SYNTHESIS AND CHARACTERIZATION OF POROUS PARTICULATE POLYIMIDES

Porous particulate polyimides have been prepared by four suspension po lycondensation procedures. The first group were linear polyimides prep ared in suspension in liquid paraffin from a poly(amido acid) pre-poly mer solution. Groups two to four were crosslinked using a tetraamine c omponent. The first of these employed a linear poly(amido acid) pre-po lymer solution and crosslinking was achieved in the suspension second step. The second employed a branched, poly(amido acid) pre-polymer sol ution and crosslinking was completed in suspension. The third was a on e-pot procedure which did not utilise a pre-polymer. Instead, all mono mer components and solvent were dispersed in paraffin oil and condensa tion and crosslinking were achieved in suspension. Imidisation was ind uced using acetic anhydride and pyridine, and suspensions were stabili sed using a paraffin oil soluble surface active polymer. Dipolar aprot ic solvents functioned as porogens, and particulates with N2 BET surfa ce areas up to ca. 90 m2 g-1 were prepared.