Effect of starch type on miscibility in poly(ethylene oxide) (PEO)/starch blends and cytotoxicity assays

This study reports results on the miscibility of polymer blends based on PEO and different starches (unmodified, cationic, and hydrophobic) and their respective cytotoxicity. Films of PEO/starch blends at different weight ratios (95/05, 90/10, 80/20, 70/30, 65/35, and 60/40), as well as films of pure PEO as control, were prepared by casting methodology. Several techniques, such as SEM, WAXS, FTIR, and FT-Raman spectroscopy were used in this study for evaluating blend miscibility. The results revealed that the miscibility of such blends is dependent on the type of starch used. Regarding the PEO/unmodified starch blends, it was concluded that the system is miscible in the ratio range from 90/10 to 65/35. Although the PEO/hydrophobic starch blends are miscible in all the studied range, blends of PEO and cationic starch are immiscible, regardless the blend ratio. The different samples presented distinct cytotoxic behaviors. PEO and hydrophobic starch presented no relevant toxicity (CC50/72 > 2.5 mg/mL). Otherwise, the cationic starch was the most harmful for the cells. The blends presented cytotoxicity values between those of PEO and cationic starch.