Preparation of porous polymer materials using water‐in‐oil gel emulsions as templates

Abstract Water‐in‐oil gel emulsions consisting of water and n ‐butyl acrylate were successfully prepared using N ‐3‐hydroxybutylcarbonyl‐ l ‐isoleucylaminooctadecane and sorbitan monooleate (Span 80) as gelator and surfactant, respectively. Stable gel emulsions were formed using aqueous phase fractions (APFs) ranging from 10 to 90 vol%. Creaming, flocculation and coalescence were not observed. Low‐temperature polymerization of the gel emulsions with a redox initiator gave the corresponding low‐density, highly porous poly( n ‐butyl acrylate)s (PBAs). The microstructures of the PBAs were observed using scanning electron microscopy. All the porous PBAs comprised numerous spherical structures whose sizes could be controlled by adjusting the gel emulsion APF. The densities and porosities of the porous PBAs decreased and increased, respectively, with increasing APF. The absorption capacities of the porous PBAs in organic solvents were studied. The porous PBAs selectively absorbed kerosene from water instantly and the kerosene could then be recovered by physical compression of the PBAs. Further porous polymers were prepared from gel emulsions containing styrene, methyl methacrylate (MMA) or 2‐ethylhexyl acrylate (EHA) as continuous oil phases. The order of absorption capacity and swelling ratio in kerosene was poly(EHA) > PBA ≫ poly(MMA). Porous copolymers were also prepared from gel emulsions containing a mixture of EHA and MMA as the oil phase. Their absorption and swelling in liquids could be controlled by changing the ratio of EHA and MMA in the gel emulsions. poly(EHA‐ co ‐MMA) (6:4) was the best polymer when absorption capacity, swelling ratio and durability were simultaneously considered. © 2018 Society of Chemical Industry