Blends of chitosan and poly(sodium-4-styrene sulphonate). Compatibilization by lysine and glutamic acid

Polymer blends of chitosan (CS) and poly(sodium-4-styrene sulphonate) (PSS) have been compatibilized using lysine (LYS) and glutamic acid (GLU). Blends of CS/PSS containing LYS and GLU have been studied by thermal analysis. The values of Tg for CS/PSS-LYS blends could not be detected by thermal analysis but one single Tg was found for CS/PSS-GLU blends. Thermogravimetric analysis (TGA) showed that blends decompose at lower temperatures than that of pure components. Displacements in the main absorption bands in the FT-IR spectra were not clear to discern compatibility. Atomic force microscopy (AFM) indicated that addition of lysine or glutamic acid clearly modified the compatibility of the blends. The globular domains existing in the unmodified blend changed to more or less linear and smooth crystalline domains with parallel periodicity. Dielectric analysis revealed that compatibilizer addition changed the secondary relaxation process of PSS to higher temperatures as a result of the modification on interactions. No variation on the segmental dynamics of both polymers was observed as their main relaxations remained unchanged after the addition of lysine or glutamic acid.