Surface-initiated atom transfer radical polymerization of poly(4-vinylpyridine) from magnetite nanoparticle

Abstract

Surface modification of magnetite nanoparticles (MNP) with a covalently bonded poly(4-vinylpyridine) (P4VP) by surface-initiated atom transfer radical polymerization (ATRP) is reported in this article. MNP was first prepared via thermal decomposition of Fe(acac)3 and grafted with an ATRP initiator on its surface. ATRP of 4-vinylpyridine was then initiated from the MNP surface in the presence of CuBr/PMDETA (1,1,4,7,7-pentamethyldiethylenetriamine) catalytic complex in dioxane. FTIR in combination with photocorrelation spectroscopy (PCS), thermogravimetric analysis (TGA), and vibrating sample magnetometry (VSM) techniques indicated the growth of P4VP on the particle surface with increasing ATRP reaction time. Transmission electron microscopy (TEM) disclosed that the average particle size was 8 nm in diameter with some nanoaggregation observed. The PCS results revealed that decreasing the solution pH enhanced the particle dispersibility because of the positive charge repulsion of the protonated P4VP on the particle surface. TGA was also performed to elucidate the composition of P4VP shell and magnetite core in the hybrid material.