The continuous phase of high internal phase emulsions (HIPEs) can be polymerized to produce highly porous materials, known as polyHIPEs. The aim of this work was to synthesize polyHIPE microfiltration membranes having a hydrophobic bulk and a hydrophilic surface to enhance their performance. Therefore, in situ functionalization was performed through interfacial copolymerization of a hydrophobic monomer (butyl acrylate) in the continuous phase with a hydrophilic monomer (sodium acrylate) in the disperse phase. The functionalization of polyHIPEs was studied by using conductometric titration and Fourier transform IR spectroscopy. We show that the surface charge density of poly(butyl acrylate)-based polyHIPEs can be controlled by varying the concentration of sodium acrylate in the disperse phase. PolyHIPE microfiltration membranes have higher intrinsic permeability (around 1.31 × 10 −8 m 2 ) in comparison to conventional microfiltration membranes. The interfacial copolymerization of sodium acrylate increases the permeability of microfiltration membranes. In addition, the rejection of polyHIPE microfiltration membranes was studied for the separation of microalgae. Characterization techniques Scanning electron microscopyThe morphology of the polyHIPEs was studied via a scanning electron microscope (S-3400N Type II, Hitachi High-Technologies Corp.). The samples were fractured in liquid nitrogen and sputter Polym Int 2019; 68: 1378-1386

The current study aims to provide an outlook on the nanoemulsions templating method by discussing their potentials to produce different polymers and evaluating challenges that might be posed during emulsification and polymerization. Tunable properties such as controllable droplet size, volume fraction, composition, and interdroplet interactions provide tools for controlling the structure of nanoemulsions and nanoemulsion-templated polymers. Therefore, these properties along with a phase diagram including the liquid, gel, attractive glass, and repulsive glass states of nanoemulsions are discussed in this Perspective. Although the synthesis of nanoparticles is the main application of nanoemulsion templating in the literature, polymerization of monomers in the continuous phase of nanoemulsions has potential to expand their applications and produce complex structured porous polymers. Nanoemulsion characteristics can also be tuned to produce porous polymers with desirable properties. This Perspective also looks at multiple nanoemulsions with multi-phase droplets, which recently have become of great interest for producing nanoparticles with complex morphologies. Multiple nanoemulsions and their templating provide new avenues for certain applications particularly in pharmaceutical and nanotechnology industries.

In this work, we investigate the effect of interdroplet interaction on the rheological behavior of oil-in-water emulsions within a range of macro- to nano-droplet sizes and various volume fractions from dilute to concentrated regimes. We determine the total interdroplet interaction from electrostatic, van der Waals, and depletion attraction contributions. At constant surfactant concentration, the depth of attractive potential is much higher than kBT for submicron emulsions and macroemulsions, whereas it is on the order of thermal energy for nanoemulsions. Thus, as the droplet size decreases in systems with considerable yield stress below jamming transition, the emulsions undergo a gel-to-glass transition. The yield strain ranges of gel and glassy systems overlap, although the droplets in gels undergo the dissipative rearrangement before macroscopic translational motion.

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Porous polymerized high internal phase emulsion (polyHIPE) monoliths are synthesized by using Span 80 with different cosurfactants. The results reveal that the void size can be reduced by employing cosurfactants, except for Tween 20. Furthermore, the openness of polyHIPEs changes by using different cosurfactants or by varying their concentration. To further investigate the effect of cosurfactants, we perform rheology measurements on the interface of the aqueous and oil phase. This study demonstrates the important role of interfacial elasticity in the successful preparation of polyHIPEs with different morphologies. Additionally, this study suggests that the increase in interfacial elasticity hinders the formation of interconnections between pores, known as windows. Finally, the compression test is performed to investigate the effect of the pore structure on the mechanical properties.