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Complexes of starch polysaccharides and poly(ethylene co‐acrylic acid): Structure and stability in solution
Author(s) -
Shogren R. L.,
Greene R. V.,
Wu Y. V.
Publication year - 1991
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1991.070420625
Subject(s) - amylose , amylopectin , starch , chemistry , aqueous solution , acrylic acid , polymer chemistry , solvent , polysaccharide , urea , organic chemistry , copolymer , polymer
Chiroptical methods have been used to study the conformation and interactions of amylose and amylopectin with poly(ethylene co ‐acrylic acid) (EAA) in aqueous solution. These studies, along with X‐ray diffraction and solid‐state NMR data, show that amylose and EAA, as well as amylopectin and EAA, form helical V ‐type inclusion complexes when mixed in aqueous suspension. This structure apparently accounts for the partial compatibility observed in films containing starch and EAA. About 2/3 by weight of EAA does not interact with amylose and probably represents the ethylene‐rich central core of the EAA micelle. EAA/amylose complexes in 10 m M NaOH were stable to temperatures > 90°C, whereas EAA/amylopectin complexes in the same solvent were largely disrupted at this temperature. Urea, at a concentration of 8 M , further destabilized both EAA/amylopectin and EAA/amylose complexes. Solutions with an alkaline pH (> 9.5) dispersed EAA optimally and allowed maximum complexing with amylose. At pH values > 13, the EAA/amylose complexes were weaker, most likely due to electrostatic repulsion between ionized hydroxyl groups of amylose and carboxyl groups of EAA.