One-pot high-temperature synthesis of polyimides in molten benzoic acid: Kinetics of reactions modeling stages of polycondensation and cyclization

Кузнецов, А. А.; Tsegelskaya, A. Yu.; Buzin, Pavel

doi:10.1134/s0965545x0711003x

Cited by 9 publications

(6 citation statements)

References 4 publications

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“…Since in the real synthesis of CPI the consecutive reactions of acylation and imidization are technologically inseparable and, hence, the direct determination of the corresponding reaction rate constants seems impossible, we used kinetic data obtained by us in model experiments. For series of diamines (Figure 1 and Table 1), the rate constants of acylation with phthalic anhydride in acetic acid (direct and reverse reactions) were measured at moderate temperatures (20-80 C, with the absence of imidization reaction) and extrapolated to 140 C. 26,28 The imidization rate constant for amido acid moiety of model compounds in AcOH at 140 C (in sealed ampoules) was taken from our earlier publication. 24 At 140 C, the constant rates of direct and reverse reactions of acylation stage in molten BA are extremely highdue to molten BA acts as powerful "bifunctional type" catalyst 29 facilitating intermolecular proton transfer which is limiting the elementary stage of reaction.…”

Section: Resultsmentioning

confidence: 99%

Modeling of copolyimide chain microstructure formation in a course of the one-pot copolycondensation in molten benzoic acid

Кузнецов

Batuashvili

Kaminskii

2017

High Performance Polymers

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Mathematical modeling was has been developed for the chain microstructure formation in the synthesis of copolyimides (CPI) by the one-pot high-temperature catalytic polycondensation from two diamines A and B (comonomers) and one dianhydride C (intermonomer) in molten benzoic acid at 140°C accomplished with different regimes of intermonomer loading. The kinetic scheme including the acylation of the amino group of both diamines with the anhydride fragment, decomposition, and imidization of two intermediate amido acid fragments was examined. The kinetic parameters of the acylation and imidization stages necessary for calculations were determined previously in independent experiments. The numerical solution of the system of kinetic equations for different regimes of intermonomer loading gave the calculated dependences of the change in time of the average block length, the current concentrations of amino- and anhydride groups, amido acid fragments (unstable dyads: AC1 and BC1), imide cycles (stable dyads: AC2 and BC2), and triads. The calculated values of the average block length and the chain microheterogeneity parameter ( Km = 0.5) for the first three comonomer pairs at gradual intermonomer loading correspond to the multiblock microstructure of the chain. These values are in good agreement with the experimental values obtained from 13C NMR data for CPI based on the indicated diamines and 2,2-propylidenebis(1,4-phenyleneoxy)diphthalic dianhydride.

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Section: Resultsmentioning

confidence: 99%

Modeling of copolyimide chain microstructure formation in a course of the one-pot copolycondensation in molten benzoic acid

Кузнецов

Batuashvili

Kaminskii

2017

High Performance Polymers

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“…Kinetic data were obtained by potentiometric titration of amino groups with solution of perchloric acid in AcOH after reaching an equilibrium state [16,17]. Results are presented in Table 3 [16,17].…”

Section: Mechanism and Kineticsmentioning

confidence: 99%

“…In Table 4, the values of rate constants at 140°C obtained by extrapolation are given. (4) with phthalic anhydride [16,17].…”

Section: Model Reactions Of Amic Acid Formation and Imidizationmentioning

confidence: 99%

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Synthesis of Polyimides in the Melt of Benzoic Acid

Alexeevich¹,

Yurievna²

2020

Solvents, Ionic Liquids and Solvent Effects

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Review of the authors' works on the synthesis of polyimides (PIs) by the method of one-stage high-temperature polycondensation in an unusual solvent-molten benzoic acid (BA). Compared with a known synthesis in inert high-boiling solvents, synthesis in BA takes place under mild conditions (140°C, 1-2 hour) to give completely imidized PIs. The approach has a number of advantages. Due to catalysis of the first reversible stage of amiс acid (AA) formation and low equilibrium constant (K = 10-20 l/mol), the first stage disappears kinetically, and the imidization reaction becomes limiting. The process becomes less sensitive to the basicity of diamines; therefore, low reactivity diamines can be involved. Water is easily removed from the melt by evaporation, which makes the whole process irreversible. Specific features of the method are successfully used to control the microstructure of the chain copolyimides (statistical to multiblock) and to synthesize hyperbranched PIs and star-shaped PIs with narrow molecular weight distribution.

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“…Kuznetsov et al showed that the synthesis of PIs, including branched PIs, efficiently occurs in the molten benzoic acid, which serves as an active medium during the formation of these types of poly mers [55][56][57][58][59].…”

Section: Polyimides and Polyamidesmentioning

confidence: 99%