Synthesis and characterisation of porous particulate polyimides

Abstract

Porous particulate polyimides have been prepared by four suspension polycondensation procedures. The first group were linear polyimides prepared in suspension in liquid paraffin from a poly(amido acid) pre-polymer solution. Groups two to four were crosslinked using a tetraamine component. The first of these employed a linear poly(amido acid) pre-polymer solution and crosslinking was achieved in the suspension second step. The second employed a branched poly(amido acid) pre-polymer solution and crosslinking was completed in suspension. The third was a one-pot procedure which did not utilise a pre-polymer. Instead, all monomer components and solvent were dispersed in paraffin oil and condensation and crosslinking were achieved in suspension. Imidisation was induced using acetic anhydride and pyridine, and suspensions were stabilised using a paraffin oil soluble surface active polymer. Dipolar aprotic solvents functioned as porogens, and particulates with N₂ BET surface areas up to ca., 90 m² g^–1 were prepared.