Preparation of highly cross-linked hydrophilic porous microspheres poly(N,N′-methylenebisacrylamide) and poly(N,N′-methylenebisacrylamide-co-acrylic acid) with an application on the removal of cadmium

An effective polymerization system was developed for the synthesis of highly cross-linked hydrophilic monodispersed microspheres with both the micropores and mesopores inside. A series of poly( N , N ′-methylenebisacrylamide) (PMBA) microspheres with the diameters ranging from 100 to 300 nm were synthesized by distillation precipitation polymerization with N , N -dimethylacetamide (DMAC) as the porogen, acetonitrile as the solvent, and MBA as the cross-linker and monomer. The particle size, morphology, and porosity varied according to the variation of the DMAC content. The porosity was determined by physical adsorption of nitrogen, and reached the maximum at 7.5 vol% of DMAC with the specific surface area at 135.8 m 2 g −1 and the total pore volume at 0.43 cm 3 g −1 . The porous and hydrophilic microspheres showed excellent swelling property in water and adsorption property for the Cd(II) in aqueous solution. Meanwhile, carboxylic groups were incorporated into the porous microspheres to achieve porous poly( N , N ′-methylenebisacrylamide- co -acrylic acid) (P (MBA- co -AA)-P), which exhibited obvious synergies of the pores and functional groups on the adsorption and provided a perspective application of the Cd(II) removal.