Polybenzimidazole as a Promising Support for Metal Catalysis: Morphology and Molecular Accessibility in the Dry and Swollen State

• Published in: Chemistry : a European journal 2000-03, Vol.6 (5), p.794-799
• Main Authors: D'Archivio, A. A., Galantini, L., Biffis, A., Jeřábek, K., Corain, B.
• Format: Article
• Language: English
• Subjects: catalyst supports; catalysts; polybenzimidazole beads
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/(SICI)1521-3765(20000303)6:5<794::AID-CHEM794>3.0.CO;2-X

Polybenzimidazole (PBI) in beaded form (250‐500 μm) has been characterized in the dry state by scanning electron microscopy (SEM), BET, and nitrogen porosimetry. In the swollen state, it has been characterized by inverse steric exclusion chromatography (ISEC) in tetrahydrofuran, toluene, and water, by ESR of TEMPONE (2,2,6,6‐tetramethyl‐4‐oxo‐1‐oxypiperidine), and pulse field gradient spin echo (PGSE) NMR spectroscopy, toluene, in tetrahydrofuran, ethanol and water. The dry‐state results are in good agreement with the ISEC results obtained in tetrahydrofuran, toluene, and water with regard to the 40–;80 nm macroporosity. The swelling‐dependent surface area and pore volume detected by ISEC in toluene and water reveal the amphiphilic nature of PBI. Polibenzimidazolo, in forma di sferule con diametro 250–;500 μm e un grado di funzionalizzazione pari a 5.6 meq g−1, viene caratterizzato allo stato secco tramite SEM, BET e porosimetria ad azoto, tramite cromatografia ISEC (inverse steric exclusion chromatography) allo stato rigonfiato in tetraidrofurano, toluene ed acqua, tramite la registrazione dello spettro ESR della sonda paramagnetica TEMPONE (2,2,6,6‐tetrametil‐4‐osso‐1‐ossipiperidina) in toluene tetraidrofurano, etanolo e acqua e tramite spettrometria PGSE‐NMR in questa stessa terna di solventi. I risultati delle analisi eseguite nello stato secco concordano apprezzabilmente con i risultati ISEC ottenuti in tetraidrofurano, toluene ed acqua con specifico riferimento alla macroporositá di 40–;80 nm. I valori di area superficiale e di porosita' determinati tramite ISEC dopo rigonfiamento in toluene ed acqua, rivelano un carattere alquanto amfifilico del PBI. Perlový polybenzimidazol (průměr 250–;500 μm; stupeň funkcionalizace 5.6 meq g−1) byl v suchém stavu charakterizován rastrovací elektronovou mikroskopií a adsorpcí dusíku. Ve zbotnalém stavu inversní sterickou exklusní chromatografií (ISEC) v prostředí tetrahydrofuranu, toluenu a ve vodě a dále pomocí ESR s TEMPONE (2,2,6,6‐tetramethyl‐4‐oxo‐1‐oxypiperidin) a PGSE‐NMR v toluenu, tetrahydrofuranu, ethanolu a ve vodě. Jak výsledky charakterizace v suchém stavu, tak i ISEC v#139;tetrahydrofuranu, toluenu i vodě shodně indikovaly přítomnost makropórů o průměru 40 a 80 nm. Botnáním rozvinutý specifický povrch a objem pórů detekovaný ISEC v toluenu a vodě ukazuje na poněkud amfifilický charakter PBI.