DOI: 10.1140/epje/e2003-00001-6
Phase behavior and structure of an ABC triblock copolymer dissolved in selective solvent
N.P. Shusharina1, P. Alexandridis1, P. Linse2, S. Balijepalli3 and H.J.M. Gruenbauer41 Department of Chemical Engineering, University at Buffalo, The State University of New York, Buffalo, NY 14260-4200, USA
2 Physical Chemistry 1, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, S-221 00 Lund, Sweden
3 New Product & Mathematical Modeling Group, Corporate R&D, The Dow Chemical Co., Midland, MI 48674, USA
4 New Business Development, Dow Benelux N.V., 4530 AA Terneuzen, The Netherlands
palexand@eng.buffalo.edu
(Received 17 April 2002 Published online: 21 January 2003)
Abstract
A mean-field lattice theory is applied to predict the
self-assembly into ordered structures of an ABC triblock copolymer in
selective solvent. More specifically, the composition-temperature
phase diagram has been constructed for the system
(C)
14(PO)
12(EO)
17/water, where C stands for
methylene, PO for propylene oxide and EO for
ethylene oxide. The model predicts thermotropic phase transitions
between the ordered hexagonal, lamellar, reverse hexagonal, and
reverse cubic phases, as well as the disordered phase. The
thermotropic behavior is a result of
the temperature dependence of water interaction with EO- and
PO-segments.
The lyotropic effect (caused by changing the solvent concentration)
on the formation of different
structures has been found weak. The structure in the
ordered phases is described by analyzing the species volume
fraction profiles and the end segment and junction distributions.
A "triple-layer" structure has been found for each of the ordered
phases, with each layer rich in C-, PO-, and EO-segments, respectively. The
blocks forming the layers are not stretched. The dependence of the
domain spacing on polymer volume fraction and temperature is also
considered.
36.20.-r - Macromolecules and polymer molecules.
64.75.+g - Solubility, segregation, and mixing; phase separation.
61.20.Gy - Theory and models of liquid structure.
07.05.Tp - Computer modeling and simulation.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2003
