Magnetic composite nanoparticles consisting of helical poly(n-hexyl isocyanate) and Fe3O4 prepared via click reaction

A novel type of magnetic composite particles was constructed using helical poly(n-hexyl isocyanate) and Fe3O4. For this purpose, well-defined 4-ethynylbenzyloxy-terminal poly(n-hexyl isocyanate)s (PHIC-C equivalent to Cs) were synthesized via coordination polymerization by using an organotitanium catalyst. The PHIC-C equivalent to Cs were characterized by GPC, FT-IR and H-1 NMR techniques. UV-vis absorption spectra demonstrated that the PHIC-C equivalent to Cs adopted dynamic helical structures in tetrahydrofuran. Azide-modified magnetic Fe3O4 nanoparticles (Fe3O4@N-3 NPs) were prepared through the reaction between 3-azidopropyltrimethoxysilane and oleic acid-coated magnetic Fe3O4 NPs. The obtained clickable PHIC-C equivalent to C and Fe3O4@N-3 NPs were subjected to the Cu-catalyzed azide/alkyne cycloaddition for synthesizing the anticipated Fe3O4@PHIC composite NPs. FT-IR, TGA and TEM techniques confirmed the formation of the magnetic composite nanoparticles. UV-vis absorption spectra demonstrated that the PHIC chains coated on the magnetic Fe3O4 NPs adopted dynamic helical structures. XRD measurements revealed that coating PHIC chains on Fe3O4 nanoparticles did not change the phase properties of Fe3O4 nanoparticles. The Fe3O4@PHIC composite NPs showed a saturation magnetization of 17.8 emu g(-1) and the expected rapid magnetic responsivity.