Dynamic Behavior of Poly(2-vinylpyridine) in Solution Studied by 13C Nuclear Magnetic Relaxation

Abstract

The dynamics of poly(2-vinylpyridine) in chloroform solution has been examined by 13C spin-lattice relaxation time and NOE measurements as a function of temperature. The experiments were performed at 50.3 and 100.6 MHz. The backbone carbon relaxation data have been analyzed in terms of six motional models. Among these models, the models which consider conformational transitions and bond librations for the backbone were found to be more successful. Pyridyl ring motion has been modeled as a restricted rotation with the rotational amplitude varying with temperature. The activation energy parameters obtained from the relaxation data of the pyridyl ring carbon have been compared with the energy barrier for ring rotation estimated from conformational energy calculations using the AMI semiempirical quantum chemical method. The results of the conformational energy calculations support the description of pyridyl ring motion as a restricted rotation.

13C NMR Relaxation of iso-Poly(2-vinylpyridinium chloride) in Aqueous Solution. Effects of Electrostatic Interactions on Local Chain Dynamics

“…Finally, we will briefly discuss the effect of tacticities on the local chain dynamics. Comparing our fitting parameters with those of Ravindranathan et al, 12 we found the significant difference in the libration angles: our data are 24.0° and 27.0° for methine and methylene carbons, respectively, while their data are 21.3° and 25. 7o.…”

“…studied the local chain dynamics of ata-P2VP in chloroform, 12 and reported that all the experimental data of main chain carbons are in good agreement with the Dejean-Laupretre-Monnerie (DLM) model, 13 which was modified from the Hall---· · · ----------t To whom correspondence should be addressed.…”

“…+ sin 4 y(l-cos 21X)]J(Tt, w)} (12) where y is the angle between the internuclear vector and the axis of rotation and IX is the angular amplitude of oscillation. Here, we assumed that the temperature dependence of the amplitude of oscillation is given by IX= CT 1 1 2 , which was employed for the phenyl ring motions by Gronski et a/.…”

Carbon-13 Relaxation Study of Chain Segmental Motion and Side-Chain Internal Rotations of Poly(isobutyl methacrylate) in Solution

“…Models which describe backbone motion in terms of conformational transitions occurring in short segments of a polymer chain have been found to be successful in reproducing the experimental T 1 versus temperature curve on the lower correlation time side of the T 1 minimum. However, recent studies have shown that a more rigorous test for the validity of a model is its ability to reproduce the experimentally observed T 1 minimum. − ,− Models which include librations of the backbone C−H vectors, in addition to conformational transitions, have been found to be superior in this regard.…”

“…The dynamical processes which occur in polymer chains are mainly the rearrangement processes which occur in short segments of the backbone and side-chain motions. There are several models which describe backbone motion in terms of the conformational transitions, and these have been reviewed extensively. − However, recent studies have shown that more localized motions, namely librations of the C−H vectors of the backbone should also be considered in addition to the conformational transitions, in order to understand the differences in the dynamics of the C−H vectors at different sites of the backbone. − Several models have been proposed to describe internal motions in the side chains. For alkyl side chains, the models consider multiple internal rotations, involving the dihedral angles along the chain.…”