113 research outputs found
PPEGMEMA-based cationic copolymers designed for layer-by-layer assembly
We have synthesized three PPEGMEMA-based cationic copolymers with similar amine contents but with systematic variation in the average length of the PEG side chains. The positively charged copolymers were paired with alginate to fabricate layer-by-layer assembled multilayered films. It was demonstrated that the polymeric design, in terms of the systematic variation in the average length of the PEG units, affects the polyelectrolyte multilayer growth mechanism and can be used to tune the structural properties and the water content of the layers. In addition, by partial cross-linking of the amine groups present in the copolymer backbone, disintegration of the film induced by pH changes was prevented. Finally, it was demonstrated how the cross-linked multilayered film can exhibit cationic, zwitterionic and anionic properties depending on the pH value and how these changes are associated with swelling, layer contraction and changes in water content
Structural Investigation of a Self-Cross-Linked Chitosan/Alginate Dialdehyde Multilayered Film with in Situ QCM-D and Spectroscopic Ellipsometry
A chitosan/alginate
dialdehyde multilayered film
was fabricated using the layer-by-layer assembly method. Besides electrostatic
interaction that promotes alternate adsorption of the oppositely charged
polyelectrolytes, the Schiff base reaction between the amine groups
on chitosan and the aldehyde groups on alginate dialdehyde provides
a covalently cross-linked film, which after reduction by sodium cyanoborohydride
is stable under both acidic and alkaline conditions. Moreover, the
cross-linked film is responsive to changes in pH and addition of multivalent
salts. The structural properties of the multilayered film such as
thickness, refractive index, and water content were examined using
simultaneous quartz crystal microbalance with dissipation monitoring
and spectroscopic ellipsometry
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