Well‐defined cylindrical polymer brushes with poly(acrylic acid) (PAA) cores and poly(n‐butyl acrylate) (PnBA) shells have been synthesized via a combination of anionic polymerization and atom transfer radical polymerization. These amphiphilic brushes are unimolecular cylindrical micelles and can be used as single‐molecular templates for the synthesis of inorganic nanoparticles, because the carboxylic acid groups (or carboxylate groups, after neutralization) in the polymer core can coordinate with various metal ions such as Fe3+ and Fe2+. Ultrafine magnetic nanoparticles were successfully synthesized within the core of these polymer brushes, as confirmed by various characterization techniques. Mössbauer spectroscopy and magnetization measurements indicate that the hybrid nanocylinders exhibit interesting superparamagnetic behavior.
The Raman spectrum of a cylindrical core-shell polymer brush containing Fe 3+ ions was measured in a confocal spectrometer equipped with an He-Ne laser. During irradiation, the polymer matrix decomposed, and carbonaceous compounds containing sp 2 and sp 3 hybridized carbon were formed. Simultaneously, the strong and narrow Raman lines of crystalline a-Fe 2 O 3 (hematite) began to show up in the spectrum. After prolonged irradiation, the carbon signals decreased, whereas the hematite peaks remained strong. Similar experiments with the same polymer containing Cu 2+ ions resulted only in very weak formation of cupric oxide.
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