Preparation and evaluation of a poly(N-vinylcarbazole)–Fe 3O 4 (PNVC–Fe 3O 4) nanocomposite

Abstract

N-vinylcarbazole (NVC) was polymerised in bulk in presence of nano sized Fe 3O 4 and a nanocomposite of poly (N-vinylcarbazole)–Fe 3O 4 (PNVC–Fe 3O 4) was isolated from the system. The yield of the PNVC–Fe 3O 4 composite increased with increasing time of polymerization as well as with [Fe 3O 4]/[PNVC] loadings. A charge transfer initiation of NVC polymerization was proposed which was followed by cationic propagation and monomer termination. The formation of PNVC was confirmed by FTIR, UV–vis, emission and 1H 1 NMR spectroscopic analyses. TGA and DTA analyses revealed a much higher thermogravimetric stability for the PNVC–Fe 3O 4 composite in contrast to PNVC. HRTEM studies revealed that the PNVC–Fe 3O 4 nanoparticles have an average grain size of 32 nm and that the Fe 3O 4 nanoparticles are fairly well-dispersed in the composite matrix. SEM analysis showed the presence of agglomerates of nano particles embedded in the matrix. XRD patterns for PNVC, PNVC–Fe 3O 4 composite and Fe 3O 4 particles were analyzed by constructing a Williamson–Hall plot from which particle size for the composite was estimated to be 34 nm in good agreement with the HRTEM value. The saturation magnetization value of the pure nano sized Fe 3O 4 was 6.98 J kg −1 T −1 at 300 K while those for the composites were 3.08 and 2.21 J kg −1 T −1 at 300 K for two different [Fe 3O 4]/[PNVC] loadings. σ ac-frequency variation was constant for PNVC but showed an increasing trend with higher Fe 3O 4:PNVC weight ratios in the composite.