A new method for the synthesis of reactive oligoimides with terminal nadic groups without the use of toxic reagents is proposed. The synthesis of ROI is carried out in dimethylacetamide (DMAA) in two stages without isolation of an intermediate product. Aromatic diamine is condensed in the first stage with the mixture of aromatic dianhydride and nadic anhydride at 25 °C to form oligoamidoacid. Thermochemical imidization of oligoamidoacid is carried out in the second stage in the presence of a cyclizing system of methyltriethoxysilane and diazobicyclooctane (MTEOS—DABCO) at 140 °C with the formation of oligoimides carrying terminal nadic groups. The structure of the final products was confirmed by 1H NMR and IR spectroscopy. Bis-amidoacid 2a was obtained as an example of a model compound by condensation of 2,2-bis(4-aminophenoxyphenyl)-propane and nadic anhydride (1: 2 mol) and the kinetics of imidization was investigated. It is demonstrated that the imidization reaction is significantly accelerated in the presence of the MTEOS + DABCO system compared to the reaction in the absence of additives. Almost complete conversion of carboxyamide groups into imide cycles is achieved in 30 min, while maintaining unsaturated bonds in the terminal groups.

A kinetic analysis of the process aimed at preparing soluble polyimide by the thermal imidization of a prepolymer, polyamic acid (PAA), in a dimethylacetamide solution in a temperature range of 120–160 °C was carried out. The scheme including elementary reactions of imidization, synthesis, and decomposition of PAA, as well as the reversible side reaction of hydrolysis of anhydride groups with water released during imidization was used in the analysis. The PAA was synthesized by the low-temperature polycondensation of 2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA) and 2,2-bis(4-aminophenoxyphenyl)propane (BAPP). The rate constants of hydrolysis of anhydride groups and dehydration of phthalic acid fragments were determined experimentally for model compounds: phthalic anhydride and phthalic acid. The experimentally found rate constants of elementary reactions of imidization, decay, and synthesis of PAA of the same chemical structure and in the same temperature range determined by the authors earlier were also used in the calculations. The solution of the system of kinetic equations was performed by the numerical integration using the Maple 17 software. The developed model makes it possible to calculate the dependence of the change in the number average molecular weight of the formed polyimide. According to the calculation results, the initial PAA concentration affects the character of the dependence: the higher the initial concentration of PAA, the more noticeable the role of the side reaction of hydrolysis of terminal anhydride groups, which reduces the rate of increasing average degree of polymerization.

The method of one-stage catalytic polycyclocondensation according to the B4 + AB scheme was used to synthesize new tetraarm star-shaped oligoimides (SOIs) with terminal amino groups and a variable average arm’s length. A new tetraamine obtained by condensation of m -phenylenediamine with a di-Boc derivative of 3,5-diaminobenzoic acid was used as a branching center (B4). 4-(3-Aminophenoxy)phthalic acid was used as the AB heteromonomer. The end amino groups were converted into carboxyl groups by treatment of the resulting reaction SOIs with trimellitic anhydride. The subsequent grafting of an oligoalkylene oxide oligomer with a terminal amino group onto them yielded the stars with block copolymer arms. The chemical and morphological structure of new block copolymer stars has been studied by IR and 1 H NMR spectroscopies, TGA and SEM. It was established by the SEM method that the synthesized objects have a two-phase morphology.

Kinetic regularities of the synthesis of soluble polyimide by cyclization of polyamic acid in solution are investigated. The effective rate constants for the reactions of decomposition and imidization of polyamic acid occurring during imidization are determined depending on temperature. It is demonstrated that the negative deviation of the kinetics of the imidization of polyamic acid in solution from the first-order reaction equation is basically due to the influence of the polyamic acid decomposition with the formation of terminal amino groups.

Published data on the synthesis, structure, and use of polyimides with branched structure, namely, highly branched, hyperbranched, star-shaped, and dendrimers, are reviewed. A special section addresses the synthesis of highly branched and star-shaped polyimides by one-step high-temperature catalytic polycyclocondensation.

By the method of one-stage high-temperature polycondensation of 1,4-phenylene-bis-(5-oxy-1,3-phenylenediamine) (B4 monomer) with 4-(3-aminophenoxy)phthalic acid (AB monomer) in molten benzoic acid, four-arm star-shaped oligoimides with terminal amino groups were synthesized. Oligomers have a narrow molecular weight distribution ( D = 1.2–1.3) and are soluble in organic solvents. The star-shaped oligoimides with terminal acetamide fragments were obtained by acylation of terminal amino groups with acetic anhydride.

ABSTRACTSeries of star‐shaped three arms oligoimides (SOI) with terminal amino groups with narrow MWD ((Mw/Mn = 1.1–2) was synthesized by the one‐stage high‐temperature polycondensation in molten benzoic acid at 140 °C. The (B3+AB′) approach with the “slow addition of monomer” method was used for this synthesis, where B3 is 2,4,6‐tris(4‐aminophenoxy)toluene and AB′ is 3‐aminophenoxy phthalic acid. The SOI arm's length was controlled by the AB′/B3 mole ratio of 10:1, 20:1, 40:1, and 100:1. By the reaction of SOI's terminal amino groups with acetic anhydride, corresponding acetamide derivatives were obtained. SOI synthesized are soluble in selected organic solvents. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 2004–2009

High-temperature thermoplastic semicrystalline polyamide imide (PAI) with Tg = 250°C, and Tm = 370°C was synthesized from 4,4’-diaminobenzanilide, and 2,2-propylidene-bis (1,4-phenyleneoxy) diphthalic anhydride using three different methods: one-pot high-temperature catalytic polycondensation in molten benzoic acid (BA), low-temperature polycondensation (LTP) in dimethylacetamide (DMAA) followed by chemical imidization, and LTP followed by imidization. The influence of the synthetic route on the crystallinity of PAI was studied by wide-angle X-ray scattering. The PAI synthesized in molten BA comprised a reactive oligomer, which on heating up to 360°C easily transformed into high-molecular-weight PAI. The thermal and rheological properties of the high-molecular-weight PAI thus prepared were studied using differential scanning calorimetry, trimellitic acid, thermogravimetric analysis, and capillary viscosimetry. The rheological characteristics indicate that the obtained PAI can be melt processed by extrusion and hot pressing at 370–380°C.

New tetraamine monomer bis(2,3‐diaminophenoxy)benzene (BDAPB) was synthesized by reducing corresponding precursor bis(2,3‐dinitrophenoxy)benzene with hydrazine hydrate. Hyperbranched polyimide with terminal amino groups was synthesized by means of the one‐stage high temperature polycondensation of BDAPB with 2,2‐propylidene‐(1,4‐phenyleneoxy)diphthalic acid in catalytically active solvent – molten benzoic acid at 140°C by the scheme A2+B4. Examples of polymer‐analog transformations were shown of terminal amino groups to form acetamide and phthalimide derivatives.

High-resolution 13C NMR spectroscopy was applied to study the chain microstructure of copolyimides obtained at 140 °C by one-pot high-temperature polycondensation in molten benzoic acid from 2,2-propylidene-bis(4-phenylene-4´-oxyphthalic acid) dianhydride (DA, intermonomer) and two comonomers, 1,3-bis(2-aminoethyl)adamantane (ADA) and 9,9-bis(4aminophenyl)fluorene, varying the order of introduction of components into the system. The experimentally found value of chain microheterogeneity coefficient determined from the 13C NMR data is in a good agreement with the values theoretically calculated using the mathematical model developed earlier by the authors and the kinetic data for the model reactions of acylation of amino groups and imidization of amido acid fragments. An ADA—DA-2,2-hexafluoropropylidene-bis(phthalic acid) dianhydride system provides another example of the principal possibility of varying orders of introduction of components to control the chain microstructure of copolyimides.

Two series of high-molecular-weight copolyimides CPI-1 and CPI-2 containing five-membered imide cycles have been prepared by high-temperature polycondensation in molten benzoic acid (BA) at 140°C from a pair of aromatic/aliphatic diamines (9,9-bis(4-amino)fluorene (AFL) and 1,12-dodecamethylene diamine (DDA)) and one dianhydride (4,4′-oxydiphthalic anhydride (in CPI-1 series) or (1,3-phenylene)-bis(4-oxyphtalic anhydride) (in CPI-2 series)) using different order of the components loading. The diamines moiety distribution in chain was analyzed by means of high resolution carbon nuclear magnetic resonance. It is found that CPI-1 and CPI-2 samples prepared using one-shot comonomers/intermonomer loading have random moieties distribution, whereas the samples prepared using stepwise addition of dianhydride to the mixture of two diamines have multiblock (MB) chain microstructure. Thus, despite complicated scheme of CPIs synthesis in molten BA including several reactions, the process as a whole displays a feature typical for ideal one-stage interbipolycondensation of symmetrical components with independent groups. The average block length increases when DDA and dianhydride are added together slowly to AFL solution in molten BA. The phase morphology of CPI-2 was studied by means of differential scanning calorimeter. The data obtained demonstrate symptoms of microphase separation in nascent powders of MB CPI-2.

A new three-arm reactive oligomer (A3) with three end anhydride groups is prepared via the high-temperature cyclocondensation of 1,3,5-triaminotoluene disulfate with excess 2,2-propylidene-bis(phenyl-4-oxyphthalic acid) dianhydride in molten benzoic acid at 140°C in the presence of [2.2.2]-diazobicyclooctane. A branched polyimide is synthesized via the one-step high-temperature catalytic polycondensation of oligomer A3 with 9,9-bis(4-aminophenyl)fluorene in benzoic acid at 140°C via scheme (A3 + B2) and characterized.

Was indicated that in the photoinitiated controlled polymerization of vinyl acetate in the presence of the complex Co (III) upon irradiation at wavelengths shorter than 320 nm proceeds adverse reaction radicals formation from the polymer.

Brief review of the modern state in the field of thermally stable thermoset resins used as binders for engineering polymer composites in presented. Synthesis, processing, properties, and application of such materials are discussed. The list of binders includes polyimide PMR resins, oligoimides with reactive end groups, bismaleimides, and phthalonitrile resins.

The specific interaction of aromatic and aliphatic diamines with benzoic acid without a solvent was studied by IR spectroscopy and phase diagram analysis.

The specific interaction of aromatic and aliphatic diamines with benzoic acid without a solvent was studied by IR spectroscopy and phase diagram analysis.