temperatures ranging from 183 to 260°C and decomposition temperatures (10% weight loss) ranging from 462–523°C in air and 468–530°C in nitrogen. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 3385–3391, 1997     

Synthesis and characterization of aromatic polymers containing pendant silyl groups. II. Aromatic polyamides

In order to improve the solubility of aromatic polyamides without significant loss of thermal stability, synthesis of aromatic polyamides containing pendant silyl groups was carried out by direct polycondensation of silylated aromatic diacids such as 2-trimethylsilylterephthalic acid (TSTA), 2,5-bis (trimethylsilyl) terephthalic acid (BTSTA), 5-trimethylsilylisophthalic acid (TSIA), 5-dimethylphenylsilylisophthalic acid (DMSIA), and 5-triphenylsilylisophthalic acid (TPSIA) with various aromatic diamines. The resulting polyamides had inherent viscosities in the range of 0.18–1.10 dL/g and showed improved solubilities toward aprotic polar solvents such as NMP, DMF, DMSO, etc. The prepared aromatic polyamides exhibited fairly good thermal stabilities, which were almost comparable to those of corresponding nonsubstituted aromatic polyamides. That is, thermogravimetric analysis (TGA) data revealed 10% weight losses at 358–500°C and residual weights at 700°C were 46–67% under nitrogen atmosphere. © 1992 John Wiley & Sons, Inc.     

Dehydration of lithium iodide crystal hydrate in vacuum

Dehydration of the LiI · 3H₂O crystal hydrate in vacuum has been investigated at 20–25°C. The decomposition of the LiI · 3H₂O crystal hydrate in vacuum proceeds to monohydrate. During heating of lithium iodide monohydrate, evolution of water vapor is observed at 30–100 and 100–170°C. Above 200°C, evolution of molecular oxygen is observed, possibly, because of the decomposition of lithium peroxide that is formed in side reactions during the decomposition of lithium iodide crystal hydrate.     

Polycondensations of Substituted Maleic Anhydrides and 1,6-Hexanediol Catalyzed by Metal Triflates

Polycondensations of methylmaleic anhydride (citraconic anhydride, CiAh), bromomaleic anhydride (BMaAh), and dichloromaleic anhydride (DCMaAh) with 1,6-hexanediol were conducted in bulk. For polycondensations of CiAh, the triflates of aluminum, bismuth, lanthanum, magnesium, samarium, and scandium were used as catalysts and the best results were obtained with Bismuth triflate. MALDI-TOF mass spectra indicated that the chain growth was limited by cyclization and incomplete conversion, but temperatures above 100°C were not advantageous due to side reactions. Bismuth and samarium triflate catalyzed polycondfensations of BMaAh and DCMaAh were less successful than polycondensations of CiAh. For polycondensations of CiAh, BMaAh, and DCMaAh, only a low extent of isomerization to trans isomers (1–3%) was observed at 100°C, but considerably higher extent at 140°C.     

Synthesis of poly(benzoxazole)s by direct polycondensation of dicarboxylic acids with 3,3′-dihydroxybenzidine dihydrochloride using phosphorus pentoxide/methanesulfonic acid as condensing agent and solvent

A convenient method for the synthesis of poly(benzoxazole)s of high molecular weights has been developed. These polymers were prepared readily by direct polycondensation of aromatic dicarboxylic acids containing phenyl either structure with 3,3′-dihydroxybenzidine dihydrochloride using phosphorus pentoxide/methanesulfonic acid (PPMA) as condensing agent and solvent. Polycondensations proceeded fast and was completed within 5 h at 140°C and produced poly(benzoxazole)s with inherent viscosities up to 4.6 dL/g. Model compound work was performed in detail to demonstrate the feasibility of the reaction for polymer formation. The thermogravimetry of the aromatic poly(benzoxazole)s showed 10% weight loss in air and nitrogen at 450–505°C and 465–535°C, respectively.     

Methylsiloxane Oligomers with Oxyalkyl Fragments in the Side Chain

The dehydrocondensation reactions of α,ω–bis(trimethylsiloxy)methylhydridesiloxane with saturated primary n-alcohols in the presence of anhydrous powder-like potassium hydroxide or platinum on the carbon (Pt/C-5%) at 1:30 ratio of initial compounds, at various temperature (40–60 °C) was carried out, and methylsiloxane oligomers with n-alkyloxy substituted groups in the side chain were obtained. It was shown that completely dehydrocondensation of all active Si H groups do not take place. Dehydrocondensation reaction order, activation energy and rate constants were found. The synthesized oligomers were characterized by ¹H, ¹³C NMR, Cosy and FTIR spectra data. Gel-permeation chromatography, differential scanning calorimetric, thermogravimetric and wide-angle X-ray investigations of synthesized oligomers were carried out.     

Thermally reversible polymer linkages. II. Linear addition polymers

The stepwise addition polymerization reactions of bisazlactones [bis(2-oxazolin-5-one)s] and a variety of 4,4′-bisphenols have been studied for the purpose of making thermally reversible linear polymers. Thus polymerization occurs at or near room temperature, while depolymerization yielding the two monomer species occurs at elevated temperatures. The synthesis of oligomers in solution without the use of catalyst occurs for the reaction of bisazlactones with bisphenols containing an electron-withdrawing moiety between the two phenol groups of the bisphenol. These oligomers regenerate the bisphenol and bisazlactone monomers upon heating to 165–200°C for several hours under dry box conditions. In many cases, these reactions follow the same patterns of reactivity observed in model studies. This chemistry may be useful for forming degradable or recyclable polymers, where shortchain prepolymers, or macromonomers, endcapped with azlactone and phenol moieties could be used to form high molecular weight polymers that are thermoreversible. Such a reaction system might also be used for preventing reactions of bisphenols and/or bisazlactones at low temperatures, with the desired reaction initiated by formation of the reactive species at elevated temperatures. Envisioned uses in this case might be thermally triggered crosslinking or polymerization reactions, or temperature controlled drug release. © 1993 John Wiley & Sons, Inc.     

Efficient synthesis and characterization of novel bis-heterocyclic derivatives and benzo-fused macrocycles containing oxazolone or imidazolone subunits

Bis(3-(arylthiomethyl)benzaldehydes), linked to aliphatic spacers via ethers, were prepared and used as key synthons for the bis(2-phenyloxazol-5(4H)-ones) via their reaction with benzoylglycine in acetic anhydride in the presence of fused sodium acetate at 100°C for 6 hours. Bis(oxazol-5(4H)-ones) were reacted with the appropriate aromatic or heterocyclic amines in glacial acetic acid in the presence of fused sodium acetate at 100°C for 24 hours to afford a novel series of bis(2-phenylimidazol-4-ones) and their related hybrids with benzo[d]thiazole and pyrimidine-2,4(1H,3H)-dione. Moreover, bis(oxazol-5(4H)-ones) reacted with (4-aminobenzoyl)glycine to afford bis[(4-(5-oxo-1H-imidazol-1-yl)benzoyl)glycine] derivatives followed by their reaction with anisaldehyde in acetic anhydride containing fused sodium acetate at 100°C for 12 hours to afford bis(5-oxo-1H-imidazol-1-yloxazol-5(4H)-one) hybrids. Furthermore, bis(3-(arylthiomethyl)benzaldehydes) were reacted with 2,2′-(terephthaloylbis(azanediyl))diacetic acid in acetic anhydride containing fused sodium acetate at 100°C for 12 hours to give benzo-fused macrocycles containing oxazolone subunits which reacted with appropriate aromatic amines in DMF and glacial acetic acid containing fused sodium acetate at 100°C for 24 hours to give benzo-fused macrocycles containing imidazolone subunits.     

N‐methylolmaleimide–benzene photoadduct: A novel monomer for the synthesis of functionally modified polyimides

A novel polycyclic dihydroxy diimide monomer was synthesized through the photocycloaddition of N‐methylolmaleimide to benzene and the reaction of maleimide–benzene photoadduct with formaldehyde. The monomer, which evolved formaldehyde at about 165 °C, was subsequently used to prepare low molecular weight polyamineimides and polyurethaneimides. Soluble polyamineimides, prepared with three different aromatic diamine monomers, exhibited initial decomposition temperatures between 277 and 329 °C and glass‐transition temperatures between 180 and 219 °C. An aliphatic polyamineimide prepared from 1,6‐hexanediamine was insoluble and had glass‐transition and initial decomposition temperatures of 225 °C and 294 °C, respectively, with prior loss of formaldehyde from end groups. Polyurethaneimides prepared with two aromatic diisocyanates showed loss of formaldehyde in the approximate range of 160–169 °C followed by loss of CO₂ and glass‐transition temperatures of 219 and 233 °C. Attempts to prepare polyamideimides resulted in oligomers with a low nitrogen content. Attempts to prepare polyesterimides were unsuccessful. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2645–2651, 2000     

New oligomeric poly(ether-imide)s containing diphenylsilane and dibenzofuran moieties. Synthesis and characterization

A new aromatic diamine, 2,8-di(4-aminophenyl)dibenzofuran, was synthesized through the Suzuki C-C coupling reaction. This compound and an analoge diamine also based on a dibenzofuran moiety reacted with silylated-dianhydrides to yield three aromatic oligomeric poly(ether-imide)s (PEIs). The new diamine and the oligomers were characterized by elemental analysis, FT-IR, and NMR. Additionally, for the samples, solubility in an organic polar solvent was stablished and inherent viscosity values as an indirect measure of the molecular size were recovered. Some properties of PEIs were established and related to the specific structure of the repeating unit. In this sense, the rigidity/flexibility of the main chain fragments and the volume of groups bonded to silicon atom were responsible for the final properties of the polymers. All PEIs were obtained in high yield, but the inherent viscosities values of the soluble samples were low, indicating probably, low to moderated molecular sizes. The thermal decomposition temperatures measured by TGA varied from 490 to 562°C, and the Tg values ranged between 205 and 218°C. The solubility of all samples was tested in a series of common organic solvents at room temperature and at 40°C. The optical transparency in solution for the soluble samples was also determined.     

Donor-Acceptor Complexes in Copolymerization. XXVI. Effect of Solvent,Temperature, and Complexing Agent on the Polymerization of Comonomer Charge Transfer Complexes

The copolymerization of styrene with methyl methacrylate (S/MMA = 4/1) or acrylonitrile (S/AN = 1/1) in the presence of ethylaluminum sesquichloride (EASC) yields 1/1 copolymer in toluene or chlorobenzene. In chloroform the S-MMA-EASC polymerization yields 60/40 copolymer while the S-AN-EASC polymerization yields 1/1 copolymer. In the presence of EASC, styrene-α-chloroacrylonitrile yields 1/1 copolymer (DMF or DMSO), S-AN yields 1/1 copolymer (DMSO) or radical copolymer (DMF), S-MMA yields radical copolymer (DMF or DMSO), α-methylstyrene-AN yields radical copolymer (DMSO) or traces of copolymer (DMF), and α-MS-methacrylo-nitrile yields traces of copolymer (DMSO) or no copolymer (DMF). When zinc chloride is used as complexing agent in DMF or DMSO, none of the monomer pairs undergoes polymerization. However, radical catalyzed polymerization of isoprene-AN-ZnCl₂ in DMF yields 1/1 alternating copolymer. The copolymerization of S/MMA in the presence of EASC yields 1/1 alternating copolymer up to 100°C, while the copolymerization of S/AN deviates from 1/1 alternating copolymer above 50°C. The copolymerization of S/MMA deviates from 1/1 copolymer at MMA/EASC mole ratios above 20 while the copolymerization of S/AN deviates from 1/1 copolymer at MMA/EASC ratios above 50.