Electrical, thermal behaviors and synthesis of intramolecular cobalt phthalocyanine with single-chain polymer structure

Abstract

Firstly, poly[4-(4-vinylbenzyl)oxy)phthalonitrile]-co-styrene, [poly(VBOP-co-St], which is used as a linear copolymer precursor containing phthalonitrile pendant group was prepared from copolymerization of VBOP and St by atom transfer radical polymerization method at 110 °C. Then, complex synthesis of cobalt phthalocyanine in the single-chain polymer (SCP-CoPc complex) via the intramolecular macrocyclization reaction of cobalt and phthalonitrile group in poly(VBOP-co-St) was carried out at 150 °C in the presence of excess cyclohexanol. Both linear copolymer precursor and formation of cobalt phthalocyanine within a single-chain polymer were confirmed by FT-IR, 1H-NMR, 13C-NMR and UV/Vis spectroscopy techniques. Particularly, the formation of SCP-CoPc complex was characterized by almost disappearance of –C≡N band at 2230 cm−1 of the FT-IR and appearance of Q band around 672 nm and the B band in the near UV region at 350 nm of UV/Vis spectroscopy. The pure poly(VBOP-co-St), SCP-CoPc complex and the residue SCP-CoPc complex heated to 500 °C were characterized by SEM images, and the element analyses were estimated from X-ray energy dispersive spectroscopy (X-ray EDS). The EDS elemental analysis results of the residual of SCP-CoPc complex degraded to 500 °C showed that CoO [cobalt(II)oxide] compound occurred. The thermal properties of poly(VBOP-co-St) and SCP-CoPc complex were investigated through thermogravimetric analysis and differential scanning calorimeter. The conducting nanographene-based SCP-CoPc composites were prepared. DC and AC electrical conductivity and dielectric properties were investigated. The ac dielectric measurements of poly(VBOP-co-St), SCP-CoPc complex and composites were investigated at room temperature between 100 and 20 kHz depending on the alternating current conductivities. Also, the activation energy profile of SCP-CoPc/4% (by wt) nanographene composite was revealed by measuring the DC conductivity of individual composite material.