Various Characteristics of Nanosized V₂O₅/TiO₂ and MoO₃–Modified V₂O₅/TiO₂ Catalytic Systems Used in Redox-Initiated Polymerization of Methyl Methacrylate

Abstract

Various samples of nanosized V₂O₅ (2–20 wt%)/TiO₂ catalytic systems (of particle sizes ranged between 5 and 50 nm were characterized. The effect of addition of MoO₃ (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 NaHSO₃ cocatalyst. The proposed polymerization mechanism indicated participation of radicals, primarily generated on a TiO₂ surface, with V⁵⁺/V⁴⁺ and/or Mo⁶⁺/Mo⁵⁺ 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 MoO₃ addition.

Keywords:

• MoO₃–modified V₂O₅/TiO₂
• redox-initiated polymerization
• methyl methacrylate
• V₂O₅/TiO₂

Notes

^a I: isotacticity, H: heterotacticity and S: syndiotacticity (ratios in %).