An investigation of the effect of lithium montmorillonite on the structure and thermal properties of poly(ethylene oxide).

The technological importance of solid electrolyte, for which poly(ethylene oxide) (PEO) is often used, is continuously increasing. The main drawback of PEO as a solid electrolyte is its poor ionic conductivity at room temperature due to highly crystallinity, since the ionic conductivity mainly takes place in amorphous phase. Incorporation of inorganic nanophases such as nanoclays in the PEO matrix is one of the ways to decrease its crystallinity and enhance ionic conductivity. In this work, the effect of lithium montmorillonite (LiMMT) as nanofiller on crystallinity, glass transition temperature, melting temperature and thermal stability of PEO is investigated. PEO/LiMMT samples (100/0, 90/10, 80/20, 70/30, 60/40, 50/50, 40/60, 30/70, 20/80, 10/90 i 0/100 by weight) were prepared by melt intercalation method. Differential scanning calorimetry shows that the melting and glass transition temperatures of PEO are lowered as the amount of LiMMT increases. The crystallinity of PEO decreases with increasing amount of LiMMT and completely disappears between 70 and 80 mass. % of LiMMT, what is confirmed by infrared spectroscopy.Thermogravimetric analysis indicates that the degradation of PEO and PEO/LiMMT samples occurs through one degradation step and that LiMMT lowers thermal stability of PEO up to 50°C.