“One-pot” synthesis of poly(amide-imide)s derived from trimellitic acid monoesters and multiring aromatic diamines

Aromatic processable poly(amide-imide)s have been prepared according to the Yamazaki and Higashi phosphorylation reaction from flexible aromatic diamines and a mixture of isomeric 1,2,4-benzenetricarboxylic acid monoethylesters following a novel “one-pot” procedure. The polymerization was performed in 1-methyl-2-pyrrolidone/LiCl solutions using triphenylphosphite and pyridine as condensing agents to form amide bonds. Cyclization of the intermediate poly(amide-amic ethylester) occurred by eliminating ethanol under the polymerization conditions used, thus leading to the formation of imide rings. The influence of several parameters which regulate the degree of polymerization and the formation of the imide rings, such as reaction temperature, triphenylphosphite/monomers molar ratio, and pyridine concentration was carefully investigated. In particular, the catalytic activity of pyridine in the imidization reaction has been demonstrated. ¹³C-NMR spectroscopy has been used to show the absence of constitutional regularity in the prepared PAIs thus indicating equal reactivity toward polycondensation of the two different carboxyl groups of the 1,2,4-benzenetricarboxylic acid monoethylesters. © 1996 John Wiley & Sons, Inc.     

Novel method for preparation of poly(benzoxazinone‐imide)

A novel method was developed to prepare poly(benzoxazinone‐imide) by the dealcoholization of poly(amide‐imide), having pendent ethoxycarbonyl groups, which was prepared from poly(amide acid). The poly(amide acid) was prepared from the reaction of pyromellitic dianhydride and 4,4′‐diamino‐6‐ethoxycarbonyl benzanilide. The curing behavior of the poly(amide acid) was monitored by DSC, which indicated the presence of two broad endotherms, one with maximum at 153 °C due to imide‐ring formation and the other with maximum at 359 °C due to benzoxazinone‐ring formation. The poly(amide acid) was thermally treated at 300 °C/1 h to get poly(amide‐imide) with pendent ester groups, then at 350 °C/2 h to convert into poly(benzoxazinone‐imide) by dealcoholization. Viscoelastic measurements of the poly(amide‐imide) showed that the storage modulus dropped at about 280 °C with glass‐transition temperature (T_g ) at about 340 °C. The storage modulus of poly(benzoxazinone‐imide), however, was almost constant up to 400 °C and no T_g was detected below 400 °C. Also, the tensile modulus and tensile strength of the poly(benzoxazinone‐imide) was much higher than that of the poly(amide‐imide). The 5% decomposition of poly(benzoxazinone‐imide) film was at 535 °C, which reflects its excellent thermal stability. Also, poly(benzoxazinone‐imide) showed more hydrolytic stability against alkali in comparison to polyimides. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1647–1655, 2000     

Peculiarities of Formation of Intermolecular Polycomplexes Based on Polyacrylamide,Poly(vinyl alcohol) and Poly(ethylene oxide)

The phenomenon of self-assembly of aggregates formed by relatively short chains of poly(vinyl alcohol) (PVA) on the long macromolecules of polyacrylamide (PAA) in aqueous medium are discussed. PVA and PAA form intermolecular polycomplexes (InterPC) of a constant composition independently on a ratio of polymer components. The complex formation between high-molecular-weight PAA and relatively low-molecular-weight poly(ethylene oxide) (PEO) are considered also. PEO with M ⩽ 4·10⁴ g.mol⁻¹ weakly interacts with PAA. The polymer-polymer interaction can be intensified when the part of amide groups (∼20 mol %) on PAA chain to transform into the carboxylic groups. InterPCs formed by PEO and initial or modified PAA have associative structure with friable packing of the polymer segments. They are stabilized by the hydrogen bond system.     

Ring formation on heating poly(methyl vinyl ether-alt-ammonium maleamate)

Poly(methyl vinyl ether-alt-ammonium maleamate), when heated at up to 100°C while removing volatiles, is converted to polymer whose infrared, elemental analysis and T_g are consistent with a structure predominantly that of poly(methyl vinyl ether-alt-maleic anhydride). Maleimide comonomer units are a substantially lesser component. Evidence is presented that a part of the reaction sequence may involve hydrolysis of imide or amide.     

Thermal imidization and structural evolution of thin films of poly(4,4'-oxydiphenylene p-pyromellitamic diethyl ester)

The evolution of chemical composition and structure during the thermal imidization of an ester-type polyimide precursor, poly(4,4'-oxydiphenylene p-pyromellitamic diethyl ester), in micrometer scale films were studied for a heating rate of 2.0 degrees C/min with time-resolved synchrotron X-ray diffraction, in-situ infrared spectroscopy, and modulated differential scanning calorimetry. Our analyses show that the precursor polymer undergoes imidization in a two-step process. In the first step, the precursor polymer is decomplexed from the residual solvent molecules, and in the second step, it undergoes imide ring formation with the release of ethanol as a byproduct. The imidization reaction starts around 210 degrees C and continues up to 320 degrees C. The thermal imidization reaction induces the structural evolution of the film. As the imidization reaction proceeds, the coherent length along the polymer chain axis increases. This imidization-induced structural evolution was found to occur via three steps: (i) initiation, (ii) the first crystallization, and (iii) the second crystallization. The initiation step is necessary prior to the evolution of the crystalline structure to increase the chain mobility of the precursor polymer chains, and it requires thermal heating up to at least 238 degrees C at which point 22.5% of the imidization is complete. Thereafter, the first crystallization occurs up to 310 degrees C, at which point 98.3% of the imidization is complete. In the range 310-380 degrees C, the second crystallization occurs and produces almost complete imidization of the polymer chains.     

Some Aspects of the Reaction of Polyacrylamide with Formaldehyde

The reaction of polyacrylamide with formaldehyde was studied in a neutral aqueous medium at equal initial molar concentrations of amide groups and of formaldehyde (0.05 mol/L) and in a range of temperatures from 45 to 75°C. The process was investigated by measuring the loss of free formaldehyde in the reaction mixture and the changes of the sum of free formaldehyde and methylol groups versus time. The addition of HCHO to an amide function of the polymer leads to its N-methylol derivative which may transform into the product of condensation between the latter and another amide group. Because of high dilution of polyacrylamide macromolecules in the reaction mixtures studied, cross-linking of the polymer chains with formaldehyde is rather unlikely. Therefore the disappearance of the N-methylols formed is probably due to some intramolecular reactions. It is believed that they involve the condensation of N-hydroxymethyls with neighboring amide groups which results in cyclic structures containing methylenediamide sequences. The occurrence of intramolecular reactions was confirmed by applying Flory's theory of gelation. The addition of HCHO to amide functions is a rate-determining stage in the case of polyacrylamide. For this reaction the rate constants were estimated and the corresponding activation energy was found to be 62 kJ/mol.     

Thermochemical reactions in polycomplexes

Polycomplex formation between poly(methacrylic acid) and polyacrylamide in aqueous solutions has been studied by means of viscometry, potentionetry and elemental analysis. Stoichiometry of the polycomplex was found to be 1:1 with respect to unit-moles. I.R.-spectroscopic data give evidence of the co-existence of ladder-like regions and loops in the polycomplexes formed by poly(methacrylic acid) with polyacrylamide and poly(ethylene glycol). The reactivities of the same functional groups in ladder-like regions and loops are different. This difference has been shown taking as an example thermochemical reactions in the above polycomplexes. Dehydrocyclization in the poly(methacrylic acid) chain was found to occur in the loops of both polycomplexes. This intramolecular reaction in the polycomplex of poly(methacrylic acid) with polyacrylamide is followed by intermolecular formation of imide bonds in ladder-like regions.     

Coordination power adjustment of surface-regulating polymers for shaping gold polyhedral nanocrystals

PVP (poly(vinyl pyrrolidone)) is a common polymer that behaves as a surface-regulating agent that shapes metal nanocrystals in the polyol process. We have used different polymers containing tertiary amide groups, namely PVCL (poly(vinyl caprolactam)) and PDMAm (poly(N,N-dimethyl acrylamide)), for the synthesis of gold polyhedrons, including octahedrons, cuboctahedrons, cubes, and higher polygons, under the present polyol reaction conditions. The basicity and surface coordination power of the polymers are in the order of PVCL, PVP, and PDMAm. A correlation is observed between the coordination power of the polymers and the resulting gold nanocrystal size. Strong coordination and electron donation from the polymer functional groups to the gold surface restrict particle growth rates, which leads to small nanocrystals. The use of PVCL can yield gold polyhedral structures with small sizes, which cannot be achieved in the reactions with PVP. Simultaneous hydrolysis of the amide group in PDMAm leads to carboxylate functionality, which is very useful for generating chemical and bioconjugates through the formation of ester and amide bonds.     

Synthesis and characterization of poly(aryl amide imide)s derived from diphenyltrimellitic anhydride

The synthesis and characterization of a series of novel poly(aryl amide imide)s based on diphenyltrimellitic anhydride are described. The poly(aryl amide imide)s, having inherent viscosities of 0.39–1.43 dL/g in N-methyl-2-pyrrolidinone at 30°C, were prepared by polymerization with aromatic diamines in N,N-dimethylacetamide and subsequent chemical imidization. All the polymers were amorphous, readily soluble in aprotic polar solvents such as DMAC, NMP, dimethylsulfoxide, N,N-dimethylformamide, and m-cresol, and could be cast to form flexible and tough films. The glass transition temperatures were in the range of 284–366°C, and the temperatures for 5% weight loss in nitrogen were above 468°C. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4541–4545, 1999     

Stability of styrene–maleamic acid interpolymers

The response to heat and water of copoly(styrene–maleamic acid, ammonium salt), prepared by treatment with ammonia of the anhydride polymer in toluene suspension, is described. This polymer except for the ammonia bound by salt formation, is stable to heat within the range studied, i.e., to 100°C. The behavior of water solution is determined by the ammonia concentration. Above pH 9, the bound nitrogen remains as amide. If the pH is low, i.e., about 5, as occurs when a dried sample is dissolved in water, then rapid imidization occurs with concurrent hydrolysis. In the early stages of this conversion, imidization occurs mainly through loss of ammonia. This requires that two amide groups be adjacent. Classical imidization by loss of water also occurs, indicating that the normal-amic acid structure is also present.     

Thermal stability of the silica-aminopropylsilane-polyimide interface

Thermal degradation of the silica–aminopropylsilane–amic acid/imide interface was studied by modifying a high-surface-area, neutral silica gel with a number of substituted aminopropylsilanes (APS). These substrates were reacted further with phthalic anhydride or aromatic amic acid monomers and the thermal decomposition of the adsorbed/reacted materials was monitored by thermogravimetric analysis (TGA) and infrared (IR) spectroscopy. The 3-aminopropyltriethoxysilane/poly[N,N′-(p,p′-oxydiphenylene)pyromellitimide] interface was also evaluated by this method. Comparison clearly distinguishes the thermal decomposition of surface-bound APS from surface-bound alkylphthalimides, the adhesion product of alkylamines and aromatic amic acids. Alkylamine imidization with the elimination of aromatic amine (analogous to polymer scission) and the decomposition of the surface-bound imide are shown in the amic acid TGA profiles. This imidization and the accompanying aniline elimination begin at about 130°C, under nitrogen, to form the surface alkyl imide which slowly decomposes at 400°C. TGA analysis indicates that the surface-bound imide undergoes minimal degradation under nitrogen at 370 ± 10°C; temperatures above this threshold range produce changes in the APS–imide interface.     

TFAA chemical derivatization and XPS. Analysis of OH and NHx polymers

The determination of functional groups on complex polymer surfaces by X‐ray photoelectron spectroscopy (XPS) can be improved considerably by derivatization reactions. Simple polymers containing hydroxyl groups or amino groups were investigated as reference materials for the derivatization with trifluoroacetic anhydride (TFAA). ‐1 Poly(vinyl alcohol) (PVA), poly(hydroxyethyl methacrylate) (PHEMA), poly(vinyl butyral) (PVB), poly(allylamine) (PAAm), and poly(diallyl amine) (PDAAm) were derivatized using TFAA and analyzed with XPS. Polyethylene (PE) was used as an independent external reference for the binding energy (BE). Applying this procedure, the BE scales of all measurements were referenced to the carbon atoms of PE. It was found that the BE of the CF₃ component in the C1s region is different when bonded as an acetate or as an amide. The CF₃ BE is also influenced by the density of these groups in the polymer molecule. In TFAA‐PVA, where every second main chain carbon atom carries a trifluoroacetate (TFAc) group, the BE is 294.3 eV while in TFAA‐PVB with only isolated groups, the BE is 293.6 eV. The BE of the CF₃ component in the trifluoroacetamides (TFAAms) prepared from PAAm and PDAAm was found to be 292.5 and 292.3 eV, respectively. Compared with the analog fluorine free compounds, the BE is shifted toward higher values also for the ester carbon atom, the amide carbon atom, and the carbon atom to which the ester or amide is bonded. The data suggest that the gas phase reaction of TFAA with a polymer surface is diffusion limited. The actual ester or amide formation is a fast reaction and runs as a wave into the surface. Copyright © 2009 John Wiley & Sons, Ltd.     

Reaction of poly(vinyl chloride) with superoxide anion

Reaction of poly(vinyl chloride) (PVC) with superoxide anion was carried out in tetrahydrofuran (THF) at 40°C in a nitrogen atmosphere. Remarkable changes in infrared (IR) spectra of the samples treated with superoxide anion were observed in the following regions: ca. 3300, 1680, 1620, and 765 cm^?1, which suggested the formation of hydroxyl groups, α,β-unsaturated ketone groups, and ethylenic structures. Ultraviolet–visible spectra also showed the formation of polyene structures. The content of chlorine in the polymer decreased and that of oxygen increased with reaction time. The reaction mechanism was discussed on the basis of these results.     

Dispersity and stability of foams obtained from poly(vinyl alcohol) solution and the properties of resulting foamed cryogels

Foams have been generated from aqueous poly(vinyl alcohol) solution by two different methods: dispersion (mechanical) method, i.e., by bubbling a gas through a porous medium into the aqueous poly(vinyl alcohol) solution, and the condensation (chemical) method, i.e., by performing a gas-generating reaction directly in the polymer solution. The effect of the formation method on foam stability and dispersity has been studied. The foam produced by the condensation method of foaming the aqueous poly(vinyl alcohol) solution with nitrogen is more stable and finely dispersed and has a higher expansion ratio than that obtained by bubbling the gas through the polymer solution. Foamed cryogels have been formed by freezing-thawing the foam resulting from the chemical reaction in the polymer solution. The values of the elasticity modulus, melting temperature, and thermal conductivity of the cryogels have been determined.     

Polymerization in liquid ammonia: Acrylate esters and vinyl thiolacetate

Methyl ethyl and n-propyl acrylates when polymerized by sodium in liquid ammonia, contain an average of one amino group per polymer chain, which is indicative of amide anion initiation and chain transfer to the solvent ammonia. Isopropyl acrylate and the higher homologs contain considerably less nitrogen than required by one amino group per chain indicative of another initiating and terminating mechanism. Three alternate mechanisms are discussed. Of these, alkoxide initiation seems to be the most plausible. Vinyl thiolacetate polymers prepared under the same conditions also contain less nitrogen than required by one amino group per chain. The polymer structure is predominantly poly(vinyl thiol) with intramolecular or intermolecular disulfide bridges. The acetate part of the molecule is concomitantly split off to form acetamide.     

Preparation and properties of new poly(amide‐imide)s based on 1,4‐bis(4‐trimellitimidophenoxy)naphthalene and aromatic diamines

A diimide dicarboxylic acid, 1,4‐bis(4‐trimellitimidophenoxy)naphthalene (1,4‐BTMPN), was prepared by condensation of 1,4‐bis(4‐aminophenoxy)naphthalene and trimellitic anhydride at a 1 : 2 molar ratio. A series of novel poly(amide‐imide)s (IIa–k) with inherent viscosities of 0.72 to 1.59 dL/g were prepared by triphenyl phosphite‐activated polycondensation from the diimide‐diacid 1,4‐BTMPN with various aromatic diamines (Ia–k) in a medium consisting of N‐methyl‐2‐pyrrolidinone (NMP), pyridine, and calcium chloride. The poly(amide‐imide)s showed good solubility in NMP, N,N‐dimethylacetamide, and N,N‐dimethylformamide. The thermal properties of the obtained poly(amide‐imide)s were examined with differential scanning calorimetry and thermogravimetry analysis. The synthesized poly(amide‐imide)s possessed glass‐transition temperatures in the range of 215 to 263°C. The poly(amide‐imide)s exhibited excellent thermal stabilities and had 10% weight losses at temperatures in the range of 538 to 569°C under a nitrogen atmosphere. A comparative study of some corresponding poly(amide‐imide)s also is presented. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1–8, 2000     

Synthesis and characterization of novel heat resistant poly(amide imide)s

A series of new poly(amide imide)s was prepared from new diacid containing sulfone, ether, amide and imide groups with various aromatic diamines. The diacid was synthesized via four steps, starting from reaction of 4-aminophenol with 4-nitrobenzoyl chloride in the presence of propylene oxide afforded N-(4-hydroxy phenyl)-4-nitrobenzamide. In the second step, reduction of nitro group resulted in preparation of 4-amino-N-(4-hydroxy phenyl) benzamide. In the next step for the preparation of diamine, the reaction of 4-amino-N-(4-hydroxy phenyl) benzamide with bis-(4-chlorophenyl) sulfone in the presence of K₂CO₃ was achieved. The prepared sulfone ether amide diamine was reacted with two moles of trimellitic anhydride to synthesize related sulfone ether amide imide diacid. The precursors and final monomer were characterized by FT-IR, H-NMR and elemental analysis. Direct polycondensation reaction of the sulfone ether amide imide diacid with different diamines in the presence of triphenyl phosphite afforded five different poly (sulfone ether amide imide amide)s. The obtained polymers were fully characterized and their physical properties including thermal behavior, thermal stability, solubility, and inherent viscosity were studied.     

Solid‐state amidization and imidization reactions in vapor‐deposited poly(amic acid)

The condensation polymerization of 4,4′‐oxydianiline with pyromellitic dianhydride for the formation of poly(amic acid) and the subsequent imidization for the formation of polyimides were investigated for films prepared with vapor‐deposition polymerization techniques. Fourier transform infrared spectroscopy, thermal analysis, and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry of films at different temperatures indicated that additional solid‐state polymerization occurred before imidization. The experiments revealed that, upon vapor deposition, poly(amic acid) oligomers formed that had a number‐average molecular weight of about 1500 Da. Between 100–130 °C, these chains underwent an additional condensation reaction and formed slightly higher molecular weight oligomers. Calorimetry measurements showed that this reaction was exothermic [enthalpy of reaction (ΔH) ～ ?30 J/g] and had an activation energy of about 120 kJ/mol. The experimental ΔH values were compared with results from ab initio molecular modeling calculations to estimate the number of amide groups formed. At higher temperatures (150–300 °C), the imidization of amide linkages occurred as an endothermic reaction (ΔH ～ +120 J/g) with an activation energy of about 130 kJ/mol. The solid‐state kinetics depended on the reaction conversion as well as the processing conditions used to deposit the films. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5999–6010, 2004     

Reaction of aluminium chloride with poly(divinyl benzene) particles--a reaction kinetic study using infrared spectroscopy

Porous poly(para-divinylbenzene) and poly(meta-divinylbenzene) particles were synthesised from para-divinylbenzene and meta-divinylbenzene monomers with toluene and 2-ethylhexanoic acid as porogens. The residual vinyl groups in the particles were thereafter reacted using aluminium chloride with dichlorobenzene as a catalyst. The conversion of vinyl groups was followed by analysing polymer particles taken from the reaction mixture at different time intervals. Infrared spectroscopy both in the mid and near infrared region was used as the analytical technique. The intensity changes in the overtone absorption at 1628 nm due to the vinyl bonds were used as the basis for the quantification of the vinyl group consumption. Infrared spectra of the particles in the mid IR were also measured to understand changes taking place in the polymer matrix during the reaction. The results indicated that residual vinyl groups in these polymer particles were consumed during the reaction with aluminium chloride. The reaction of aluminium chloride with the polymer matrix was explained by proposing mechanisms for the formation of different products during the reaction. The complex formed between aluminium chloride and the residual vinyl groups seemed to induce addition of HCl to the vinyl group or leads to crosslinking and/or cyclisation in the case poly(para-DVB) particles. The reaction of aluminium chloride with poly(meta-DVB) takes place to a lesser extent.