Tristar 2 plus surface area and porosity analyzer

The synthesized materials were characterized by powder X-ray diffraction (PXRD), transmission electron microscopy (TEM) and N₂ adsorption-desorption analysis. PXRD measurements were obtained using a Bruker AXS D8 Advance diffractometer equipped with CuKα radiation and working at 40 kV/40 mA. PXRD measurements were performed at high-angle (2θ = 15°–68°) and low-angle range (2θ = 1.3°–8.3°). TEM images were taken on a 100 kV JEOL JEM-1010 microscope operated with AMT image capture engine software. TEM samples were prepared by adding 10 µl of nanoparticles suspended in distilled water onto carbon-coated copper grids. The statistical analysis of the data obtained from TEM images was performed using Origin Pro software. N₂ adsorption-desorption measurements were conducted in a TriStar II Plus surface area and porosity analyzer from Micromeritics. The specific surface area of the material was determined from the adsorption-desorption isotherm by applying the Brunauer-Emmett-Telle (BET) model. The pore volume and average pore size was estimated by using the Barret-Joyner-Halenda (BJH) model.

The surface area of mPEG-grafted silica particles was determined in order to compare the adsorption capacity of mPEG-grafted silica particles and commonly used polymeric adsorbents without incorporation of the surface area effect. Surface areas and pore volumes of bare and mPEG-grafted silica particles were estimated by nitrogen (N₂) gas physisorption analysis with Micromeritics TriStar II PLUS Surface Area and Porosity Analyzer (Norcross, GA, USA). All samples were degassed at 40 °C under a vacuum of 0.05–0.1 mbar for 18 h. N₂ gas adsorption studies were performed at 77 K and in the partial pressure range of p/p^o = 0.0001 to 0.99. Surface area and pore volumes were estimated by N₂ adsorption using the Brunauer–Emmett–Teller (BET) method [57 (link)].