Three distinct open-pore morphologies from a single particle-filled polymer blend

Abstract

Ternary mixtures composed of polyisobutylene (PIB), polyethylene oxide (PEO), and silica particles yield three distinct open-pore morphologies depending on the mixture composition: (1) pendular network (particles bonded together by menisci of PEO); (2) capillary aggregate network (particles and PEO form a combined phase with strongly solid-like properties which forms a percolating network); (3) cocontinuous morphology (silica and the PEO form a highly viscous combined phase which retards interfacial tension-driven coarsening). Remarkably, interfacial tension plays altogether different roles in stabilizing these three morphologies: stabilizing the first, not affecting the second, and destabilizing the last. The first two of these morphologies appear to be generalizable to other systems, e.g. to oil/water/particle mixtures. In all three cases, the pores do not collapse even after flow, i.e. all three porous morphologies are amenable to processing.