TY - JOUR
T1 - Iron cluster and microstructure formation in metal-centered star block copolymers
T2 - Amphiphilic iron tris(bipyridine)-centered polyoxazolines
AU - Park, Cheolmin
AU - McAlvin, John E.
AU - Fraser, Cassandra L.
AU - Thomas, Edwin L.
PY - 2002
Y1 - 2002
N2 - The microstructure of a metal-centered six-arm star block copolymer, amphiphilic iron tris(bipyridine)-centered poly(2-ethyl-2-oxazoline)-b-poly(2-undecyl-2-oxazoline), [Fe{bpy-(PEOX-PUOX)2}3]2+, was investigated with small-angle X-ray scattering (SAXS), wide-angle X-ray scattering (WAXS), transmission electron microscopy (TEM), and atomic force microscopy (AFM). Cylindrical PEOX microdomains were observed in a matrix of PUOX. A similar cylindrical morphology was noted for bpy(PEOX-PUOX)2, the metal-free macroligand subunit of which the Fe star is comprised. Thin films simple-cast from chloroform solution onto carbon substrates annealed at 160 °C for ≈ 2 days revealed in both TEM and AFM the formation of nanoscale iron clusters (≈20-40-nm diameter) distributed randomly across the surface of the film. No clusters were evident in "as-cast" films subjected to TEM analysis without the annealing step, suggesting the importance of thermal treatment for nanocrystal formation. For bulk films, larger micrometer-scale (1-2μm) iron aggregates formed and segregated to the surface of the film after thermal treatment for ≈1 week. A liquid crystal-like mesophase due to undecyl alkyl side chain ordering was evidenced by SAXS and WAXS in the bulk sample.
AB - The microstructure of a metal-centered six-arm star block copolymer, amphiphilic iron tris(bipyridine)-centered poly(2-ethyl-2-oxazoline)-b-poly(2-undecyl-2-oxazoline), [Fe{bpy-(PEOX-PUOX)2}3]2+, was investigated with small-angle X-ray scattering (SAXS), wide-angle X-ray scattering (WAXS), transmission electron microscopy (TEM), and atomic force microscopy (AFM). Cylindrical PEOX microdomains were observed in a matrix of PUOX. A similar cylindrical morphology was noted for bpy(PEOX-PUOX)2, the metal-free macroligand subunit of which the Fe star is comprised. Thin films simple-cast from chloroform solution onto carbon substrates annealed at 160 °C for ≈ 2 days revealed in both TEM and AFM the formation of nanoscale iron clusters (≈20-40-nm diameter) distributed randomly across the surface of the film. No clusters were evident in "as-cast" films subjected to TEM analysis without the annealing step, suggesting the importance of thermal treatment for nanocrystal formation. For bulk films, larger micrometer-scale (1-2μm) iron aggregates formed and segregated to the surface of the film after thermal treatment for ≈1 week. A liquid crystal-like mesophase due to undecyl alkyl side chain ordering was evidenced by SAXS and WAXS in the bulk sample.
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U2 - 10.1021/cm010731d
DO - 10.1021/cm010731d
M3 - Article
AN - SCOPUS:0036205195
SN - 0897-4756
VL - 14
SP - 1225
EP - 1230
JO - Chemistry of Materials
JF - Chemistry of Materials
IS - 3
ER -