Miscibility of chitosan/poly(ethylene oxide) blends and effect of doping alkali and alkali earth metal ions on chitosan/PEO interaction

The miscibility of Chitosan (CS) and poly(ethylene oxide) (PEO) in their blends and the effect of K+ and Ca2+ doping on the CS/PEO interaction have been investigated in this work. CS and PEO appeared to be miscible and the DSC analysis suggested the Flory–Huggins interaction parameter χAB to be −0.21. Doping of K+ and Ca2+ into the CS/PEO blend matrix enhanced the cooperative interaction between CS and PEO and this enhancement was larger for Ca2+ than for K+. The difference between Ca2+ and K+ possibly reflects a stronger multi-valence interaction of Ca2+ with the amino and hydroxyl groups of CS as well as the ether groups of PEO to form a stable CS/Ca2+/PEO complex and a less significant interaction of K+, as suggested by DSC, WAXD and FTIR results. MD simulations clearly indicated the correlation between the dynamic behavior and the interaction of K+ and Ca2+ in the CS/PEO blend matrix.