Phonons in 72 helical poly(4-methyl-1-pentene)

Bahuguna, G. P.; Rastogi, Shantanu; Tandon, Poonam; Gupta, V. D.

doi:10.1016/0032-3861(96)87249-1

Cited by 12 publications

(7 citation statements)

References 15 publications

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“…The mode at 1208 cm -1 is mixed wag and twist. These lie in the same range as observed in other systems such as PAIBLA [11] and P4MP1 [18].…”

Section: Other Skeletal Modessupporting

confidence: 82%

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A study of vibrational dynamics of poly (a-n-butyl-b-l-aspartate) (panbla)

Singh¹,

Kumar²,

Kumar³

et al. 2009

ChChT

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Poly(-N-butyl--L-aspartate) (PANBLA) is nylon-3 derivative in which an alcoxycarbonyl group has been stereoregularly attached to -carbon of the repeating unit. Like poly(-isobutyl--L-aspartate) (PAIBLA) exists in two helical forms, namely hexagonal form (13/4 helix) and tetragonal form (4/1 helix), were characterized by X-ray diffraction. The hexagonal form appears to be poorly crystalline and it could not be obtained well oriented. On the other hand tetragonal form turns to be highly crystalline. Both molecular mechanics calculations and the linked-atom least square (LALS) methodology using X-ray diffraction data have revealed that an antiparallel packing of 13/4 helices with a right handed (2R) scheme of hydrogen bonds is most favourable for hexagonal form of PANBLA. Regarding tetragonal form the above techniques favour a parallel arrangement of 4/1 helices according to right handed 4R model. IR dichroism studies also support the above results. Although the vibrational dynamics of both forms of PAIBLA has been studied, no such study has been performed for PANBLA. In the present communication the vibrational dynamics of PANBLA in tetragonal form (4/1 helix) has been studied through the dispersion of normal modes. The effect of side chain nature on the dynamical behaviour has also been analyzed. Apart from detailed assignments of modes, various characteristic features of dispersion curves have been explained as arising due to internal symmetry in energy momentum space. Finally, the density of states has been used to calculate heat capacity of this polymer.

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“…The mode at 1208 cm -1 is mixed wag and twist. These lie in the same range as observed in other systems such as PAIBLA [11] and P4MP1 [18].…”

Section: Other Skeletal Modessupporting

confidence: 82%

“…The asymmetric, symmetric stretch, and scissoring modes of the methylene group of backbone (C β H 2 ) are calculated at 2899, 2859, and 1426 cm -1 respectively. The above modes lie in the same range in PAIBLA [11] and poly (4-methyl, 1-pentene) {P4MP1} [18]. These modes are highly localized and nondispersive in nature.…”

Section: Other Skeletal Modesmentioning

confidence: 79%

A study of vibrational dynamics of poly (a-n-butyl-b-l-aspartate) (panbla)

Singh¹,

Kumar²,

Kumar³

et al. 2009

ChChT

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“…Being highly localized, these modes show no dispersion. CH 2 stretches are observed at 2915 and 2850 cm −1 for cis-polybutadiene (CPBD) [5] and at 2902 and 2852 cm −1 for P4MP [7]. The C=C stretch is used for identification of the conformation of dienes.…”

Section: ](20)mentioning

confidence: 97%

“…In the case of trans-polybutadiene [6] and -polypentadiene, it is observed at 1673 and 1660 cm −1 , respectively. The CH 2 scissoring vibration, calculated at 1447 cm −1 (assigned to 1450 cm −1 ), is conformation independent and appears in the same range in CPBD [5] (1450 cm −1 ), P4MP [7] (1456 cm −1 ), and polystyrene [8] (1446 cm −1 ).…”

Section: ](20)mentioning

confidence: 98%

“…cm −1 and are assigned to 1005 and 980 cm −1 , respectively. In the case of poly(4-methyl, 1-pentene) (P4MP) [7], these modes are calculated at 1007 and 986 cm −1 . The observed peaks at 897 and 863 cm −1 are assigned to calculated frequencies at 902 and 851 cm −1 , with a major contribution coming from the rocking of the side-chain methyl group (C M2 ) and C−C stretch.…”

Section: Methyl Group Modesmentioning

confidence: 99%

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Phonon Dispersion in 1,4-cis-Poly-(2-Methyl-1,3-Pentadiene)

Misra

Kapoor

Tandon

et al. 2000

Journal of Macromolecular Science, Part B

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Polymers of 2-methyl-1,3-pentadiene are capable of existing in both isotactic, as well as syndiotactic, configuration. The isotactic 1,4-cis polymer also exists in two stable forms that have different melting points. A complete study of normal modes and their dispersion was carried out using Higgs modification of Wilson's dynamical GF matrix method and the Urey Bradley force field. The force constants have been best fitted to the Fourier transform infrared (FTIR) frequencies. Characteristic features of dispersion curves, like bunching, repulsion, and exchange of character between various pairs of modes, were observed and are discussed here. In addition, the frequency distribution function derived from dispersion curves was used to calculate the heat capacity in the temperature range 50-450 K.

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