Synthese und Charakterisierung von cis- und trans-Dicyclohexyl-3,3′,4,4′- tetracarbonsäuren und ihren Dianhydriden / Syntheses and Characterization of cis- and trans-Dicyclohexyl-3,3′,4,4′- tetracarboxylic Acids and their Dianhydrides

Shiotani, Akinori

doi:10.1515/znb-2001-0210

Cited by 1 publication

(6 citation statements)

References 3 publications

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“…The measured T g for the H-BPDA/4,4′-ODA (246 °C by DMA at 0.1 Hz, Table 8 ) was also approximate to that for the cis -DCDA/4,4′-ODA film reported in the literature (259 °C by DSC [ 33 ] and 256 °C by DMA at 1 Hz [ 42 ]). These results do not conflict with the aforementioned prediction, based on the 1 H-NMR spectral similarity, that H-BPDA used in this study has essentially the same steric structure as cis -DCDA [ 33 , 64 ].…”

Section: Resultssupporting

confidence: 74%

“…The crystallization of H-BPDA-based model compounds was unsuccessful. Hence, the steric structure of H-BPDA used in this study was predicted by comparing its spectral data that we measured with those reported in the literature [ 33 , 42 , 64 ].…”

Section: Resultsmentioning

confidence: 99%

“…Shiotani et al [ 33 , 64 ] proved that a single crystal obtained via catalytic hydrogenation of 3,3′,4,4′-biphenyltetracaboxylic acid tetramethyl ester, hydrolysis of the reductant, cyclodehydration, and crystallization has a highly distorted steric structure, i.e., rel -(1R,1′ S ,3R,3′ S ,4S,4′ R )-dicyclohexyl-3,3′,4,4′-tetracarboxylic dianhydride ( cis -DCDA, Figure S4a ). On the other hand, a stereoisomer of cis -DCDA, rel -(1R,1′ S ,3R,3′ S ,4R,4′ S )-dicyclohexyl-3,3′,4,4′-tetracarboxylic dianhydride ( trans -DCDA, Figure S4b ), which has a steric structure with higher planarity and linearity than cis -DCDA, can be obtained by intentionally isomerizing the reductant of the tetramethyl ester.…”

Section: Resultsmentioning

confidence: 99%

“…On the other hand, a stereoisomer of cis -DCDA, rel -(1R,1′ S ,3R,3′ S ,4R,4′ S )-dicyclohexyl-3,3′,4,4′-tetracarboxylic dianhydride ( trans -DCDA, Figure S4b ), which has a steric structure with higher planarity and linearity than cis -DCDA, can be obtained by intentionally isomerizing the reductant of the tetramethyl ester. The cis -DCDA showed a reasonable 1 H-NMR spectrum where the signal of 3,3′-axial protons on the cyclohexane (CH) units were clearly separated from that of the 4,4′-equatorial protons, reflecting their different magnetic environments [ 64 ]. H-BPDA used in the present study also exhibited a very similar 1 H-NMR spectrum with the above-mentioned feature consisting of the 4,4′-equatorial proton signal peak centered at 3.50 ppm (not well resolved) and the 3,3′-axial proton signal centered at 3.13 ppm (not well resolved)], as shown in Figure S5 .…”

Section: Resultsmentioning

confidence: 99%

“…Figure S3: Thermal behavior of C 12 -model: (a) DSC thermograms in the heating and cooling processes, (b) polarizing optical microscope photograph taken at 135.8 °C during the cooling process from 160 °C above the clearing point (139.6 °C), and (c) expected conformations favorable (i) and unfavorable (ii) for liquid-crystal formation. Figure S4: Steric structures of stereoisomers isolated by Shiotani et al [ 33 , 64 ]: (a) rel -(1R,1′ S ,3R,3′ S ,4S,4′ R )-dicyclohexyl-3,3′,4,4′-tetracarboxylic dianhydride ( cis -DCDA) and (b) rel -(1R,1′ S ,3R,3′ S ,4R,4′ S )-dicyclohexyl-3,3′,4,4′-tetracarboxylic dianhydride (trans -DCDA). Figure S5: 1 H-NMR spectrum (DMSO- d 6 ) of H-BPDA used in this study.…”

mentioning

confidence: 99%

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Colorless Polyimides Derived from 5,5′-bis(2,3-norbornanedicarboxylic anhydride): Strategies to Reduce the Linear Coefficients of Thermal Expansion and Improve the Film Toughness

Hasegawa,

Miyama,

Ishii

et al. 2023

Polymers

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In this paper, novel colorless polyimides (PIs) derived from 5,5′-bis(2,3-norbornanedicarboxylic anhydride) (BNBDA) were presented. The results of single-crystal X-ray structural analysis using a BNBDA-based model compound suggested that it had a unique steric structure with high structural linearity. Therefore, BNBDA is expected to afford new colorless PI films with an extremely high glass transition temperature (Tg) and a low linear coefficient of thermal expansion (CTE) when combined with aromatic diamines with rigid and linear structures (typically, 2,2′-bis(trifluoromethyl)benzidine (TFMB)). However, the polyaddition of BNBDA and TFMB did not form a PI precursor with a sufficiently high molecular weight; consequently, the formation of a flexible, free-standing PI film via the two-step process was inhibited because of its brittleness. One-pot polycondensation was also unsuccessful in this system because of precipitation during the reaction, probably owing to the poor solubility of the initially yielded BNBDA/TFMB imide oligomers. The combinations of (1) the structural modification of the BNBDA/TFMB system, (2) the application of a modified one-pot process, in which the conditions of the temperature-rising profile, solvents, azeotropic agent, catalysts, and reactor were refined, and (3) the optimization of the film preparation conditions overcame the trade-off between low CTE and high film toughness and afforded unprecedented PI films with well-balanced properties, simultaneously achieving excellent optical transparency, extremely high Tg, sufficiently high thermal stability, low CTE, high toughness, relatively low water uptake, and excellent solution processability.

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