Homogeneous Crystallization and Local Dynamics of Poly(ethylene Oxide) (peo) Confined To Nanoporous Alumina

Abstract

The crystallization of poly(ethylene oxide) (PEO) confined in self-ordered nanoporous alumina (AAO) containing aligned and straight cylindrical nanopores was studied as a function of molecular weight, pore size and cooling/heating rate by differential scanning calorimetry and X-ray scattering. Bulk PEO crystallizes via heterogeneous nucleation at defects and impurities whereas PEO confined to AAO crystallizes mainly via homogeneous nucleation. Molecular weight and cooling rate have a pronounced effect on the nucleation process. Dielectric spectroscopy revealed that confining PEO to AAO results in broadening of the distribution of relaxation times associated with the segmental alpha relaxation process and the secondary beta process. Dielectric loss peaks become broader with decreasing pore diameter.