Synthesis and characterization of porous copolymers of 2-hydroxyethyl methacrylate with ethylene glycol dimethacrylate

The present study describes the synthesis and characterization of porous copolymers of 2-hydroxyethyl methacrylate (HEMA) cross-linked ethylene glycol dimethacrylate (EGDMA). They were synthesized in the regular microspheric shape via suspension-emulsion polymerization using toluene as a porogen. Different molar ratios of monomers (1:3, 1:2, 1:1, 2:1, 3:1) were applied in the syntheses. It was interesting to check if any of the above mentioned ratios can provide materials with an advantageous proportion of hydroxyl groups to the value of specific surface area. Additionally, we aimed into polymers with a good thermal stability. The obtained materials were characterized by elemental analysis, FTIR-ATR spectroscopy, hydroxyl value (HV), low-temperature nitrogen adsorption-desorption method, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). It was found that by tuning the molar ratio of functional monomer to the cross-linker, it is possible to obtain copolymers with developed internal structure and a high HV. The optimal results were achieved for HEMA-co-EGDMA_1:2 (specific surface area: 111 m(2)/g, HV: 117 mg KOH/g). Furthermore, all the synthesized copolymers show a good thermal stability both in helium and air atmospheres. Their temperatures of 5% mass losses are over 230 degrees C. The presented data indicate that the synthesized microspheres can be potentially use in various adsorption techniques including high temperature processes.