Relation of self-diffusion and the topological structure of flexible polymers as studied by NMR

Influence of Three-Spin Groups on the Primary Echo in Linear Polymers with Free Ends

“…To carry out a controlled synthesis and use of linear and cross-linked polymers, data on their structure and molecular mobility are required, which are determined by various NMR methods. The pulsed NMR relaxation method is a noninvasive and informative method for studying the structure at various levels, molecular mobility, and in particular diffusion, in a condensed medium [1][2][3][4][5][6][7]. In the presence of isolated three-spin groups in the polymer, broadening of the spectra is observed under the influence of the surrounding spins and partial averaging of their dipole interaction [8,9].…”

Characterization of Structure and Self-Diffusion of Elastomers by NMR Method

“…18 is shown that in rarely-crosslinked polymers and quasi-network of entanglements the coecient of D logarithmic depends on the average length of a chain N 0 [7].…”

“…On the basis of the general theoretical approach developed earlier [3,7] the dependences of signals of diusion attenuation and coecient of self-diusion of D in crosslinked and linear El with a various M w are investigated.…”

“…16 is carried out by means of the theory [7] for crosslinked polymers with a various chains length N 0 . Correlation function of molecular motions k m (t) can be to received from FID (Eq.…”

“…According to the theory of spin echo with magnetic eld gradient, the amplitude of the i-th echo signal A id (1 ≤ i ≤ 5) is related to the mean square of the random phase change (phase shift) δ 2 φ i due to a change in the local magnetic eld on the nucleus spin as [5,7]:…”