Nanoscale distribution and segregation of midblock-selective co-penetrants in ABA triblock copolymer lamellae

Abstract

In addition to their attractive and tunable macroscopic properties, microphase-ordered block copolymers serve as model systems capable of providing fundamental insight into the thermodynamic factors that govern the arrangement of spatially-confined molecules in soft, nanostructured environments. Of particular interest in this study is the spatial distribution of co-penetrant molecules in the design of dense polymeric materials intended for use as gas-separation membranes or responsive sensors. Here, we employ self-consistent field theory to examine the spatial distributions of two midblock-selective co-penetrants in ordered triblock copolymers exhibiting the lamellar morphology. Our results establish how differences in block copolymer incompatibility and penetrant selectivity, size and concentration affect the spatial distributions of the penetrant species, and reveal the extent to which macroscopically miscible penetrants spatially segregate due to nanoscale confinement.