PolyHIPEs are porous highly interconnected emulsion-templated polymers typically synthesized within surfactant-stabilized water-in-oil high internal phase emulsions (HIPEs). Surfactant-free polyHIPEs can be synthesized in nanoparticle-stabilized Pickering HIPEs. The effects of polymerization mechanism and locus/nature of initiation were investigated.Elastomeric polyacrylate (PA) polyHIPEs, usually synthesized using conventional free radical polymerization (organic-phase initiation or interfacial initiation), were synthesized using activators generated by electron transfer for atom-transfer radical polymerization (AGET ATRP), Figure 1a. Two different AGET ATRP systems were used, an organic-soluble initiator or an initiator anchored to nanoparticles (NP), either silica or polymer. These NPs could perform 3 functions, stabilizing the HIPEs, initiating the polymerization, and crosslinking the polymer. PolyHIPEs containing around 85 % individually encapsulated micrometer-scale water droplets with enhanced resistance to compressive deformation and to ignition upon direct exposure to a flame were synthesized. The polymerization mechanism and locus of initiation had profound effects upon the molecular structures, porous structures, and properties.A degradable polymethacrylate polyHIPE crosslinked using bis(2-methacryloyloxyethyl) disulfide (DSDMA) was synthesized using AGET ATRP with two different CuBr2 catalyst systems, a highly hydrophobic N,N-bis(2-pyridylmethyl)octadecylamine (BPMODA) ligand (Figure 1b) or a less hydrophobic 2,2'-bipyridine (bpy) ligand. The BPMODA-based system produced polyHIPEs with more uniform crosslinked networks which degraded into polymer chains with a relatively low dispersity. The bpy-based catalyst exerted less control over the polymerization and produced a non-degradable polymer.

AGET ATRP of elastomeric polyacrylate and biodegradable polymethacrylate porous polymers within high internal phase emulsions

248th National Meeting (2014)

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