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On The Incompatibility of Dextran and Pullulan in Aqueous Solutions and Its Modeling
Author(s) -
Eckelt Anja,
Eckelt John,
Schärtl Wolfgang,
Wolf Bernhard A.
Publication year - 2012
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.201200040
Subject(s) - pullulan , miscibility , dextran , molar mass , aqueous solution , polymer , polymer chemistry , chemistry , thermodynamics , ternary operation , phase (matter) , polymer science , polysaccharide , chemical engineering , materials science , chromatography , organic chemistry , physics , computer science , engineering , programming language
Abstract Joint aqueous solutions of branched dextran and linear pullulan are investigated with respect to their phase separation. The experiments demonstrate that the polymers are – depending on the molar mass of dextran – incompatible in aqueous solutions despite their chemical similarity. This finding can be modeled on the basis of an approach accounting for chain connectivity and conformational relaxation of the components. According to these calculations, the polymers exhibit a miscibility gap in joint solutions despite the favorable interactions between them. Using information on the subsystems H 2 O/dextran and H 2 O/pullulan, the assumption of complete miscibility of the polysaccharides is required to model the observed phase separation. This analysis predicts the existence of two islands of immiscibility for the ternary system.