A Short Review on the Synthesis of Highly Open Cell PolyHIPEs: Influence of Effective Parameters on the Foam Structure and Morphology

Highly open porous polymers have been prepared by emulsion polymerization of a continuous phase of high internal phase emulsions (HIPEs). A high internal phase emulsion is an emulsion in which the internal phase, i.e. water or oil, occupies at least more than 74% of the emulsion total volume (φ=74%). Altering the HIPE stability can control the mean droplet diameter or void size of porous polymers in the range of 1-100 μm. PolyHIPEs have been used for many applications, such as preparation of catalyst supports, absorbents, membranes, and scaffolds used in tissue engineering varying the types and amounts of ingredients in the prepared emulsions. The kind of monomer, cross-linker, surfactant, and solvent in the organic phase of concentrated emulsions influences considerably the structure and properties of the polyHIPE porous materials. For instance, the porous surface area increases significantly on replacing a part of continuous oil phase with a solvent because of the phase separation occurred between polymer and solvent during polymerization. In this paper the influence of effective parameters, such as the type and concentration of the surfactant, monomer, solvent, and electrolyte on the cellular structure of PolyHIPEs has been studied.