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Polymers oxidation with VO(acac)2 complex

2000; Elsevier BV; Volume: 57; Issue: 3-4 Linguagem: Inglês

10.1016/s0920-5861(99)00332-6

1873-4308

Annelise Engel Gerbase, José Ribeiro Gregório, Márcia Martinelli, Maria Luíza Ambros von Holleben, Marly Antônia Maldaner Jacobi, L. de Lucca Freitas, Carmen Iara Walter Calcagno, Ana Néry Furlan Mendes, Marcia Lopes Pires,

Metal-Catalyzed Oxygenation Mechanisms

Abstract The introduction of epoxy groups in the polymer backbone is one of the most promising methods of modifying polydienes. In this work the performance of the classical catalytic system VO(acac) 2 / tert -butylhydroperoxide was evaluated for the epoxidation of polydienes. The polymers investigated were a hydroxylated poly(butadiene), two polybutadienes with high and with low 1,4-content, a poly(isoprene), and a styrene–butadiene copolymer. The epoxidized polymers were characterized by IR, 1 H and 13 C NMR and GPC techniques. The vanadium system was active for the epoxidation reaction and the reactivity decreases in the order HTPB>PI>1,4-PB>1,2-PB∼SBR. The occurrence of secondary reactions to low extension could be detected by the presence of hydroxyl, carbonyl and alcohol signals in the spectra of epoxidized polymers. Incomplete mass recovery (70–90%) was observed probably due to the chain degradation or modification of the polymer polarity.