Konstitutionsisomerie in Polykondensaten. Teil VI. Synthese und Eigenschaften von völlig geordneten und ungeordneten Bipolyamiden aus <i>cis</i>‐2,6‐Dimethylpiperazin und 1,2,5‐Thiadiazol‐3,4‐dicarbonyl‐dichlorid

Mühlebach, Andreas; Pino, P.

doi:10.1002/hlca.19900730409

Cited by 3 publications

(2 citation statements)

References 11 publications

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“…Secondly, the disorder in our systems is controlled and variable. The constitutional isomerism is determined by the conditions applied during the polymerization process 25,26,37,38,58,[60][61][62][63][64][65][66][67][68][69][70] . The chains spun here are of random constitution 37,38) .…”

Section: Heat Treatment and Fiber Structurementioning

confidence: 99%

An investigation of novel approaches in order to provide crosslinked fully aromatic polyamide chains

Glomm¹,

Oertli²,

Rickert³

et al. 2000

Macromol. Chem. Phys.

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Two different, novel approaches to crosslink fully aromatic, rigid‐rod aramid chains were studied. First, the new rigid‐rod aramid poly[1,4‐phenylen‐2,5‐bis(prop‐2‐ynyloxy)‐terephthalamide] with an inherent viscosity of ηinh = 2.74 dL/g was synthesized by low temperature polycondensation of p‐phenylendiamine and 2,5‐bis(prop‐2‐ynyloxy)‐terephthaloylchloride. The pendant alkinyl moieties allowed thermally induced crosslinking at temperatures higher than 200°C. No weight loss was found due to this treatment, but curing gave rise to the formation of stable radicals. However, no fiber spinning experiments were carried out using this material due to the insufficient stability of the polymer chains against degradation when being dissolved in sulfuric acid. Furthermore, fibers of a rigid rod polyamide containing pyrimidine moieties, produced by polycondensation of bis‐silylated 2,5‐diaminoprimidine and terephthaloyl dichloride, were spun from nematic solutions. Fibers were crosslinked by complexation with nickel(II)‐ions in the swollen state. Both crosslinked and non‐crosslinked, otherwise identically processed samples, were characterized by wide‐angle X‐ray‐diffraction (WAXD) measurements and mechanical tests. A post‐spin heat treatment was employed to improve the low degrees of orientation and crystallinity that the untreated fibers in general showed. The dominating crystal structures of both fiber samples are similar to “Modification II” of the well characterized fibers from poly(p‐phenylene‐terephthalamide) (PPTA). The number and size of the morphological defects in the crosslinked fibers was significantly higher than in the non‐crosslinked samples. The influence of the annealing on the mechanical fiber properties and the molecular order in the fibers was investigated. The values of all mechanical parameters were considerably lower in the case of the crosslinked fibers, probably due to the collapse of the entire supramolecular order and fiber morphology.

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Section: Heat Treatment and Fiber Structurementioning

confidence: 99%

An investigation of novel approaches in order to provide crosslinked fully aromatic polyamide chains

Glomm¹,

Oertli²,

Rickert³

et al. 2000

Macromol. Chem. Phys.

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“…In case the two monomers have structures of XabX and YccY, where X and Y are the functional groups participating in polymerization, there should arise head‐to‐head (HH), or –(abccbacc) n –, head‐to‐tail (HT), or –(abccabcc) n –, and a random polymer having no regularity for the direction of the –ab– unit in the main chain. Concerning this, Pino and coworkers first reported on the synthesis of a set of HH, HT, and random polyamides having common repeating units 2–4. In one case, the isomeric polyamides showed significantly different gas separation behaviors between hydrogen and methane.…”

Section: Introductionmentioning

confidence: 99%

Constitutionally isomeric alicyclic polyimides: Origin of siteselectivity in the reaction of unsymmetrical dianhydride and structure‐derived difference in physical properties

Choi

Shirai

Takayama

et al. 2012

J. Polym. Sci. A Polym. Chem.

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Two constitutionally isomeric alicyclic polyimides (PIs), head-to-head (HH) and random types, were successfully synthesized on the basis of a siteselective ring opening reaction of an unsymmetric spiroalicyclic dianhydride, rel-[1R,5S,6R]-3-oxabicyclo[3,2,1]octane-2,4-dione-6-spiro-3 0 -(tetrahydrofuran-2 0 ,5 0 -dione), with using several kinds of diamines only by changing reaction procedures. A model reaction study revealed that the origin of the siteselectivity in the reaction of the dianhydride was due to both the enhanced reactivity of sixmembered anhydride embedded in bicyclo[3.2.1] system and the reduced reactivity of five-membered anhydride in the spiro[4.5] system. The HH-PIs showed higher glass transition temperature and higher dielectric constant than those of random PIs. Specific gravity of the PI films showed that the differences in physical properties stem from different packing density of the two constitutionally isomeric PIs. This is the first example for constitutionally isomeric both amorphous polycondensates with different physical properties. V C 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 50: [4246][4247][4248][4249][4250][4251][4252][4253][4254] 2012

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Spinning and characterization of fibers from poly(2,6‐dichloro‐p‐phenyleneterephthalamide): a study of constitutional isomerism and solid‐state arrangements by comparison between simulation and experiment

Glomm¹,

Küuchenmeister²,

Neuenschwander³

et al. 1994

Macro Chemistry & Physics

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Fibers of three constitutionally isomeric rigid-rod polymers, produced by polycondensation of 2,6-dichloro-p-phenylenediamine and terephthaloyl dichloride, were spun from nematic solutions and characterized by wide-angle X-ray diffraction (WAXD) measurements and mechanical tests. A post-spin heat treatment was employed to improve the low degrees of orientation and crystallinity that the untreated fibers showed. The dominating crystal structure of constitutionally ordered head-to-head/tail-to-tail fibers seems to be very similar to "Modification 11" of the fibers From poly@-phenyleneterephthalamide) (PPTA), but the fibers do not suffer a comparable structural transformation upon heat treatment. Influences of the constitutional regularity in the chains on the crystal structure, structural order and mechanical properties of the fibers could be observed. Both the observed crystal structure and the experimentally determined mechanical properties agree well with the results of detailed atomistic modeling predictions.

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Konstitutionsisomerie in Polykondensaten. Teil VI. Synthese und Eigenschaften von völlig geordneten und ungeordneten Bipolyamiden aus cis‐2,6‐Dimethylpiperazin und 1,2,5‐Thiadiazol‐3,4‐dicarbonyl‐dichlorid

Cited by 3 publications

References 11 publications

An investigation of novel approaches in order to provide crosslinked fully aromatic polyamide chains

An investigation of novel approaches in order to provide crosslinked fully aromatic polyamide chains

Constitutionally isomeric alicyclic polyimides: Origin of siteselectivity in the reaction of unsymmetrical dianhydride and structure‐derived difference in physical properties

Spinning and characterization of fibers from poly(2,6‐dichloro‐p‐phenyleneterephthalamide): a study of constitutional isomerism and solid‐state arrangements by comparison between simulation and experiment

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