title: 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.
authors.affiliation: Polymer and Composite Engineering (PaCE) Group, Department of Chemical Engineering, Imperial College London, South Kensington Campus, London, United Kingdom.
authors.forename: Ling L C
authors.initials: LL
authors.lastname: Wong
authors.forename: Pedro M Baiz
authors.initials: PM
authors.lastname: Villafranca
authors.forename: Angelika
authors.initials: A
authors.lastname: Menner
authors.forename: Alexander
authors.initials: A
authors.lastname: Bismarck
mesh_terms: D004655:Emulsions / Q000138:chemical synthesis / Q000737:chemistry; D010316:Particle Size; D058105:Polymerization; D011108:Polymers / Q000138:chemical synthesis* / Q000737:chemistry; D016062:Porosity; D013499:Surface Properties; D013501:Surface-Active Agents / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D004655:Emulsions; D011108:Polymers; D013501:Surface-Active Agents