Equilibrium short-range order in the isotropic phase of a poly(ester-imide) with a C22H44 alkane spacer

Kwon, Yong Ku; Annis, B. K.; Chen, Wei; Wunderlich, Bernhard

doi:10.1002/(sici)1099-0488(20000215)38:4<611::aid-polb13>3.0.co;2-0

Cited by 2 publications

(3 citation statements)

References 35 publications

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“…The chemical structure for PEIM-22 is given in Figure 1. Calorimetric as well as X-ray data are available for PEIM-22, 58,59 while supporting solid-state NMR information is available PEIM-9 and PEIM-12. 60,61 These precisely segmented PEIMs have a smectic-like layer structure with a coherently scattering stack of 3-4 repeating units, 59 with the methylene sequences being nanophase-separated in a hexagonal condis structure with specific bonds ordered into a trans conformation.…”

Section: Discussionmentioning

confidence: 80%

“…The chemical structure for PEIM-22 is given in Figure . Calorimetric as well as X-ray data are available for PEIM-22, , while supporting solid-state NMR information is available PEIM-9 and PEIM-12. , These precisely segmented PEIMs have a smectic-like layer structure with a coherently scattering stack of 3−4 repeating units, with the methylene sequences being nanophase-separated in a hexagonal condis structure with specific bonds ordered into a trans conformation. , In these and similar segmented macromolecules the two chemically different segments are at the basis of the nanophase separation, driven by the immiscibility of the two sequences. The crystallinity of the CH 2 sequences provide the largest portion of the heat of crystallization and stabilize the overall crystal stacks, which in turn assume the lamellar superstructure .…”

Section: Discussionmentioning

confidence: 89%

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Effect of the Precise Branching of Polyethylene at Each 21st CH₂ Group on Its Phase Transitions, Crystal Structure, and Morphology

et al. 2005

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Three linear polyethylenes with branches at every 21st backbone atom have been analyzed by differential scanning calorimetry (DSC) and quasi-isothermal, temperature-modulated DSC. The branches were methyl (PE1M), dimethyl (PE2M), and ethyl groups (PE1E). Linear polyethylene (HDPE) and atactic poly-(octadecyl acrylate) (PODA) were also analyzed. All were compared to a random poly(ethylene-co-octene-1) of similar branch concentration (LLDPE) and poly(4,4′-phthaloimidobenzoyldoeicosyleneoxycarbonyl) (PEIM-22). The HDPE has the highest melting temperature and crystallinity with relatively large contributions of reversing melting when grown as folded-chain crystals. The precisely branched polyethylenes and copolymers have lower melting temperatures and heats of fusion. Of the branched samples, PE1M crystallizes more readily, followed by PE1E and PE2M, with PE2M showing cold crystallization. In contrast to paraffins of equal length which melt fully reversibly, the precisely designed, branched polymers melt largely irreversibly with small amounts of reversing melting, which is least for the best-grown crystals. The PE1M forms monoclinic, PE1E, pseudohexagonal, or triclinic crystals, and PE2M has a multitude of crystal structures.

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Section: Discussionmentioning

confidence: 80%

Section: Discussionmentioning

confidence: 89%

Effect of the Precise Branching of Polyethylene at Each 21st CH₂ Group on Its Phase Transitions, Crystal Structure, and Morphology

et al. 2005

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“…Second, in the precisely controlled copolymers PE1M and PEIM-22 have a crystalline, lamellar morphology of a thickness of 3-4 layers of repeating units. 7,8 The orthorhombic crystal structure of HDPE was not observed in these copolymers. 1 Instead, all samples have different, paraffin-like lateral packing, such as the frequently discussed hexagonal, monoclinic or triclinic polyethylene and paraffin structures.…”

Section: Introductionmentioning

confidence: 99%

Crystallization and melting of a branched polyethylene with precisely controlled chemical structure

Qiu¹,

Pyda²,

Nowak-Pyda³

et al. 2006

J Polym Sci B Polym Phys

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ABSTRACT:The heat capacity of a linear polyethylene with dimethyl branches, at every 21st backbone atom was analyzed by differential scanning calorimetry (DSC) and quasiisothermal temperature-modulated DSC. This novel copolyethylene (PE2M) is relatively difficult to crystallize from the melt. On subsequent heating, a first, sharp melting peak is followed by a sharp cold-crystallization and crystal perfection and a smaller endotherm, before reaching the main melting at 315-320 K, close to the melting temperatures of eicosane and tetracontane. The low-temperature melting is sensitive to the cooling rate and disappears below 1.0 K min À1 . The cold crystallization can be avoided by heating with rates faster than 80 K min À1 . The PE2M exhibits some reversing and reversible melting, which is typical for chain-folded polymers. The glass transition of semicrystalline PE2M is broadened and reaches its upper limit at about 260 K (midpoint at about 0.355 K). Above this temperature, the crystals seem to have a heat capacity similar to that of the liquid. A hypothesis is that the melting transition can be explained by changes in crystal perfection without major alteration of the crystal structure and the lamellar morphology.

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Equilibrium short-range order in the isotropic phase of a poly(ester-imide) with a C22H44 alkane spacer

Cited by 2 publications

References 35 publications

Effect of the Precise Branching of Polyethylene at Each 21st CH₂ Group on Its Phase Transitions, Crystal Structure, and Morphology

Effect of the Precise Branching of Polyethylene at Each 21st CH₂ Group on Its Phase Transitions, Crystal Structure, and Morphology

Crystallization and melting of a branched polyethylene with precisely controlled chemical structure

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Equilibrium short-range order in the isotropic phase of a poly(ester-imide) with a C22H44 alkane spacer

Cited by 2 publications

References 35 publications

Effect of the Precise Branching of Polyethylene at Each 21st CH2 Group on Its Phase Transitions, Crystal Structure, and Morphology

Effect of the Precise Branching of Polyethylene at Each 21st CH2 Group on Its Phase Transitions, Crystal Structure, and Morphology

Crystallization and melting of a branched polyethylene with precisely controlled chemical structure

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Product

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Effect of the Precise Branching of Polyethylene at Each 21st CH₂ Group on Its Phase Transitions, Crystal Structure, and Morphology

Effect of the Precise Branching of Polyethylene at Each 21st CH₂ Group on Its Phase Transitions, Crystal Structure, and Morphology