THE STRUCTURAL-ANALYSIS OF CARDO SILICONE POLYIMIDES BY HIGH-RESOLUTION SOLID-STATE C-13, N-15 AND SI-29 NMR

It is well-known that polymers containing a fluorene moiety (so-called 'Cardo-type polymers') have high them;al stability, good mechanical p roperties and excellent solubility in common organic solvents. For the benefit of the full use of these polyimides in industrial application s, cross-linked Cardo silicone polyimides, which have both high therma l stability and high resistivity to organic solvents, were designed. T he cross-link density was determined by solid-state C-13 and Si-29 NMR because no other direct method for the determination of the cross-lin k density is available. Furthermore, natural abundance CPMAS C-13 and N-15 NMR measurements were made for three different forms of Cardo sil icone polyimides which exhibit a high oxygen permselective property. A n explanation for the gas separation mechanism is given. (C) 1998 Else vier Science B.V.