In situ synthesis of the Fe₃O₄@poly(4-vinylpyridine)-block-polystyrene magnetic polymer nanocomposites via dispersion RAFT polymerization

Figures & data

Scheme 1. Schematic illustration for the preparation of Fe₃O₄@nanoparticles.

Table 1. Characteristics of the P4VP-TTC and P4VP-b-PS block copolymer.

Polymer^a	Mtheo.(g mol^-1)	Mn^d (g mol^-1)	PDI^d
P4VP21-trithiocarbonate(P4VP21-TTC)	2573^b	2200	1.32
P4VP21-b-PS156	18820^c	12300	1.26

^a The subscript number denotes the degree of polymerization.

^b Determined by comparison of the intensity of the resonance of methyl group signals at δ 0.95 from the RAFT to the intensity of the resonance from δ 8.1 to 8.6 of pyridyl group proton from P4VP for P4VP-TTC sample.

^c Determined by comparison of the intensity of the signals at δ 8.1 to 8.6 of the pyridyl group proton from P4VP block and δ 6.2 to 7.28 of the phenyl ring from PS block of the P4VP-b-PS polymer in the ¹H NMR spectra.

^d Molecular weight and polydispersity (PDI) of polymers were determined by GPC. The GPC system was calibrated with poly(methyl methacrylate) PMMA standards.

Scheme 2. Schematic illustration of the synthesis of Fe³⁺@P4VP-b-PS nanoparticles.

Figure 1. TEM images of samples prepared from (A) P4VP-b-PS nanoparticles;(B) Fe³⁺@ P4VP-b-PS nanoparticles and (C) Enlargement of the picture in the box (Note: The molar ratio of Fe³⁺ with respect of pyridyl groups of P4VP is 1:10).

Figure 2. TGA of (A) P4VP-b-PS nanoparticles and (B) Fe³⁺@P4VP-b-PS nanoparticles (Note: The molar ratio of Fe³⁺ with respect of pyridyl groups of P4VP is 1:10).

Figure 3. XPS spectra of (A) recorded for P4VP-b-PS nanoparticle and Fe₃O₄@P4VP-b-PS nanoparticle; (B) Fe2p signals for Fe₃O₄@P4VP-b-PS and (C) XRD patterns of neat PS-b-P4VP and Fe₃O₄@P4VP-b-PS nanoparticle. (Note: The molar ratio of Fe³⁺ with respect of pyridyl groups of P4VP is 1:10; The molar ratio of Fe³⁺:Fe²⁺is 1:1).

Figure 4. FT-IR spectra for P4VP-b-PS and Fe₃O₄@P4VP-b-PS nanoparticles.

Figure 5. TEM images of P4VP-b-PS nanoparticles (A) and Fe₃O₄@P4VP-b-PS nanoparticles prepared through dispersion polymerization. The molar ratio of FeCl₃:P4VP is 1:10 in (B), 1:5 in (C), 1:2 in (D). (E) the enlarged TEM picture of (D). (Note: the molar ratio of Fe³⁺:Fe²⁺is 1:1 in all samples.).

Figure 6. STEM-HAADF images of (A) Fe₃O₄@P4VP-b-PS Nanoparticles prepared through dispersion polymerization. The molar ratio of FeCl₃:P4VP is 1:2. (Note: the molar ratio of Fe³⁺:Fe²⁺ is 1:1); (B)-(D) EDX elemental mapping images of (B) C map, (C) Fe map and (D) N map.

Figure 7. Magnetic hysteresis curves (A) of Fe₃O₄@P4VP-b-PS nanoparticles prepared through dispersion polymerization. The molar ratio of FeCl₃:P4VP is 1:10 in (a), 1:5 in (b), 1:2 in (c). (Note: the molar ratio of Fe³⁺:Fe²⁺ is 1:1 in all samples.) (B) A magnified view of the magnetization curves at low applied fields. (C) TGA of Fe₃O₄@P4VP-b-PS nanoparticles with molar ratio of FeCl₃:P4VP 1:10 in (a), 1:5 in (b), 1:2 in (c). (D) Photograph of the ferrofluid placed next to a magnet.