Global phase diagrams for polymer-solvent mixtures within the modified Tompa model

We construct the global phase diagrams (GPDs) for polymer-solvent mixtures utilizing the modified Tompa model. We obtained the Griffiths shield regions (GSRs), the zones that coupling constants are almost equal, are obtained on the GPDs. We examine and discuss the influences of various segment sizes of polymer molecules on the GPDs and the GSRs. We observe that the GPDs are symmetrical around zeta = 0 for the equal-size segments of polymer molecules and the break down in the symmetric features of the GPDs rises as differences of segments of polymer molecules rise. Moreover, the types IV*, VI and VII phase behaviors are seen for differences of segments of polymer molecules in addition to the types I, I-A, II, II-A, III, III-HA, IV, V and V-A according to the van Konynenburg and Scott phase behavior classification. It is also observed that differences in the polymer molecules segments effect on the sizes of the phase type domains and the types of phase behaviors. (C) 2021 Published by Elsevier B.V