Web Release Date: May 18,
Reversible De-Intercalation and Intercalation Induced by Polymer Crystallization and Melting in a Poly(ethylene oxide)/Organoclay Nanocomposite
and
Polymer Program, Institute of Materials Science and Department of Chemical Engineering, The University of Connecticut, Storrs, Connecticut 06269-3136, and Chemistry Department, State University of New York at Stony Brook, Stony Brook, New York 11794-3400
Received November 27, 2004
In Final Form: April 30, 2005
Abstract:
Semicrystalline polymer/layered silicate nanocomposites were prepared by solution blending of a low molecular weight poly(ethylene oxide) (PEO) with an organically modified montmorillonite, Cloisite 10A (C10A). The intercalation morphology was studied by temperature-dependent synchrotron wide-angle X-ray diffraction (WAXD). Unlike PEO homopolymers, significant secondary crystallization was observed in the PEO/C10A nanocomposites. Reversible de-intercalation and intercalation processes were detected during secondary crystallization and subsequent melting of secondary crystals. On the basis of two-dimensional WAXD results on oriented samples, an interphase layer between the silicate primary particles and PEO lamellar crystals was proposed. Secondary PEO crystallization in the interphase regions was inferred to be the primary driving force for polymer chains to diffuse out of the silicate gallery. This study provided a useful method to investigate polymer diffusion in nanoconfined spaces, which can be controlled by PEO secondary crystallization and melting outside the silicate gallery.
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