Magic angle spinning carbon-13 NMR spectroscopy of three crystalline forms of isotactic poly(1-butene)

Belfiore, Laurence A.; Schilling, Frederic C.; Tonelli, Alan E.; Lovinger, Andrew J.; Bovey, F. A.

doi:10.1021/ma00142a017

Cited by 66 publications

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“…It is very well known that the form II (tetragonal) polymorph is metastable and transforms to form I (hexagonal) at atmospheric pressure and room temperature with a half-life in the range 250-1,600 min [90]. We did not observe the same stability of the initial form II crystals when low molecular weight i-PB was coalesced from its γ-CD-IC.…”

Section: Polyolefinscontrasting

confidence: 71%

Molecular Processing of Polymers with Cyclodextrins

Tonelli

2009

Advances in Polymer Science

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We summarize our recent studies employing the cyclic starch derivatives called cyclodextrins (CDs) to both nanostructure and functionalize polymers. Two important structural characteristics of CDs are taken advantage of to achieve these goals. First the ability of CDs to form noncovalent inclusion complexes (ICs) with a variety of guest molecules, including many polymers, by threading and inclusion into their relatively hydrophobic interior cavities, which are roughly cylindrical with diameters of ∼0.5 − 1.0 nm. α-, β-, and γ-CD contain six, seven, and eight α-1,4-linked glucose units, respectively. Warm water washing of polymer-CD-ICs containing polymer guests insoluble in water or treatment with amylase enzymes serves to remove the host CDs and results in the coalescence of the guest polymers into solid samples. When guest polymers are coalesced from the CD-ICs by removing their host CDs, they are observed to solidify with structures, morphologies, and even conformations that are distinct from bulk samples made from their solutions and melts. Molecularly mixed, intimate blends of two or more polymers that are normally immiscible can be obtained from their common CD-ICs, and the phase segregation of incompatible blocks can be controlled (suppressed or increased) in CD-IC coalesced block copolymers. In addition, additives may be more effectively delivered to polymers in the form of their crystalline CD-ICs or soluble CD-rotaxanes. Secondly, the many hydroxyl groups attached to the exterior rims of CDs, in addition to conferring water solubility, provide an opportunity to covalently bond them to polymers either during their syntheses or via postpolymerization reactions. Polymers containing CDs in their backbones or attached to their side chains are observed to more readily accept and retain additives, such as dyes and fragrances. Processing with CDs can serve to both nanostructure and functionalize polymers, leading to greater understanding of their behaviors and to new properties and applications.

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Section: Polyolefinscontrasting

confidence: 71%

Molecular Processing of Polymers with Cyclodextrins

Tonelli

2009

Advances in Polymer Science

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“…Thus, the crystallinity of the form III-rich sample used in this study is concluded to be 81%. Figure 4 shows the 13 C CPMAS NMR spectra for the form III-rich sample at and above 316 K. Belfiore et al 17 showed previously that the chemical shifts of the mainchain and s-methylene signals depend on the helical conformations. We can thus get information about the phase transformations from form III into forms I′ and II through the resolved 13 C signals.…”

Section: Resultsmentioning

confidence: 99%

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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“…The MAS spectrum, Fig. 11a, shows four bands, for the four carbon sites in the repeat units, with 0.7 ppm splittings for each of the two types of CH 2 groups (35,36). In spite of the relatively small number of sites, the deconvolution of the static powder spectrum in Fig.…”

Section: Super Spectra Of Aromatic and Olefinic Carbonsmentioning

confidence: 99%

A Robust Technique for Two-Dimensional Separation of Undistorted Chemical-Shift Anisotropy Powder Patterns in Magic-Angle-Spinning NMR

Schmidt‐Rohr

2002

Journal of Magnetic Resonance

199

274

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Magic angle spinning carbon-13 NMR spectroscopy of three crystalline forms of isotactic poly(1-butene)

Cited by 66 publications

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Molecular Processing of Polymers with Cyclodextrins

Molecular Processing of Polymers with Cyclodextrins

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

A Robust Technique for Two-Dimensional Separation of Undistorted Chemical-Shift Anisotropy Powder Patterns in Magic-Angle-Spinning NMR

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Magic angle spinning carbon-13 NMR spectroscopy of three crystalline forms of isotactic poly(1-butene)

Cited by 66 publications

References 0 publications

Molecular Processing of Polymers with Cyclodextrins

Molecular Processing of Polymers with Cyclodextrins

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

A Robust Technique for Two-Dimensional Separation of Undistorted Chemical-Shift Anisotropy Powder Patterns in Magic-Angle-Spinning NMR

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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