M. Dosiere, STRUCTURE AND CRYSTALLIZATION OF MOLECULAR-COMPLEXES BETWEEN POLY(ETHYLENE OXIDE) AND HYDROXYBENZENES, Journal of macromolecular science. Physics, B35(3-4), 1996, pp. 303-328
The phase diagrams of the binary systems poly(ethylene oxide) (PEO)-re
sorcinol and poly(ethylene oxide)-p-nitrophenol show the presence of m
olecular complexes with well-defined stoichiometries. The crystal stru
cture of these two molecular complexes has been determined from wide-a
ngle x-ray diffraction patterns of stretched films and spherulites. Th
e morphology of the two complexes crystallized from the melt is invest
igated by differential scanning calorimetry and small-angle x-ray scat
tering. The crystallization of the PEO-resorcinol complex from the mel
t gives integral-folded crystals with either extended chains (EC) or n
-folded chains (n-FC). As observed for PEO oligomers, the fraction of
EC crystals of the PEO-resorcinol complex increases with the crystalli
zation temperature to give finally only EC crystals but in a larger ra
nge of crystallization temperatures than for pure PEG. On the other ha
nd, the PEO-p-nitrophenol complex crystallizes over all the studied cr
ystallization range as stable nonintegral-folded (NIF) crystals. Two p
roposals related to the crystal structure of these complexes and their
mode of growth are invoked to explain these two greatly different mor
phologies at the lamellar level.