Iron cluster and microstructure formation in metal-centered star block copolymers

Amphiphilic iron tris(bipyridine)-centered polyoxazolines

Cheolmin Park, John E. McAlvin, Cassandra L. Fraser, Edwin L. Thomas

Research output: Contribution to journalArticle

52 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)1225-1230
Number of pages6
JournalChemistry of Materials
Volume14
Issue number3
DOIs
Publication statusPublished - 2002 Apr 9

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X ray scattering
Block copolymers
Stars
Iron
Metals
Microstructure
Transmission electron microscopy
Atomic force microscopy
Heat treatment
Liquid Crystals
Chloroform
Chlorine compounds
Liquid crystals
Nanocrystals
Carbon
Annealing
Thin films
Substrates

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

Cite this

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abstract = "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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Iron cluster and microstructure formation in metal-centered star block copolymers : Amphiphilic iron tris(bipyridine)-centered polyoxazolines. / Park, Cheolmin; McAlvin, John E.; Fraser, Cassandra L.; Thomas, Edwin L.

In: Chemistry of Materials, Vol. 14, No. 3, 09.04.2002, p. 1225-1230.

Research output: Contribution to journalArticle

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T2 - Amphiphilic iron tris(bipyridine)-centered polyoxazolines

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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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