Capillary Imbibition of Polymer Mixtures in Nanopores

Capillary imbibition of homogeneous mixtures of entangled poly(ethylene oxide) melts in nanopores of self-ordered nanoporous alumina follows a t(1/2) dependence but contradicts the classical Lucas Washburn equation. Herein we employ reflection microscopy and self-consistent field theory (SCFT) calculations to demonstrate the faster penetration of nanopores for the shorter chains. Combined results suggest on average an 15% enrichment by the shorter chains. On top of that, SCFT shows an enrichment of the short chains near the pore surface. Possible applications in separating long and short polymer chains by the difference in imbibition speed in the absence of solvent are discussed.