Effect ofN‐Methyl Imidazole and Dimethyl Pyrazole Ligands on Polymerization of di(2,4,6‐Trichlorophenolato)Cu(II)/Co(II) Complexes in Solid State

Abstract

Polymerization of 2,4,6-trichlorophenol (TCPH) was achieved through the thermal decomposition of the copper and cobalt complexes of TCPH with N-containing ligands [N-methyl imidazole (NMIz) and 3,5-dimethyl pyrazole (DMPz)]. The structural analysis of the complexes was performed by using Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), mass (MS), UV-VIS, diffuse reflectance (DRS) and electron spin resonance (ESR) spectroscopies, magnetic susceptibility balance and elemental analyses. Polymerization was achieved either in solid state or in melt, and the polymers were characterized by FTIR, nuclear magnetic resonance (NMR) spectroscopy, DSC, and viscosity measurements. The effects of the temperature and time dependencies of %Conversion on polymer synthesis were investigated. The cobalt complexes (having higher decomposition temperatures) were more stable than copper complexes (decomposing at lower temperatures). Thermal stability with respect to N-ligand shows that the complexes with NMIz are more stable than DMPz complexes of the same metal. The highest molecular weights (M w ) were achieved at the end of 3 hr of polymerization for C1 at 1708C, C2 at 1208C, and C4 at 1508C. The longer time at lowest conversion leads to highest M w of C1 at 1258C at the end of 24 hr, C2 at 908C at the end of 72 hr and at 1008C at the end of 48 hr.The M w of the polymeric products range between 8.5 Â 10 3 and 6.5 Â 10 4 . All polymers are rigid and have branched structures.

Poly(dibromophenylene oxide)s Through Atom Transfer Radical Rearrangement Polymerization of Various Transition Metal Complexes

“…Co(TBP) 2 (NMIZ) 2 complexes (Figure 2(b)) showed a sharp exothermic peak at 132.5 • C and an endothermic peak at 184.53 • C ,whereas Ni(TBP) 2 (NMIZ) 2 (Figure 2(c)) showed a single sharp exothermic peak at 143.93 • C. The exothermic peaks are attributed to the new bond formation during polymerization. This vision was previously supported by DSC-IR study (16) which showed the polymer formation at the peak temperature and the increase in the % conversions during polymerization beyond the exothermic peak temperatures. In order to investigate the origin complexes revealed endotherms that were close to the values reflected in thermograms of the original complexes ( Figure 2).…”

“…Up to date polymerization of halogenated phenols has been studied with transition and inner transition metal complexes with various amine ligands through various decomposition techniques which are electroinitiation in solution (13), thermal decomposition in solid state (14) and in solution (15 (16). Thus, authors considered the use of N-methylimidazole ligand as a powerful approach to archive better percent conversions.…”