Various Characteristics of Nanosized V₂O₅/TiO₂and MoO₃–Modified V₂O₅/TiO₂Catalytic Systems Used in Redox-Initiated Polymerization of Methyl Methacrylate

Abstract

Various samples of nanosized V 2 O 5 (2-20 wt%)=TiO 2 catalytic systems (of particle sizes ranged between 5 and 50 nm were characterized. The effect of addition of MoO 3 (3-9 wt%), in different sequences, was followed up in view of competing interactions with titania surface. Characterization was performed through XRD, FTIR, BET, and TEM techniques. Catalytic activity of prepared samples was tested in redox-initiated polymerization of methyl methacrylate, in presence of NaHSO 3 cocatalyst. The proposed polymerization mechanism indicated participation of HSO Á 3 radicals, primarily generated on a TiO 2 surface, with V 5þ =V 4þ and=or Mo 6þ =Mo 5þ redox pairs to form active radical species with the monomer. In all cases, extremely high yields of reasonably high molecular weight polymers, of syndiotactic-structure, were functions of catalyst nanosized nature, rapid redox-initiation steps, and mode of MoO 3 addition.Keywords MoO 3 -modified V 2 O 5 =TiO 2 , redox-initiated polymerization, methyl methacrylate, V 2 O 5 =TiO 2