In this paper, the water content of poly(ethylene oxide)-clay-alkali metal ion intercalation composites in different relative humidity was measured, and the relationship between water content and interlayer space was studied. Combined with the X-ray photoelectron spectroscopy results, the interactions of poly(ethylene oxide) (PEO), clay MMT and alkali metal ions in the composites were discussed. In the K-MMT-PEO composites, K^＋was coordinated with MMT and PEO to form stable complex, and under the conditions of different relative humidity, the water contents of the K-MMT-PEO composites were low and the interlayer space kept nearly constant. In the Na-MMT-PEO composites, Na^＋was coordinated with PEO only, water molecules could destroy this complex, and under the conditions of different relative humidity, the water contents of the Na-MMT-PEO composites were high and the interlayer space was increased with water contents.

Key words: poly(ethylene oxide), clay, complex, mechanism