Crystal Structures of Isotactic and Atactic Poly(1-pentamethylene alcohol)

Tashiro, Kohji; Guillory, Gina A.; Marxsen, Stephanie F.; Kennemur, Justin G.; Alamo, Rufina G.

doi:10.1021/acs.macromol.3c01060

Cited by 3 publications

(4 citation statements)

References 31 publications

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“…Observed 2D WAXD patterns in comparison with the calculated ones: (a) nylon-6 α form and (b) nylon-6 iodine complex II. It is noted that the calculated meridional diffraction peaks are relatively weaker in intensity compared with the observed ones, being originated from the crossing of the reciprocal lattice points (00 l ) with the Ewald sphere (see refs and ).…”

Section: Resultsmentioning

confidence: 99%

Crystal Structures of Nylon–Iodine Complexes

Tashiro,

Gakhutishvili,

Takahama

2024

Macromolecules

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The crystal structures of iodine complexes of nylon-6 and nylon-66 samples were proposed on the basis of 2-dimensional wide-angle X-ray diffraction data analysis combined with the observed polarized Raman spectral data and the density functional theoretical calculations. As reported in our previous paper (Macromolecules, 2024(Macromolecules, , 57, 2260, the skeletal chains of nylon were found to be contracted about 5% from the fully extended conformations, which are caused by the trans-to-skew torsional angle change around CH 2 −amide bonds so that the charge transfer occurs from the iodine ion to N−H group. The iodine ion rods are sandwiched between the nylon chains alternately. The I 5 − and I 3 − ion rods are oriented, respectively, along the nylon chain axis and in the direction approximately perpendicular to the chain axis. The sandwich packing structure is different among complex I and complex II, which are formed by immersing nylon-6 sample in the iodine solution of different concentration (0.5 and 3 M, respectively). The similar structure model was proposed also for nylon-66. The thus-constructed crystal structure models reproduced the observed X-ray diffraction patterns quite well. By a comparison of the X-ray diffraction data observed for the doubly oriented samples, the geometrical relation was revealed between the pristine nylon crystal and the nylon−iodine complexes.

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Section: Resultsmentioning

confidence: 99%

Crystal Structures of Nylon–Iodine Complexes

Tashiro,

Gakhutishvili,

Takahama

2024

Macromolecules

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“…The crystal unit cell is the smallest structural element that possesses physical properties, including thermal, optical, electrical, and mechanical properties. Structure analysis of polymer crystals is most often performed using uniaxial-oriented fiber diffraction. − Since the 1950s, with the development of new polyesters, the crystal structures of these polymers have been revealed. − Most of their unit cells belong to orthorhombic, e.g., poly(lactic acid) (PLA), poly(ε-caprolactone) (PCL), poly(glycolic acid) (PGA) α form, , poly(3-hydroxybutyrate) (PHB), and poly(3-hydroxyvalerate) (PHV), or monoclinic cells, such as poly(butylene succinate) (PBS) and poly(butylene adipate) (PBA) . Incorporating an aromatic ring in the backbone usually reduces the symmetry to triclinic, such as in poly(ethylene terephthalate) (PET), PBT, and poly(butylene-2,6-naphthalate) (PBN) …”

Section: Introductionmentioning

confidence: 99%

Crystal Structure and Polymorphism of Poly(butylene-trans-1,4-cyclohexane dicarboxylate)

Hu,

Ma,

Zhou

et al. 2024

Macromolecules

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The crystal structure analysis of a cycloaliphatic polyester, poly(butylene-trans-1,4-cyclohexane dicarboxylate) (PBCE), is performed by X-ray fiber diffraction. Depending on the cooling condition, two crystal forms are identified (α and β). The α form is obtained by slow cooling from the melt, while the β form is generated during fast cooling. The α form has a triclinic unit cell with a P1̅ space group, with parameters of a = 5.46 Å, b = 6.89 Å, c = 13.51 Å, α = 138.37°, β = 109.42°, and γ = 63.30°. One PBCE chain is located in the unit cell with the chair conformation aliphatic rings and all-trans-conformation methylene segmental parts. The structural transition and polymorphic transition during the heating and stretching process of PBCE are investigated by in-situ X-ray scattering. During heating, both the α and β forms show significant lattice distortion and eventually transform directly into the isotropic melt state. The volumetric thermal expansion coefficient of the PBCE α form was twice that of its unsaturated analogue, poly(butylene terephthalate). On the other hand, the irreversible β−α transition occurs during stretching, indicating that the β form is a metastable phase.

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“…Recently, Guillory et al synthesized and polymerized ( R )- and ( S )-3-( tert -butyl-dimethylsiloxy)cyclopentene, followed by hydrogenation and deprotection, to give regioregular, isotactic EVOH with hydroxyl groups located every five carbons along the backbone (60 mol % ethylene content); however, the barrier properties of these materials were not examined. Further work was recently reported by Tashiro et al on the detailed analysis of the crystal structure of this polymer. In this work, we investigate the barrier properties of a regioregular, isotactic EVOH polymer with 75 mol % ethylene to compare the barrier performance with atactic and regiorandom derivatives with the hypothesis that even higher degrees of order in the polymeric backbone will lead to enhanced intermolecular interactions, higher levels of crystallinity, higher glass-transition temperatures, and even higher water and oxygen barrier properties in a single material.…”

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“…This shows that structural regularity and melt-processing together can furnish a monomaterial with competitive oxygen permeability but greatly improved water permeability, eliminating difficulties in recycling multilayer barrier packaging. In the future, more work could be done to investigate the crystal structure of the ROMP-derived polymers from drawn fibers to determine the nature of P O2 differences from intermolecular hydrogen-bonding, similar to that of Tashiro et al 23 …”

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Regio- and Stereoregular EVOH Copolymers from ROMP as Designer Barrier Materials

Dingwell,

Hillmyer

2024

ACS Polym. Au

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This work aimed to decrease the water permeability (P H2O ) while simultaneously maintaining low oxygen permeability (P O2 ) in ethylene vinyl alcohol (EVOH)-based copolymers by introducing high levels of backbone regioregularity and stereoregularity. Both regioregular atactic and isotactic EVOH samples with 75 mol % ethylene were prepared by a ring-opening metathesis polymerization (ROMP)-hydrogenation-deprotection approach and then compared to commercial EVOH(44) (containing 44 mol % ethylene) as a low P O2 standard with poor water barrier characteristics (i.e., high P H2O ). The high levels of regioregularity and stereoregularity in these copolymers increased the melting temperature (T m ), degree of crystallinity (χ c ), and glass-transition temperature (T g ) compared to less regular structures. EVOH(44) demonstrated the highest T m but lower χ c and T g values as compared to that of the isotactic polymer. Wide-angle X-ray scattering showed that semicrystalline EVOH(44) exhibited a monoclinic structure characteristic of commercial materials, while ROMPderived polymers displayed an intermediate structure between monoclinic and orthorhombic. Tensile testing showed that isotacticity resulted in brittle mechanical behavior, while the atactic and commercial EVOH(44) samples had higher tensile toughness values. Although EVOH(44) had the lowest P O2 of the samples explored, the atactic and tough ROMP-derived polymer approached this value of P O2 while having a P H2O over 3 times lower than that of commercial EVOH(44).

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Crystal Structures of Isotactic and Atactic Poly(1-pentamethylene alcohol)

Cited by 3 publications

References 31 publications

Crystal Structures of Nylon–Iodine Complexes

Crystal Structures of Nylon–Iodine Complexes

Crystal Structure and Polymorphism of Poly(butylene-trans-1,4-cyclohexane dicarboxylate)

Regio- and Stereoregular EVOH Copolymers from ROMP as Designer Barrier Materials

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