Poly(glycidyl methacrylate-co-1,4-dimethacryloyloxybenzene) monodisperse microspheres - synthesis, characterization and application as chromatographic packings in RP-HPLC

The study describes the synthesis of porous microspheres with glycidyl methacrylate (GMA) and 1,4-dimethacryloyloxybenzene (DMB) using the seed swelling polymerization. As a shape template the polystyrene (PS) seed obtained via the dispersion polymerization was used. Oxirane, esters and aromatic groups are present in the structure of copolymers. Changing the reaction mixture composition – the amounts of crosslinking monomer and PS seed, almost monosized poly(GMA-co-DMB) microspheres of the diameters in the range of 8.20 μm to 11.61 μm and highly developed porous structure with specific surface area (SBET) up to 353 m2/g were obtained. The pore size distribution and the volume of pores measured for the copolymer in the dry and the swollen states differ. In the dry state in the internal copolymer structure mesopores were observed whereas in the swollen state additionally micro- and macropores appeared. The copolymer obtained with the equimolar mixture of monomers was applied as the column packing material and tested in the reverse-phase HPLC. The isocratic separation of alkylbenzenes was achieved with satisfactory resolution using the 100 × 4.6 mm i.d. column with the acetonitrile/phosphate buffer mobile phase. The theoretical plate numbers up to 12,000 were obtained for benzene as the analyte. Using the retention indices for the test compounds it was found that the retention mechanism on the studied copolymer is the sum of π-π hydrophobic interactions, dipole interactions and to a smaller extent of hydrogen acceptance interactions rather than hydrogen donation interactions.