Synthesis and thermal characterization of porous polymeric microspheres functionalized with thiol groups

The paper presents a method of the preparation and functionalization of polymer microspheres consisting of glycidyl methacrylate (GMA) and crosslinking agents: 1,4-dimethacryloyloxybenzene (1,4DMB) and trimethylolpropane trimethacrylate (TRIM). Poly(GMA-co-1,4DMB) and poly(GMA-co-TRIM) microspheres were obtained by seed swelling polymerization. To introduce thiol groups into the microspheres structure, the reaction with thiocarboxylic acids was performed. The chemical structure of parent and modified microspheres was confirmed by FTIR and Raman spectroscopy. Elemental composition of microspheres after functionalization was determined by elemental analysis. The analysis showed the percentage of sulfur in the range of 2.78-4.51%, which corresponds to a concentration of thiol group in the range of 0.87-1.41 mmol g(-1). Additionally, the porous structure of the copolymers was investigated using the low-temperature nitrogen adsorption-desorption method. The starting microspheres are characterized by a specific surface in the range of 150-160 m(2) g(-1), whereas functionalized copolymers indicate slightly lower surface area, of about 130 m(2) g(-1). The thermal stability of the materials was determined by the method of differential scanning calorimetry and thermogravimetric analysis. The course of the thermal degradation under oxidative conditions of modified microspheres is different from the starting copolymers. The functionalized microspheres showed much higher thermal stability (approximately 270 degrees C) compared to the starting microspheres (230-250 degrees C).