Poly(acrylamide-co-styrene): A Macrosurfactant for Oil/Water Emulsion Templating toward Robust Macroporous Hydrogels

Large amounts of relatively expensive small-molecule surfactants, between 6 and 25%, are typically required for the formulation of oil/water high or medium internal phase emulsion (H/MIPE) templates. We synthesized an amphiphilic “macrosurfactant” copolymer poly(acrylamide-co-styrene) via micellar polymerization. As-synthesized poly(acrylamide-co-styrene) still associated with 0.01 wt % cetyltrimethylammonium bromide (CTAB) can be used to produce stable toluene or cyclohexane-in-water H/MIPEs already at concentrations of 0.1 wt %. Emulsion templates containing 2-hydroxyethyl methacrylate (HEMA) and N,N-methylenebis(acrylamide) (MBAm) in the aqueous continuous phase can be polymerized to produce macroporous poly(HEMA-co-MBAm)M/HIPEs. Our poly(HEMA-co-MBAm)M/HIPEs synthesized in templates stabilized with much lower emulsifier content were mechanically more robust, in dry and swollen state, as compared with poly(HEMA-co-MBAm)HIPEs reported in the literature.