LOCAL DYNAMICS OF POLYMER-CHAIN IN AN EXTERNAL DIPOLE FIELD

An analytical theory is developed that describes local relaxation properties of a freely jointed chain composed of rigid units and oriented by a dipole field. The theory takes into account the bond reactions. The conformation properties and local mobilities of such system were modeled by the method of brownian dynamics. The chain segments are oriented along the field. The order parameter of the segments and the degree of chain deformation increase with the field amplitude. The rotational mobility of the chain segments was studied. In contrast to the dynamic properties of a chain exposed to a strong field of the quadrupole symmetry, both longitudinal and transverse (with respect to the dipole field direction) rotational relaxation times of the chain segments decrease with increasing degree of deformation. The spectrum of relaxation times of the normal modes of the chain splits into two branches, corresponding to the longitudinal and transverse motions relative to the direction of the external field. The two branches are characterized by different dependences of the relaxation times of various scales on the degree of chain deformation. An analytical theory is presented that satisfactorily describes the dependence of the relaxation time on the dipole field strength obtained in a numerical experiment.