<sup>1</sup>H NMR studies of molecular relaxations of poly‐1‐butene

Maring, Daniel; Meurer, B.; Weill, G.

doi:10.1002/polb.1995.090330809

Cited by 26 publications

(38 citation statements)

References 52 publications

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“…This is supported by the previous investigation. 19 The 13 C line-width data, thus, indicate that the spin diffusion between the forms I′ and III phases leads to the similar 1 H T 1F values. Namely, form I′ does not form domains, the size of which is larger than ca.…”

Section: Resultsmentioning

confidence: 83%

Chain Dynamics, Conformations, and Phase Transformations for Form III Polymorph of Isotactic Poly(1-butene) Investigated by High-Resolution Solid-State¹³C NMR Spectroscopy and Molecular Mechanics Calculations

et al. 2002

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High-resolution solid-state 13 C NMR spectroscopy and MM3 molecular mechanics calculations have been applied to investigate side-chain conformations, side-and main-chain dynamics, and phase transformations of the form III polymorph of isotactic-poly(1-butene) (i-PB). MM3 calculations indicate that the t-g′ side-chain conformation is much more stable than the g′-g and g-t side-chain conformations in the crystal lattices of form III. The 13 C cross-polarization magic-angle spinning (CPMAS) NMR spectrum at 199 K shows that the methyl group in the side chain adopts only the t-g′ conformation. Upfield shift for the 13 C methyl signal above 338 K indicates dynamic disorder in the side-chain conformations. The 13 C two-dimensional exchange NMR reveals that the polymer chains in form III consist of two components. The 74% polymer chains execute the 90°helical jump motion with an activation energy of 79.3 ( 5.6 kJ/mol, while the residual chains are immobile. It is found that the 90°helical jump motion begins to occur at the temperature very close to the glass-transition temperature (Tg). Upfield shifts for the 13 C main-chain signals at 338 K indicate the motional mode change from the 90°helical jump motion to "more or less" rotational or jump motion with different angle displacements. Above 338 K, two phase transformations from form III to forms II and I′ are confirmed in the 13 C CPMAS spectra. The 1 H spinlattice relaxation times in the rotating frame show that the transformation from form III to form I′ proceeds within the form III phase via the crystal-to-crystal process, whereas the line-shape analyses of the 13 C direct-polarization magic-angle spinning (DPMAS) NMR spectra indicate that the transformation from form III to form II proceeds via the quasi-melting/recrystallization process. The frozen chain conformations in the amorphous phase below Tg are also investigated on the basis of the 13 C chemical shifts. It is suggested that most of the main chains adopt the helical (tg′)n conformation, and the residual part adopts the (tt) conformation.

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Section: Resultsmentioning

confidence: 83%

Chain Dynamics, Conformations, and Phase Transformations for Form III Polymorph of Isotactic Poly(1-butene) Investigated by High-Resolution Solid-State¹³C NMR Spectroscopy and Molecular Mechanics Calculations

et al. 2002

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“…We obtain σ = 1.34 × 10 −2 J m −2 , 1.43 × 10 −2 J m −2 , 1.45 × 10 −2 J m −2 , and 1.46 × 10 −2 J m −2 for n = 1, 3, 6, and 18, respectively. The trigonal phase has tight 3/1 helical chains and the conformation is ordered and very rigid,35, 36 as will be discussed later. The interhelix crystallographic interaction is hence considered to be stronger, and this naturally leads to the assumption that the growth unit will be constituted from 1 or more turns of a helix; n is equal to or larger than 3, and σ is considered to take a value between 1.43 × 10 −2 and 1.46 × 10 −2 J m −2 .…”

Section: Discussionmentioning

confidence: 98%

Isotactic poly(butene‐1) trigonal crystal growth in the melt

Yamashita

Hoshino

Kato

2007

J Polym Sci B Polym Phys

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Crystal growth of the trigonal form of isotactic poly(butene‐1) (it‐PB1) was successfully observed in the melt at atmospheric pressure. The growth rate of trigonal crystals was obtained by in situ optical microscopy. It is one hundredth that of it‐PB1 tetragonal crystals. The growth rate of trigonal crystals, as well as that of tetragonal crystals, shows supercooling dependence derived from the nucleation theory. The value of the kinetic constant K of trigonal crystals is about 3.3 times larger than that of tetragonal crystals. The value of the pre‐exponential factor G0 of trigonal crystals was found to be 41 times as large as that of tetragonal crystals. The difference between these K values can be attributed to the conformational entropy of the ethyl side groups in a nucleating stem. The discrepancy found in the values of G0 could be explained by introducing pinning and nucleation barriers, which originate from the crystal thickness δlc, which does not depend on the crystallization temperature. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 684–697, 2007

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“…20 There are several solid-state NMR works on iPB1. [21][22][23][24][25][26][27] Maring et al 22 using 1 H second moments, detected reduced mobility of iPB following solid-solid transitions. Beckham et al 24 detected overall segmental motions in form II above T g ¼À23 1C.…”

Section: Introductionmentioning

confidence: 99%

Critical roles of molecular dynamics in the superior mechanical properties of isotactic-poly(1-butene) elucidated by solid-state NMR

Miyoshi

Mamun

2011

Polym J

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Isotactic-poly(1-butene) (iPB1) shows superior mechanical properties after crystal-crystal transitions. Recently, Miyoshi et al. found that crystalline stems in metastable tetragonal crystal perform uniaxial rotational diffusions accompanying side-chain conformational transitions in the fast motional limit (correlation time, /s c S o10 À7 s; Macromolecules 2010, 43, 3986-3989.). In this study, molecular dynamics in stable trigonal crystal is investigated by solid-state nuclear magnetic resonance, which indicates that crystalline stems and side-chain conformations are completely fixed up to melting points (/s c S 410 s). In addition, lamellar thickness, /lS of iPB1 and a low isotacticity iPB1 (low_iPB1) with /mmmmS¼78%, respectively, were investigated by small-angle X-ray scattering. The low_iPB1 sample shows very week supercooling dependence of /lS (B5 nm), whereas iPB1 shows strong supercooling dependence of /lS (10-28 nm). On the basis of molecular dynamics and /lS results, molecular dynamics effects on structures and unique mechanical property of iPB1 are discussed.

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¹H NMR studies of molecular relaxations of poly‐1‐butene

Cited by 26 publications

References 52 publications

Chain Dynamics, Conformations, and Phase Transformations for Form III Polymorph of Isotactic Poly(1-butene) Investigated by High-Resolution Solid-State¹³C NMR Spectroscopy and Molecular Mechanics Calculations

Chain Dynamics, Conformations, and Phase Transformations for Form III Polymorph of Isotactic Poly(1-butene) Investigated by High-Resolution Solid-State¹³C NMR Spectroscopy and Molecular Mechanics Calculations

Isotactic poly(butene‐1) trigonal crystal growth in the melt

Critical roles of molecular dynamics in the superior mechanical properties of isotactic-poly(1-butene) elucidated by solid-state NMR

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1H NMR studies of molecular relaxations of poly‐1‐butene

Cited by 26 publications

References 52 publications

Chain Dynamics, Conformations, and Phase Transformations for Form III Polymorph of Isotactic Poly(1-butene) Investigated by High-Resolution Solid-State13C NMR Spectroscopy and Molecular Mechanics Calculations

Chain Dynamics, Conformations, and Phase Transformations for Form III Polymorph of Isotactic Poly(1-butene) Investigated by High-Resolution Solid-State13C NMR Spectroscopy and Molecular Mechanics Calculations

Isotactic poly(butene‐1) trigonal crystal growth in the melt

Critical roles of molecular dynamics in the superior mechanical properties of isotactic-poly(1-butene) elucidated by solid-state NMR

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¹H NMR studies of molecular relaxations of poly‐1‐butene

Chain Dynamics, Conformations, and Phase Transformations for Form III Polymorph of Isotactic Poly(1-butene) Investigated by High-Resolution Solid-State¹³C NMR Spectroscopy and Molecular Mechanics Calculations

Chain Dynamics, Conformations, and Phase Transformations for Form III Polymorph of Isotactic Poly(1-butene) Investigated by High-Resolution Solid-State¹³C NMR Spectroscopy and Molecular Mechanics Calculations