Crystallization Behavior of Poly(ethylene oxide) in the Presence of Na⁺ Montmorillonite Fillers

Abstract

The crystallization behavior of poly(ethylene oxide) (PEO) was studied in the presence of an inorganic filler surface (sodium montmorillonite) with DSC, as well as isothermal cross-polarization optical microscopy. Crystallization of PEO is found to be inhibited, exhibiting a decrease of spherulite growth rate and crystallization temperature. However, the overall crystallization rate increases with silicate loading as a result of extra nucleation sites, which occur in the bulk PEO matrix (i.e., far from the silicate surfaces). PEO differs from other systems, where crystallinity is typically enhanced next to such surfaces, in that the polymer is amorphized near the montmorillonite surfaces. This behavior is attributed to the specific way that PEO interacts with Na+ montmorillonite, where strong coordination of PEO to the surface Na+ cations promotes noncrystalline (ether crown) PEO conformations.