Nanoporous, hypercrosslinked polypyrroles: effect of crosslinking moiety on pore size and selective gas adsorption

摘要

Nanoporous, hypercrosslinked polypyrroles with surface areas of up to 720 m~2 g~(-1) have been prepared; their pore sizes and gas adsorption selectivities were controlled by varying the size of the crosslinking units.rnNanoporous organic polymers have recently been studied for a variety of applications, including gas sorption and hydrogen storage. Of the methods available for the preparation of porous polymers, hypercrosslinking has proven to be among the most versatile. In hypercrosslinking, a precursor material is dissolved or swollen in a thermodynamically good solvent and a crosslinking reaction is used to lock the polymer in a state that resembles closely its solvated state. When the solvent is removed, the space that it leaves behind becomes pores. In this report we have explored the use of this strategy to prepare nanoporous polypyrroles with large surface areas, and explored a possible link between the sizes of the cross-linking units and that of the resulting pores. Hypercrosslinked polymers have been touted for their potential in separations, the adsorption of organic compounds, the storage of gases such as hydrogen and methane in their supercritical state, as electrodes and as media for chromatography. Porous polypyrroles have found applications in electronics as electrodes for batteries or as capacitors. Porosity is typically imparted to polypyrroles via a templating process utilizing nanoporous silicon or carbons. In addition to the importance of surface area in applications involving reactions which are kinetically limited, it has been suggested that the conductivity of doped polypyrrolc is a function of its surfacernarea.