Folding of Polymer Chains in the Early Stage of Crystallization

Yuan, Shichen; Li, Zhen; Hong, You‐lee; Ke, Yutian; Kang, Jia; Kamimura, Akihiro; Otsubo, Akihiro; Miyoshi, Toshikazu

doi:10.1021/acsmacrolett.5b00818

Cited by 44 publications

(59 citation statements)

References 31 publications

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“…It is worthwhile to note that recent MD simulation of coarse grained Poly(vinyl alcohol) (PVA) model predicted < n > to be ~2.4 in the melt-grown and < n > is independent of T c [73,74]. These simulation results are very consistent with recent ssNMR observations [52,53,54,55,56].…”

Section: Melt-grown Crystalssupporting

confidence: 85%

“…The simulated DQ curve based on the shortest 13 C– 13 C interstem distance of 4.0 Å and relaxation value of T 2 = 8.3 ms can reproduce the experimental data (red curves in Figure 1e,f). Similar packing analysis was conducted on i PP [53,54] and PLLA crystals [58,63]. In all systems, the internuclear distances determined by NMR are consistent with those by WAXD and electron diffraction (ED) within 5% errors.…”

Section: Packing Analysismentioning

confidence: 53%

“…[54] The mesomorphic domain includes only ~60 stems and its size is comparable to critical nuclei in the initial stage of crystallization predicted by MD simulation. [54] Figure 11A depicts the DQ buildup curve for 15% 13 C CH 3 enriched i PP mesomorphic blends with non-labeled i PP and simulated curves on the basis of isolated model, as depicted in Figure 11B, and nanoclusters (Figure 11C). The comparison indicates that the i PP chains fold 3–4 times during rapid quenching into icy water.…”

Section: Melt-grown Crystalsmentioning

confidence: 99%

“…The comparison indicates that the i PP chains fold 3–4 times during rapid quenching into icy water. [54] From the NMR observations, it is concluded that the i PP chains initiate nucleation via self-folding in the early stage of crystallization.…”

Section: Melt-grown Crystalsmentioning

confidence: 99%

“…Recently, 13 C– 13 C double quantum (DQ) NMR spectroscopy has been applied to elucidate chain trajectory and packing structures for 13 C selectively isotopic enriched isotactic -Poly(1-butene) ( i PB1), isotactic -poly(propylene) ( i PP), and poly(L-lactic acid) (PLLA) in the melt- and solution-grown crystals [52,53,54,55,56,57,58,59,60,61,62,63]. 13 C– 13 C dipolar interaction is governed by internuclear distance, spin topology, and spin number.…”

Section: Introductionmentioning

confidence: 99%

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Chain Trajectory, Chain Packing, and Molecular Dynamics of Semicrystalline Polymers as Studied by Solid-State NMR

et al. 2018

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Chain-level structure of semicrystalline polymers in melt-and solution-grown crystals has been debated over the past half century. Recently, 13 C-13 C double quantum (DQ) Nuclear Magnetic Resonance (NMR) spectroscopy has been successfully applied to investigate chain-folding (CF) structure and packing structure of 13 C enriched polymers after solution and melt crystallization. We review recent NMR studies for (i) packing structure, (ii) chain trajectory, (iii) conformation of the folded chains, (iv) nucleation mechanisms, (v) deformation mechanism, and (vi) molecular dynamics of semicrystalline polymers.

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Section: Melt-grown Crystalssupporting

confidence: 85%

Section: Packing Analysismentioning

confidence: 53%

Section: Melt-grown Crystalsmentioning

confidence: 99%

Section: Melt-grown Crystalsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Chain Trajectory, Chain Packing, and Molecular Dynamics of Semicrystalline Polymers as Studied by Solid-State NMR

et al. 2018

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Stereocontrolled Entanglement‐Directed Self‐Alignment of Poly(lactic acid) Cylindrites

Geng

Odelius

et al. 2016

Macro Chemistry & Physics

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The concept of stereocontrolled entanglements, in which the tunable H‐bonded chiral pairs serve as crosslinks to create topological constraints on the local chain dynamics, is introduced to tailor the crystalline morphology of stereocomplex poly(lactic acid). For the entanglements to be interconnected and activated, poly(d‐lactic acid) with statistical branched architecture is incorporated, enabling the construction of 3D association with linear poly(l‐lactic acid) chains. With thermodynamically graded disentanglement relaxation for the blends, the profound influence of entanglements on the crystalline morphology is revealed during isothermal crystallization. Orderly aligned cylindrites some with an exceptional length of over 500 μm, resembling the structural features of the classical shish‐kebab superstructure, are observed in the blends penetrated with dense entanglement constraints. By contrast, only dendritic spherulites are formed in the highly disentangled blends. The selectively suppressed homo‐crystallization by the entanglements offers insights into the contribution of constraints. This bottom‐up strategy opens up pathways to engender oriented crystals of long‐range order under quiescent conditions, which has potential implications for other chiral polymers.

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Estimations of the Thicknesses of Smectic Layer and Rigid Amorphous Layer in Mesomorphic Isotactic Polypropylene with Synchrotron Small‐Angle and Wide‐Angle X‐Ray Scattering

Li,

Liu,

Lin

et al. 2024

Macro Chemistry & Physics

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Despite extensive research, the stabilization mechanism of mesomorphic isotactic polypropylene (iPP) at room temperature has not been elucidated completely. To address this issue, nanoscale structural information is indispensable. In this study, mesomorphic‐α phase transition is studied with synchrotron wide‐angle diffraction and small‐angle X‐ray scattering. It is found that during phase transition, the mobile amorphous content remained unchanged, while rigid amorphous fraction (RAF) decreased constantly, accompanied by an increase in long period. Assuming that the increase in long period is induced by the extension of the rigid amorphous coil (RAC), the thickness of RAF (RRAF) is estimated, which is found to be 2.2 nm. This value is greater than the length of b axis in α crystal cell, which can be the reason that folded‐chain iPP clusters in mesomorphic iPP cannot approach closer to form α crystal at room temperature. Besides, with RRAF, the thickness of smectic layer is estimated, which is found to be 0.9 nm. At this thickness, bulk‐free energy cannot compensate for the folded‐surface free energy, which can be the other reason that mesomorphic iPP chains cannot transit into α crystal at room temperature. The information obtained in this study is favorable for understanding the stabilization mechanism of mesomorphic iPP.

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Folding of Polymer Chains in the Early Stage of Crystallization

Cited by 44 publications

References 31 publications

Chain Trajectory, Chain Packing, and Molecular Dynamics of Semicrystalline Polymers as Studied by Solid-State NMR

Chain Trajectory, Chain Packing, and Molecular Dynamics of Semicrystalline Polymers as Studied by Solid-State NMR

Stereocontrolled Entanglement‐Directed Self‐Alignment of Poly(lactic acid) Cylindrites

Estimations of the Thicknesses of Smectic Layer and Rigid Amorphous Layer in Mesomorphic Isotactic Polypropylene with Synchrotron Small‐Angle and Wide‐Angle X‐Ray Scattering

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