Hierarchical Polymerized High Internal Phase Emulsions Synthesized from Surfactant-Stabilized Emulsion Templates

Abstract

In building construction, structural elements, such as lattice girders, are positioned specifically to support the mainframe of a building. This arrangement provides additional structural hierarchy, facilitating the transfer of load to its foundation while keeping the building weight down. We applied the same concept when synthesizing hierarchical open-celled macroporous polymers from high internal phase emulsion (HIPE) templates stabilized by varying concentrations of a polymeric non-ionic surfactant from 0.75 to 20 w/vol %. These hierarchical poly(merized)HIPEs have multimodally distributed pores, which are efficiently arranged to enhance the load transfer mechanism in the polymer foam. As a result, hierarchical polyHIPEs produced from HIPEs stabilized by 5 vol % surfactant showed a 93% improvement in Young's moduli compared to conventional polyHIPEs produced from HIPEs stabilized by 20 vol % of surfactant with the same porosity of 84%. The finite element method (FEM) was used to determine the effect of pore hierarchy on the mechanical performance of porous polymers under small periodic compressions. Results from the FEM showed a clear improvement in Young's moduli for simulated hierarchical porous geometries. This methodology could be further adapted as a predictive tool to determine the influence of hierarchy on the mechanical properties of a range of porous materials.

Highly permeable macroporous polymers via controlled agitation of emulsion templates

“…This is caused by a higher degree coalescence of the template emulsion before polymerization, creating pores which were much larger than those obtained at the end of agitation this makes the final structure more irregular. A similar result was found by Wong et al [31]. Similarly air bubbles entrained into the emulsion will also be larger for a shorter agitation time of the emulsion template.…”

“…This would lead to much larger pores than the original droplet size in the emulsion immediately after blending making it much less trivial to predict pore size of macroporous polymers produced by emulsion templating. Ostwald ripening (coarsening) [29] can also occur within the system leading to a hierarchal pore system, in which much larger pores are embedded in between much smaller ones [30,31]. The rate of coalescence in emulsions was observed to increase at elevated temperatures [32] needed to typically initiate a free-radical polymerization.…”

Synthesis and properties of polystyrene-based polyHIPEs reinforced with quadruple hydrogen bond functionality

“…5d, it can be concluded that there were some pins in the matrix of polyHIPE-3, and those pins may be formed by the dimerization of UPy groups. Multimodal pore size distribution has an important effect on mechanical strength [34]. PolyHIPE with an optimal packing configuration may have good mechanical properties.…”

“…Bismarck's group has done many work in this field [29][30][31][32][33][34]. The polyHIPEs were synthesized from HIPEs containing styrene (St, served as monomer) and divinylbenzene (DVB, employed as crosslinker) as the external phase.…”

Monolithic supermacroporous hydrogel prepared from high internal phase emulsions (HIPEs) for fast removal of Cu 2+ and Pb 2+

“…Among the commonly used methods including direct templating, block copolymer selfassembly, and direct synthesis [27,28], freeze-drying is the simplest way to prepare aligned porous inorganic, organic and composite materials [29][30][31]20], but the pore size and pore structure can't be easily tuned via freeze-drying. From an application perspective, the direct templating methodology is a versatile approach to product highly porous polymers with connected pores and tunable pore size [32][33][34], such as high internal phase emulsion (HIPEs) technique. This is a biphasic system with the volume fraction of the discontinuous phase as high as above 74.05%.…”