engleski

Importance of the precursor layer for tuning the properties of chitosan/carboxymethyl cellulose polyelectrolyte multilayers

Polyelectrolyte multilayers (PEMs) composed of chitosan (CS) and carboxymethyl cellulose (CMC), two natural polyelectrolytes, have been recently getting attention as environmentally safe and non-toxic food coatings. Traditionally, these materials are prepared using layerby-layer (LbL) deposition method. As CS and CMC have low initial adsorption to a targeted surface during LbL build-up, the addition of another polyelectrolyte as the first layer, a precursor, plays an important role. Usually, poly(ethyleneimine) (PEI) is used as such layer but its toxicity to both bacterial and, especially, human cells is concerning for the application of these films. The aim of this study was to provide an alternative, biocompatible and environmentally safe precursor layer to replace PEI. Moreover, we studied the effect of addition of NaCl to the polyelectrolyte build-up solutions on the surface properties of all examined nanofilms. The main methods used in this study were ellipsometry, for monitoring the film thickness and growth during the build-up process, and atomic force microscopy (AFM), which was used to determine surface morphology, film thickness and roughness of the prepared nanofilm. Our results confirmed that using concentrated solution of chitosan as a precursor layer is a viable alternative to PEI. This method produces nanofilms which have double the thickness of films prepared with PEI, but this is also followed by an increase in surface roughness. Finally, the addition of NaCl strongly influences the properties of the films depending on its concentration in polyelectrolyte solutions used during the build-up process.

Polyelectrolyte multilayers ; Ellipsometry ; Atomic force microscopy ; First layer ; Surface properties

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