Theory of Relaxation Phenomena in Polymers. I. Rotational Motion of Side Elements around the Backbone

Work, R. N.; Fujita, Shigeji

doi:10.1063/1.1727400

Cited by 24 publications

(4 citation statements)

References 17 publications

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“…Van Beek and Hermans 20 and also Tanabe and Okano, 21 who treated the problem by the spring-bead model, showed that a frequency of maximum loss which does not depend on the degree of polymerization can be obtained, but the shape of the absorption curve derived was Debye-type. Work and Fujita 22 introduced a correlation length between dipolar reorientations, and derived a nonsymmetrical absorption curve. The theoretical curve, however, was very different from that of our observation.…”

Section: Discussionmentioning

confidence: 99%

Dielectric Behaviour of Some Vinyl-Type Polymers in Dilute Solution

Mashimo

Chiba

1973

Polym J

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Dielectric loss measurements using frequencies from 1 to 150 MHz were carried out on four vinyl-type polymers in dilute solutions (PVC, PpCS, PpBS, and PV Ac in toluene, dioxane, and carbon tetrachloride) at temperatures from -23° to 60°C. The shape of the absorption curve is always asymmetric, irrespective of the kind of polymer, molecular weight of the polymer, solvent, and temperature. The relaxation time has no molecular-weight dependence. It does, however, depend on the solvent, and is approximately proportional to the solvent viscosity. The activation energy, ilHA is 3.2-5.9 kcal/mo! for each solution, and depends on that of the solvent viscosity, ,dH~, in the manner described by ilHA=ilH~+C, where C is a constant. C is proposed to represent the potential energy for the conformational change. It is also proposed that two relaxation mechanisms, a diffusion-controlled mechanism for segmental rotation and a site model, should be taken into consideration simultaneously in order to interpret the dielectric behaviour. KEY WORDS

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Section: Discussionmentioning

confidence: 99%

Dielectric Behaviour of Some Vinyl-Type Polymers in Dilute Solution

Mashimo

Chiba

1973

Polym J

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“…The theory considered an extension of Glauber’s model for the time-dependent statistics of the Ising chain . The model employs an infinitely long array of equally spaced, rigid, permanent electric dipoles oriented at right angles to a linear axis and with rotational freedom (e.g., rotamers). , The theory further explored the effects of chain curvature and of a finite chain length. Following Glauber, interactions within the chain were included by means of a time-dependent angular correlation function.…”

Section: Resultsmentioning

confidence: 99%

Dipolar Relaxation in Functionalized Poly-p-phenylenes Bearing Ultrastrong Dipoles Perpendicular to the Backbone

et al. 2018

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Local polymer dynamics are studied in polymers bearing dipoles rigidly attached to the backbone. The compounds are based on cyano-substituted dihydrobenzimidazoles bearing ultrastrong dipole moments (∼12 D per repeat unit) incorporated in a poly-p-phenylene backbone, giving rise to polymers with rigid dipoles perpendicular to the chain. They belong to type B polymers according to the Stockmayer classification. They are ideal model systems for studying rotational isomers in the gas phase and the self-assembly and local dynamics in the solid state. Gas phase calculations (DFT) provided the dipole moments, the energetic barriers, and the backbone conformation as a function of the dipole strength and dipole separation. Calculated dipole moments show an odd–even effect as a function of dipole separation. Specific rotational isomers that maximize the dipole moment are obtained. In the solid state, dielectric spectroscopy and site-specific NMR techniques revealed that packing through intermolecular forces such as van der Waals, π–π, and dipole–dipole interactions dictates the dynamics. Dielectric spectroscopy further identified two modes, both with Arrhenius temperature dependence and activation energies of 20–23 kcal/mol. Combined results attribute the faster process to a libration motion of the highly polar group reorienting only the nonplanar five-membered ring and the slower process to larger amplitude and/or correlated motions of the polar groups. These dynamic results are in agreement with structural investigations (X-ray diffraction) demonstrating that type B polymers in the bulk have rigid backbones.

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“…The model Hamiltonian may also be used in other contexts, for instance to obtain some information on the dielectric loss of polymers containing a group with a strong dipole moment (Work and Fujita 1966). Also, if the force constants joining the molecular impurity to atoms in the other two directions of space are small compared to the ones considered in the model, chain plus molecule may be seen as a longitudinal defect (Agrawal 1971).…”

Section: Introductionmentioning

confidence: 99%

IR absorption spectrum of molecules trapped in matrices. I. The libron-phonon coupling in 1D

Blaisten‐Barojas¹,

Allavena²

1976

J. Phys. C: Solid State Phys.

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Theoretical expressions are obtained for the infrared absorption coefficient of a one-dimensional monatomic lattice containing one diatomic dubstitutional impurity. The diatomic molecule interacts with the environment introducing high rotational barriers that reduce the molecular rotation to a libration coupled to the host-lattice vibrations (libronphonon coupling). This is equivalent to the explicit consideration of static and dynamic interactions on the lineshape function. It is found that the absorption coefficient contains three main components associated with the pure vibration and libration spectra and with the combination spectrum of libration-vibration. These expressions are worked out in the harmonic and anharmonic approximation of the system Hamiltonian. Broadening of the absorption lines is obtained when the libration frequency falls inside the phonon band. The anharmonicities in the dynamical interaction (only third-order terms have been kept) give rise to an important temperature dependence of the shift and width of lines. Numerical results of the absorption coefficient of CO trapped in linear chains of Ne, Ar, Kr and Xe interacting via molecular-pair potentials are discussed. The near-infrared spectrum is qualitatively in agreement with the measured vibrational frequencies.

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Theory of Relaxation Phenomena in Polymers. I. Rotational Motion of Side Elements around the Backbone

Cited by 24 publications

References 17 publications

Dielectric Behaviour of Some Vinyl-Type Polymers in Dilute Solution

Dielectric Behaviour of Some Vinyl-Type Polymers in Dilute Solution

Dipolar Relaxation in Functionalized Poly-p-phenylenes Bearing Ultrastrong Dipoles Perpendicular to the Backbone

IR absorption spectrum of molecules trapped in matrices. I. The libron-phonon coupling in 1D

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