Synthesis of aromatic polyimides by two-stage polycyclization of 2,5-dicarbomethoxyterephthaloyl chloride with diamines

Коршак, В.В.; Виноградова, С. В.; Vygodskii, Ya. S.; Gerashchenko, Z.V.

doi:10.1016/0032-3950(71)90344-3

Cited by 20 publications

(6 citation statements)

References 7 publications

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“…Since the reverse propagation reaction does not occur during the thermal imidisation of salts of poly(amic acids) and poly(amic esters), their molecular weights do not change during the heating process [72]. Their mechanical properties simply change from those of the pre-polymer to those of the polyimide.…”

Section: Changes In Mechanical Properties and Molecular Weight Duringmentioning

confidence: 98%

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Synthesis of aromatic polyimides from dianhydrides and diamines

Harris¹

1990

Polyimides

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Section: Changes In Mechanical Properties and Molecular Weight Duringmentioning

confidence: 98%

“…Thus, the reaction can be prevented by removing the carboxylic acid proton prior to imidisation. Amine salts of poly(amic acids) and poly(amic esters) do not regenerate anhydride and amine moieties during their thermal imidisation [72,73].…”

Section: Mechanism Of Thermal Imidisationmentioning

confidence: 99%

Synthesis of aromatic polyimides from dianhydrides and diamines

Harris¹

1990

Polyimides

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“…For several years poly(amic alkyl ester)s [7][8][9][10] and especially poly(amic ethyl ester)s [11][12][13][14][15] have been used as precursors for polyimides. In comparison with poly(amic acid)s, they offer improved solubility, better resistance to hydrolysis, and high molecular weight products but suffer from higher and broader imidization temperatures.…”

Section: Introductionmentioning

confidence: 99%

Preparation of Well-oriented Poly(p-phenylene pyromelliteimide) Fiber via Shear-induced Orientation of Poly(amic ethyl ester) Precursor during Polymerization

Zhuang

Kimura

Xia

et al. 2005

High Performance Polymers

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The orientation of poly ( p-phenylene pyromelliteimide) (PPPI) molecules was examined by means of shearing during the gelation of poly(amic ethyl ester) (PAEE) precursor and thermal imidization. The polymerization of 1,4-phenylene diamine (PPDA) and 2,5-diethoxycarbonyl-1,4-benzenedicarbonyl chloride (DEBC), and that of N, N'-bis(trimethylsilyl)-1,4-phenylenediamine (N-silyl-PPDA) and DEBC yielded the PAEE gel during polymerization. With respect to the polymerization of PPDA and DEBC, 0.44 mol L-1 gave the highest DPn of PAEE at the gelation point, and the strong shear during gelation made the PAEE and ultimately PPPI molecular chains oriented in the planar mode. In contrast to this, the polymerization of N-silyl-PPDA and DEBC gave a higher DPn of PAEE at the gelation point than that of PPDA and DEBC. The strong shear stress applied to the PAEE gel, prepared at 0.50 mol L-1, induced the uni-axial orientation of the molecular chains, but the relaxation of the orientation occurred gradually with time. The addition of ethyl acetate to the gel prevented the relaxation of the chain orientation and accelerated the crystallization. As a result, uni-axial orientation of the PAEE molecular chains was induced along the shear direction in the gel rather than the planar mode, and ultimately the PPPI molecular chains were well-oriented.

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“…[2,3] The imidization step is usually carried out in the solid state as a thermally or chemically induced intramolecular ring closure. Since several years also poly(amic alkyl ester)s (PAE), [4][5][6][7] and especially poly(amic ethyl ester)s developed by Volksen and coworkers are used as precursors. [3,[8][9][10] Compared to PAA precursors, PAEs offer improved solubility, better resistance to hydrolytic degradation, yield high molecular weight products but suffer from higher and broader imidization temperatures.…”

Section: Introductionmentioning

confidence: 99%

“…[3,[8][9][10] Compared to PAA precursors, PAEs offer improved solubility, better resistance to hydrolytic degradation, yield high molecular weight products but suffer from higher and broader imidization temperatures. [4,5] The synthesis of PAEs involves three steps: initially an isomeric mixture of diacid-diesters is formed by reaction of dianhydrides with alcohols (see Figure 1). For simple dianhydrides, such as pyromellitic dianhydride (PMDA), only meta-and para-isomers are formed which can be separated by extraction or recrystallization.…”

Section: Introductionmentioning

confidence: 99%