Diffusion of polyethylene oxide in montmorillonite : single molecule study of polymer nanocomposite

Abstract

The behavior of Polyethylene Oxide (PEO) in the absence and presence of Montmorillonite (MMT, a clay silicate mineral) was studied using Wide Field Fluorescence Microscopy in single molecule level. In the absence of MMT, crystallization of PEO occurred. PEO moved faster in the amorphous region but it moved slowly near the crystal as reflected by the comparison of diffusion coefficient in both regions. Slower diffusion was expected due to the presence of depletion zone near the crystal which was confirmed by AFM measurement. The seaweed-like shape of the crystal was explained using diffusion limited aggregation mechanism. In the presence of MMT, PEO was intercalated into MMT. This intercalation resulted in the longer interlayer distance which was confirmed by the shift of 2 to lower angle in X-Ray Diffractogram. Inside MMT, PEO was found to diffuse much faster as compared to the motion of PEO in amorphous zone. A possible explanation for this is that the PEO experienced high Coulombic repulsion inside MMT. All the phenomena may play important role in the development of PEO/MMT-based lithium-rechargeable battery.