New Thermal Radical Inhibitors Based on a Triazene Metal Complex for Radical Polymerization.

New triazene based metal complexes such as Cu[1-(phenyldiazenyl)piperidine]2Br₂ (BTACHCuBr₂), Cu[1-(phenyldiazenyl)piperidine]2Cl₂ (BTACH-CuCl₂), Ni[1-(phenyldiazenyl)piperidine]2Cl₂ (BTACH-NiCl₂ · 6H₂O), Cu[2,2,6,6-tetramethyl-1-(phenyldiazenyl)piperidine]2Cl₂ (BTACM-SnCl₂), Ti[2,2,6,6-tetramethyl-1-(phenyldiazenyl)piperidine]2Cl₂ (BTACM-TiCl₂) were synthesized. All of the five compounds did not absorb in the visible light wavelength region and it does not have the color change disadvantage when using as an additive in polymerization. All materials also had thermal stability up to 245 °C. Among the synthesized compounds, BTACH-CuBr₂ showed the best radical inhibitor property when n-hexyl acrylate monomer was polymerized with the synthesized metal complexes at 150 °C isothermal condition. It exhibited more than 5 times of the polymerization delayed initiation compared to other synthesized metal complexes cases.