Dynamics of PVA-gel with magnetic macrojunctions

The neutron-spin-echo spectrometer SPAN CC. Pappas et al., Physica B 276-27 8 (2000) 162] has been used for the study of the dynamics of ferrogel of Po ly(vinylalcohol) with subdomain particles of magnetite (size similar to 10 nm, concentration in gel C = 4.25 wt%.) embedded in polymer matrix. By sepa ration of coherent nuclear scattering on particles from incoherent one, con tributed by network and solvent, we distinguished the dynamical behaviours of subsystems in ferrogel. The self-correlation of magnetic particle, attac hed to network, via its conformational changes obeys the law: S-p(q,t) simi lar to exp{ - q(2)a(2)[1 - cos(2 pi (t/tau)(beta))]/2} where the a similar to 1 nm is the amplitude of particle's oscillation, and the exponent beta s imilar to (1)/(2) characterises the rotational diffusion of chain units wit h relaxation time tau similar to 0.3 ns. In the surrounding solvent, half o f the molecules showed free diffusion whereas the remaining part, situated ill the neighbourhood of polymer chains, is involved in the stretched relax ation. (C) 2001 Elsevier Science B.V, All rights reserved.