Manipulating Crystal Orientation of Poly(ethylene oxide) by Nanopores

Abstract

The confined crystallization behavior of a low molecular weight monodisperse polyethylene oxide (PEO) in anodic alumina oxide (AAO) templates was investigated. Homogeneous nucleation of polymer in AAO templates was confirmed. Within AAO with diameter larger than the contour length of PEO chains, the "kinetics selective growth" crystallization mechanism was confirmed based on the observation that the chain axis preferentially aligned perpendicular to the pore axis. However, when AAO diameter further decreases to a value smaller than the contour length of PEO, unique orientation with chain axis aligned parallel to the pore axis was observed for the first time. The results were discussed based on the competition between thermodynamics and kinetics during the crystallization process.