ESR study of hypercrosslinked polystyrene carbonizate—organic solvent—oxygen systems

Abstract

Carbonizates of hypercrosslinked polystyrenes were studied by ESR spectroscopy. Conditions for preparation of paramagnetic carbon sorbents used as oxygen sensors were determined. These sorbents are characterized by an intense narrow ESR singlet for air desorption by pyridine, glycerol, ethanol, methanol, and water. For the carbonizates of nonionogenic biporous hypercrosslinked polystyrenes (I) or sulfonic cation-exchange resins based on biporous hypercrosslinked polystyrenes (II), the ESR line width decreases from 10 G in oxygen to 0.4–1.2 G (0.4 G for glycerol) upon solvent introduction, and the signal amplitude increases by two-three orders of magnitude. When solvents with the linear structure of molecules (alkanes, their mono-and dichlorosubstituted derivatives, alcohols) are introduced, the ESR line can decrease to 2.3±0.3 G. Carbonizates I and II obtained by pyrolysis at temperatures 580–620 °C possess a large internal surface (up to 680 m2 g−1) and contain packets of condensed aromatic polycycles with delocalized π-electrons.