Preparation and characterization of polystyrene grafted magnesium hydroxide nanoparticles via surface-initiated atom transfer radical polymerization

Polystyrene grafted magnesium hydroxide nanoparticles [PS–Mg(OH)₂] were prepared by the followed two steps: first magnesium hydroxide nanoneedles modified by α-bromoisobutyric acid [BA–Mg(OH)₂] were synthesized through injecting alkaline into magnesium chloride solution; then polystyrene grafted magnesium hydroxide particles [PS–Mg(OH)₂] were successfully prepared by the surface-initiated atom transfer radical polymerization (SI-ATRP) of styrene from the macroinitiators, BA–Mg(OH)₂, in toluene system with the catalysts of 2,2′-bipyridine and Cu(I)Br. The obtained PS–Fe₃O₄ nanoparticles were characterized by Fourier transform infrared spectroscopy (FT-IR), elemental analysis (EA), transmission electron microscope (TEM), sedimentation test, and viscosity test. The FT-IR analyses showed that the polystyrene had been covalently grafted onto the surfaces of the nanoneedles [BA–Mg(OH)₂]. The graft polymerizations exhibited the characteristics of the controlled/“living” polymerization. TEM showed that grafted polymer chains on nanoparticles could prevent the aggregation of PS–Mg(OH)₂ nanoparticles markedly in toluene and improve their compatibility with organic phase. The graft parameters could be calculated from the elemental analysis (EA) results, and linear plots of percentage of grafting (PG %) and conversion of monomer (C %) versus polymerizing time were achieved, respectively. Narrow molecular weight distribution (M _w/M _n) for the graft polymer samples were characterized by the gel permeation chromatography (GPC).