1989
DOI: 10.1021/ma00194a031
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Synthesis and structure of thermotropic main-chain polyethers based on bis(4-hydroxyphenoxy)-p-xylene

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Cited by 27 publications
(10 citation statements)
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“…The energy minimum conformations (Fig. 6) indicate that molecular linearity and parallelism coupled with a higher aspect ratio are possible for HPPA/HBA copolyester chains, whereas such molecular orientational ordering is not possible for HPAA/HBA copolyesters 24. The birefringence and grainy texture observed in the melt may, however, be attributed to a layered smectic structure similar to that reported by Percec et al19 for polyethers with bend structures 19.…”
Section: Resultssupporting
confidence: 60%
“…The energy minimum conformations (Fig. 6) indicate that molecular linearity and parallelism coupled with a higher aspect ratio are possible for HPPA/HBA copolyester chains, whereas such molecular orientational ordering is not possible for HPAA/HBA copolyesters 24. The birefringence and grainy texture observed in the melt may, however, be attributed to a layered smectic structure similar to that reported by Percec et al19 for polyethers with bend structures 19.…”
Section: Resultssupporting
confidence: 60%
“…The heat of melting (Δ H m ) was smaller than the heat of isotropization (Δ H i ), indicating that the difference in order between the semi‐crystalline state and mesophase is smaller than the difference between the mesophase and the isotropic melt. This result suggests that the mesophase is highly ordered 13. Regarding the thermal stability, all the copolymers had very high 5% weight loss temperatures ( T d 's) ranging from 480 to 520 °C.…”
Section: Resultsmentioning
confidence: 89%
“…To further investigate this observation for an explanation, we investigated the conformational characteristics of the repeat unit, C 6 H 4 CH 2 COOC 6 H 4 CH 2 COOC 6 H 4 , via conformational studies with the Sybyl form field method of PC SPARTAN software. The central question was whether the unit could meet the large aspect ratio, anisotropic molecular polarizability, and rigidity and molecular parallelism (linear macro conformation) for a molecule to constitute a mesogen 21, 22. For polyHPAA, the adjacent phenylene rings are not lying in the same plane to give molecular parallelism as in polyHBA.…”
Section: Resultsmentioning
confidence: 99%