Multi-layered polymerized high internal phase emulsions with controllable porosity and strong interfaces

Porous elastomers possessing gradient morphology or chemistry are needed for new applications including biomaterial interfaces, additive manufacturing, and separation membranes. However, elastomers possessing a porosity gradient are often difficult to prepare requiring slow multistep synthesis techniques. In this work, layered porosity polydimethylsiloxane (PDMS)-based polymerized high internal phase emulsions (polyHIPEs) with defined interfaces have been synthesized using one-step reactions. The total porosity, pore size, and surface area of the prepared polyHIPEs are controlled by varying the volume of aqueous dispersed phase in the emulsion. Analysis of SEM images and pore size calculations of layered porosity polyHIPEs proved the emulsion patterning method did not disrupt emulsion morphology and a clear porosity interface was maintained. Total porosity values dictate the storage moduli of the polyHIPEs, where highly porous materials possess the lowest observed moduli of similar to 70-90 kPa. Tensile testing shows that the interface between two layers is mechanically robust and does not split during elongation at break experiments. This work provides a simple technique to prepare layered porosity PDMS-based polyHIPEs having up to five tunable porosity layers with strong interfaces between the layers.