A Spectroscopic Analysis of the Structure of a Hexafluoroisobutylene-Vinylidene Fluoride Copolymer

Hsu, Shaw Ling; Sibilia, J. P.; O'Brien, Kennedy P.; Snyder, Robert

doi:10.1021/ma60065a028

Cited by 10 publications

(3 citation statements)

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“…As a consequence of molecular interactions arising from chemical or physical effects (hydrogen bonding or dipole association), shifts in the absorption peak are observed. In the polymer field, vibrational spectroscopy has been widely conducted to analyze the chain configuration, , chain conformation, − and crystallization kinetics. , For example, complex formation between the nitrile group of NBR and metal cations has been reported. − In addition to the peak at 2240 cm –1 , corresponding to the symmetric stretching vibration mode of the nitrile group of NBR, a new shoulder appeared at 2270 cm –1 and became stronger with increasing amounts of Li after the addition of Li salts. For rubber, the flexibility of the main chain is also important, as described above.…”

Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Relationship between the Relative Dielectric Constant and the Monomer Sequence of Acrylonitrile in Rubber

et al. 2020

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Acrylonitrile-butadiene rubbers (NBRs) have a lower glass transition temperature (T g) and a higher dielectric constant than other rubbers. To understand how a low T g and a high dielectric constant are compatible, we focused on the acrylonitrile (AN) monomer sequence in rubber and synthesized random and alternating copolymers to evaluate the effect of the sequence. The AN monomer sequence dependence of the relative dielectric constant was investigated by the C–N stretching vibration of the nitrile group through Fourier transform infrared spectroscopy and internal rotation potential energy measurements around the C–C bond within the nitrile group based on dimer model calculations. The alternating copolymers, including NBR, showed a higher dielectric constant than random copolymers. The alternating copolymer shifted from ∼2243 cm–1 for polyAN to ∼2236 cm–1 for NBRs, while the random copolymer only shifted to ∼2239 cm–1. The peak of the C–N stretching vibration was correlated with the AN sequence. The sequence dependence of the shift can be explained by the C–N bond length calculation. The internal rotation potential energy between gauche and trans of the NBR model was the lowest, indicating that the NBR main chain is flexible and that AN in the main chain rotates easily. Therefore, NBR has a high dielectric constant and a low T g because of the presence of an alternating sequence and the flexibility of the NBR main chain.

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Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Relationship between the Relative Dielectric Constant and the Monomer Sequence of Acrylonitrile in Rubber

et al. 2020

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“…1 However, HFIB is readily copolymerized with vinylidene fluoride (VDF). 2 Infrared, 3 dielectric relaxation, 4 and X-ray diffraction 5 studies of the copolymer, HFIB-co-VDF, have been reported, indicating the crystalline (T m ¼ 327 C) and alternating structure of the copolymer. Pochan et al applied the standard distribution of the melting point (T m ) and the glass transition temperature (T g ): T g ¼ 0.66 T m , 4,6 and the T g of HFIB-co-VDF was estimated to be 132 C and the hypothetical HFIB homopolymer T g was postulated to be 197 C. These high T g values were accounted for the chain stiffness due to the steric hindrance and the electronic repulsion.…”

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Alternating copolymers of hexafluoroisobutylene with vinyl trifluoroacetate and vinyl pentafluorobenzoate

Mikeš

Teng

Koike

et al. 2012

J. Polym. Sci. A Polym. Chem.

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Copolymerizations of hexafluoroisobutylene (HFIB) with vinyl pentafluorobenzoate (VPFB) and vinyl trifluoroacetate (VTFA) were carried out in bulk using perfluorodibenzoyl peroxide as the radical initiator. The copolymers obtained were characterized by proton and fluorine NMR spectroscopy. The monomer reactivity ratios in the polymerization of HFIB with VPFB were r 1 (HFIB) ¼ 0, r 2 (VPFB) ¼ 0.373, and r 1 r 2 ¼ 0. The results indicated that these copolymers have alternating structures. Similarly, the copolymers of HFIB and VTFA also showed alternating structures. The films of HFIB-co-VPFB were prepared by casting THF solution of polymers. Films obtained were flexi-ble and transparent. The refractive indices of copolymers were 1.4549, 1.4490, and 1.4438 at 532, 633, and 839 nm, respectively. The average T g s of HFIB-co-VTFA and HFIB-co-VPFB were 52 and 71 C, respectively. From these results, the T g of the hypothetical HFIB homopolymer is postulated to be in between 70 and 90 C, which may be useful in the assessment of T g s of HFIB copolymers with other vinyl monomers. V C 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 50: 4717-4720, 2012

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Vibrational Spectroscopy

Hsu¹

2002

Encyclopedia of Polymer Science and Technology

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This article presents various applications of vibrational spectroscopy for analysis of polymer structure. The relative merits of vibrational spectroscopy versus other techniques for characterization of polymer structure are discussed. Special emphasis is given to analysis of chain configuration, conformation, interchain interactions, crystallization behavior, and crystalline region size. Experimental data combined with data provided by normal coordinate analysis were utilized in analysis of spectroscopic features associated with disordered chains. Specialized topics such as amount of free volume, phase transformation, microspectroscopy, segmental orientation, and surface analysis are presented. Analysis of structural dynamics using double modulation spectroscopy and time resolved spectroscopy is also addressed.

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A Spectroscopic Analysis of the Structure of a Hexafluoroisobutylene-Vinylidene Fluoride Copolymer

Cited by 10 publications

References 7 publications

Relationship between the Relative Dielectric Constant and the Monomer Sequence of Acrylonitrile in Rubber

Relationship between the Relative Dielectric Constant and the Monomer Sequence of Acrylonitrile in Rubber

Alternating copolymers of hexafluoroisobutylene with vinyl trifluoroacetate and vinyl pentafluorobenzoate

Vibrational Spectroscopy

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