Authors

Citation

Vp. Privalko et al., STRUCTURE-DEPENDENT MAGNETIC-SUSCEPTIBILITY OF SHARP POLY(ETHYLENE OXIDE) FRACTIONS, Journal of macromolecular science. Physics, B37(6), 1998, pp. 765-771

Citations number

24

Language

INGLESE

art.tipo

Article

Categorie Soggetti

Polymer Sciences

Journal title

ISSN journal

0022-2348

Volume

B37

Issue

6

Year of publication

1998

Pages

765 - 771

Database

ISI

SICI code

0022-2348(1998)B37:6<765:SMOSPO>2.0.ZU;2-I

Abstract

Nine sharp fractions of poly(ethylene oxide) (PEO) glycol with number-
average molar masses [M-n] in the range from 0.6 x 10(3) to 20 x 10(3)
(PEO-0.6 to PEO-20) were characterized by magnetic susceptibility chi
measured in the temperature interval 293 K to 378 K. In contrast to t
he liquidlike PEG-0.6 with temperature-invariant chi, the values of ch
i for each of the remaining solid samples, after the initial increase,
exhibited two plateaus separated by a relatively narrow temperature i
nterval of their second increase. The jumps of chi at lower and higher
temperatures were attributed to a solid-state transition of-unspecifi
c nature and to the melting of the crystal fraction, respectively. The
temperature-invariant values of chi(n) in the melt state above T-m pa
ss through a minimum for the sample PEG-2.0 and then increase again wi
th [M-n] to a limiting value chi(infinity) = -0.622 x 10(-6). It is co
ncluded that a considerable contribution of the molar-mass-dependent '
'paramagnetism'' chi(p) = chi - chi(d) (where chi(d) is the diamagneti
c contribution estimated by Kirkwood's equation) to the total magnetic
susceptibility of PEO fractions reflects distortions of the spherical
symmetry of the electron shells around chain atoms resulting from the
discontinuous change of both inter- and intrachain interactions as th
e [M-n] increases through and above the critical crossover molar mass
[M-cr] = 2 x 10(3).