Ferrous sulfate heptahydrate

The reagents used were 2,2-diphenyl-1-picrylhydrazil (DPPH^•), 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox), 2,4,6-tris(2-pyridyl)-s-triazine (TPTZ), 2,20-azobis(2-amidinopropane) dihydrochloride (AAPH), fluorescein sodium salt and Folin & Ciocalteu^’s phenol reagent, all purchased from Sigma-Aldrich. Ferrous sulfate heptahydrate and gallic acid were purchased from Vetec, and sodium carbonate from J.T Baker were also used. All solvents and chemicals were of analytical grade.

All reagents were analytical grade (PA) and used without prior purification. Methyl methacrylate (MMA) 99%, vinyl pivalate (VPi) 99%, hexadecane 99%, benzoyl peroxide 75% and ethylene glycol dimethylacrylate (EGDMA) 98% were purchased from Sigma-Aldrich Brasil Ltda. (Rio de Janeiro, Brazil). Hydrochloric acid (HCl) 36.5–38% and oleic acid 99% were purchased from Synth (São Paulo, Brazil). Ferric chloride hexahydrate (FeCl₃·6H₂O) 97%, ferrous sulfate heptahydrate (FeSO₄·7H₂O) 99%, sodium hydroxide (NaOH) 99% and potassium persulfate (KPS) 99% were purchased from Vetec Química Fina Ltda. (Rio de Janeiro, Brazil) and 90% pure sodium dodecyl sulfate (SDS) was supplied by Reagen Produtos para Laboratórios Ltda. (Parana, Brazil). Nitrogen gas was supplied by White Martins Gases Industriais Ltda. (Rio de Janeiro, Brazil) with 99.5% purity. Scheme 1 illustrates the experimental protocol for the synthesis of poly(Methyl methacrylate)/Fe₃O₄/poly(vinyl pivalate) magnetic core–shell nanoparticles.