Membranes of the polyelectrolyte complex between chitosan and pectin were prepared by precipitating the complex from a mixture of both polysaccharides It was shown that the swelling kinetics of these membranes follows a Fickean behavior The membranes were heated at 120 °C in order to convert the –NH3+-OOC- salt bonds into amide bonds The thermally treated membranes were stable in strongly acid and basic media The extent of amide bond formation was followed by FTIR spectroscopy It was found that as the reaction time increased, both the absorbance ratio A1744/A1082 and the maximum swelling of the membrane decreased The surface morphology of the membranes did not vary appreciably with the thermal treatment

Swelling behavior of chitosan/pectin polyelectrolyte complex membranes. Effect of thermal cross-linking

Crosslinked hemicellulose citrate–chitosan aerogel foams

Thermo- and pH-responsive polyelectrolyte complex membranes from chitosan-g-N-isopropylacrylamide and pectin

Phase separation has been studied in aqueous salt solutions of non-stoichiometric polyelectrolyte complexes formed by polyacrylic acid and linear polyethylenimine. Analysis of the phase diagrams for systems formed by the polycomplex, water and NaCl, as well as an analysis of the composition of the co-existing phases, gives evidence that phase separation in such systems is a consequence of a chemical reaction involving the redistribution of the macromolecular components between the different particles of the polycomplexes. The unusual behaviour of aqueous salt solutions of polyelectrolyte complexes is caused by the reversible nature of the formation and rupture of the intermacromolecular salt bonds in the particles of the polycomplex.

Features of the phase transitions in aqueous salt solutions of non-stoichiometric polyelectrolyte complexes☆

IR spectroscopy and potentiometric titration have been used to investigate the structure of crosslinked gels based on a polyelectrolyte complex of polyacrylic acid and branched polyethyleneimine. The dependence of their physical chemical properties on the ratio of the ionic and covalent bonds between the chains of the polyelectrolytes in aqueous and salt media has been studied. It is shown that by varying the nature and the ratio of the stabilizing gel-ionic, covalent and hydrogen bonds one may within wide limits change the properties of the hydrogels of the polyelectrolyte complex, their stability in different media, swelling capacity and permeability in relation to water and dissolved substances. The patterns found are in good agreement with the structure established in this work in the polyacrylic acid-polyethyleneimine complex.

Structure and properties of crosslinked hydrogels based on the polyelectrolyte complex polyacrylic acid-polyethyleneimine

IR spectroscopy was used to study the formation of intermacromolecular amide bonds in a polyelectrolyte salt complex of polyacrylic acid and linear polyethylene imine on heating in dilute solution. It was shown that in contrast with low molecular weight systems, the reaction of intermacromolecular condensation in dilute aqueous solutions takes place to high degrees of transformation to form water-soluble products.

Intermacromolecular amidization in dilute aqueous solution of a polyelectrolyte complex of polyacrylic acid and linear polyethylene imine

Light scatter and sedimentation have been used to make a comparative study of the structure and properties of the polyelectrolyte complex (PEC) of polyacrylic acid and linear polyethyleneimine and the products of its chemical conversions in which some of the intermacromolecular salt bonds are replaced by amide bonds. It is shown that the formation of the interunit amide bonds in aqueous solutions of a PEC to the point of deep conversions proceeds in intracomplex form and does not lead to the crosslinking of its particles between themselves. The formation of covalent bonds in the PEC promotes significant change in its behaviour in water-salt media.

Transformation of the structure and properties of the complex of polyacrylic acid and linear polyethyleneimide on intracomplex amidation in aqueous solutions

N.V. Grishina

Papers

Intermacromolecular amidization in dilute aqueous solution of a polyelectrolyte complex of polyacrylic acid and linear polyethylene imine

Transformation of the structure and properties of the complex of polyacrylic acid and linear polyethyleneimide on intracomplex amidation in aqueous solutions