Control of pore interconnectivity in emulsion-templated porous polymers

Abstract

The applications of porous polymers obtained from polymerized high internal phase emulsions (polyHIPEs) depend on their morphology, especially interconnectivity of pores (openness). For example, an open-cell structure is required for filtration and adsorbent materials, whereas a closed-cell structure is ideal for the applications in energy storage, insulation, and encapsulation. However, the remaining challenge is to control the interconnectivity of polyHIPEs, which is influenced by the complex process of pore throat formation. In this work, we demonstrate that the formation of pore throats can be tuned through varying the attractive interdroplet interactions in the HIPE precursor. The attractive interactions among the droplets are manipulated by employing different surfactants and the refractive index (RI)-matching agent. While the depletion attraction and steric repulsion can be indirectly controlled by changing the surfactant, the van der Waals interaction is controlled by varying the amount of RI-matching agent. The scaled viscoelastic moduli of HIPEs with Laplace pressure are used to further confirm the variation of interdroplet interactions. In addition to the interdroplet interactions, we investigate the potential effect of interfacial rheology on the interconnectivity of polyHIPEs.