Excluded-Volume Effect on Dipole Moments of Polymer Chains
1971; Springer Nature; Volume: 2; Issue: 3 Linguagem: Inglês
10.1295/polymj.2.416
ISSN1349-0540
AutoresKazuo Nagai, Toshihide Ishikawa,
Tópico(s)Surfactants and Colloidal Systems
ResumoThe excluded-volume effect on dipole moments of linear polymer chains is investigated by the perturbation method. Fixman’s formulation is followed here except for molecular models. In place of the multi-Gaussian-subchain model a more realistic model is adopted. The expansion factor αu for the dipole moment is found, up to the term in z3, to be αu2=1+(C1z+C2z2+C3z3+···)(‹r·u›02/‹r2›0‹u2›0) where r and u are the end-to-end and dipole-moment vectors, αu2=‹u2›/‹u2›0, the averages without and with the subscript 0 refer to those in the presence and in the absence of the excluded volume, and C’s and z are the familiar quantities in the similar expression for the end-to-end distance, αr2=1+C1z+C2z2+C3z3+···. This result strongly suggests αu2−1=(‹r·u›02/‹r2›0‹u2›0)(ατ2−1) An expression for ‹r·u›0 is given on the basis of the rotational-isomeric-state approximation for skeletal-bond rotations. From a structural symmetry consideration it is concluded that ‹r·u›0=0 and hence the excluded volume has no effect on dipole moments for polymers with no distinguishable direction along chain contours.
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