Magnetic properties and morphology of block copolymer-cobalt oxide nanocomposites

Ahmed, Sufi R.; Kofinas, Peter

doi:10.1016/j.jmmm.2004.09.009

Cited by 56 publications

(19 citation statements)

References 10 publications

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“…3a), the broad absorption bands at approximately 3434, 1638 and 1130 cm -1 are attributed to the stretching and bending vibrations of the water molecules absorbed by the samples or KBr [31,32]. The strong bands at 667 cm -1 are attributed to the stretching vibration mode of Co-O in which Co is Co 2?…”

Section: Ft-ir Spectra Of Metal Oxidesmentioning

confidence: 99%

Synthesis of Co(II) and Cr(III) salicylidenic Schiff base complexes derived from thiourea as precursors for nano-sized Co3O4 and Cr2O3 and their catalytic, antibacterial properties

Kafi‐Ahmadi

Shirmohammadzadeh

2017

J Nanostruct Chem

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This study focuses on the synthesis of Co(II) and Cr(III) Schiff base complexes obtained from thiourea. The complexes were synthesized by template method and characterized by elemental analysis (CHNS), FT-IR, UVvis spectroscopy, conductivity measurement and magnetic moment. The spectroscopic studies suggested the octahedral and square-pyramidal structures for Co(II) and Cr(III) complexes, respectively. Then the complexes were used as precursors for preparation of Co 3 O 4 and Cr 2 O 3 nanoparticles via solid-state thermal decomposition without using a catalyst, toxic solvent, template or surfactant and complicated equipment, which makes it efficient, one-step, simple and environment-friendly. The chemical structure of the metal oxides is studied by FT-IR, XRD and SEM. To investigate the applications of the synthesized complexes, in the next step, the complexes were screened for antibacterial activity against clinically important bacteria such as Escherichia coli, Staphylococcus aureus, and Bacillus subtilis. The Cr(III) and Co(II) complexes showed good biological activity against all the tested bacteria. Also, the catalytic activities of the complexes were studied in toluene using non-toxic hydrogen peroxide as the oxidant. The results showed that Co(II) complex has catalytic activity for oxidation of toluene, but Cr(III) complex did not show any catalytic activity.

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Section: Ft-ir Spectra Of Metal Oxidesmentioning

confidence: 99%

Synthesis of Co(II) and Cr(III) salicylidenic Schiff base complexes derived from thiourea as precursors for nano-sized Co3O4 and Cr2O3 and their catalytic, antibacterial properties

Kafi‐Ahmadi

Shirmohammadzadeh

2017

J Nanostruct Chem

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“…Incorporation of these NPs into polymer matrices results in polymer nanocomposites (PNC), which combine the functionality of the NPs with the processability of the matrix [7][8][9][10][11][12][13]. Typically, the dispersion of NPs in polymer matrices is problematic and the NPs tend to macrophase separate or aggregate in the host matrix [14].…”

Section: Introductionmentioning

confidence: 99%

Dispersion of polymer-grafted magnetic nanoparticles in homopolymers and block copolymers

Ohno

Ladmiral

et al. 2008

Polymer

155

145

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The dispersion of magnetic nanoparticles (NPs) in homopolymer poly(methyl methacrylate) (PMMA) and block copolymer poly(styrene-b-methyl methacrylate) (PS-b-PMMA) films is investigated by TEM and AFM. The magnetite (Fe 3 O 4 ) NPs are grafted with PMMA brushes with molecular weights from M = 2.7 to 35.7 kg/mol. Whereas a uniform dispersion of NPs with the longest brush is obtained in a PMMA matrix (P = 37 and 77 kg/mol), NPs with shorter brushes are found to aggregate. This behavior is attributed to wet and dry brush theory, respectively. Upon mixing NPs with the shortest brush in PS-b-PMMA, as-cast and annealed films show a uniform dispersion at 1 wt%. However, at 10 wt%, PS-b-PMMA remains disordered upon annealing and the NPs aggregate into 22 nm domains, which is greater than the domain size of the PMMA lamellae, 18 nm. For the longest brush length, the NPs aggregate into domains that are much larger than the lamellae and are encapsulated by PS-b-PMMA which form an onion-ring morphology. Using a multicomponent Flory-Huggins theory, the concentrations at which the NPs are expected to phase separate in solution are calculated and found to be in good agreement with experimental observations of aggregation. The dispersion of magnetic nanoparticles (NPs) in homopolymer poly(methyl methacrylate) (PMMA) and block copolymer poly(styrene-b-methyl methacrylate) (PS-b-PMMA) films is investigated by TEM and AFM. The magnetite (Fe 3 O 4 ) NPs are grafted with PMMA brushes with molecular weights from M ¼ 2.7 to 35.7 kg/mol. Whereas a uniform dispersion of NPs with the longest brush is obtained in a PMMA matrix (P ¼ 37 and 77 kg/mol), NPs with shorter brushes are found to aggregate. This behavior is attributed to wet and dry brush theory, respectively. Upon mixing NPs with the shortest brush in PS-b-PMMA, as-cast and annealed films show a uniform dispersion at 1 wt%. However, at 10 wt%, PS-b-PMMA remains disordered upon annealing and the NPs aggregate into 22 nm domains, which is greater than the domain size of the PMMA lamellae, 18 nm. For the longest brush length, the NPs aggregate into domains that are much larger than the lamellae and are encapsulated by PS-b-PMMA which form an onion-ring morphology. Using a multi-component Flory-Huggins theory, the concentrations at which the NPs are expected to phase separate in solution are calculated and found to be in good agreement with experimental observations of aggregation.

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“…Upon removing the minor component, Co was electrochemically deposited, resulting in small metal cylinders 14 nm in diameter with lengths of 500 nm and a coercivity (H c ) of 800 Oe (Orsteds) 15 . A second approach selectively deposits the precursor of a magnetic material into one domain of the BCP followed by a reduction reaction to produce the magnetic material [21][22][23][24] . Using this strategy, Co nanoparticles were reported 21 with dimensions ranging from 10 to 288 nm and H c values between 20 and 360 Oe.…”

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confidence: 99%

Room temperature magnetic materials from nanostructured diblock copolymers

et al. 2011

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nanostructured magnetic materials are important for many advanced applications. Consequently, new methods for their fabrication are critical. However, coupling self-assembly to the generation of magnetic materials in a simple, straight-forward manner has remained elusive. Although several approaches have been considered, most have multiple processing steps, thus diminishing their use of self-assembly to influence magnetic properties. Here we develop novel block copolymers that are preprogrammed with the necessary chemical information to microphase separate and deliver room temperature ferromagnetic properties following a simple heat treatment. The importance of the nanostructured confinement is demonstrated by comparison with the parent homopolymer, which provides only paramagnetic materials, even though it is chemically identical and has a higher loading of the magnetic precursor. In addition to the room temperature ferromagnetic properties originating from the block copolymer, the in situ generation densely functionalizes the surface of the magnetic elements, rendering them oxidatively stable.

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Magnetic properties and morphology of block copolymer-cobalt oxide nanocomposites

Cited by 56 publications

References 10 publications

Synthesis of Co(II) and Cr(III) salicylidenic Schiff base complexes derived from thiourea as precursors for nano-sized Co3O4 and Cr2O3 and their catalytic, antibacterial properties

Synthesis of Co(II) and Cr(III) salicylidenic Schiff base complexes derived from thiourea as precursors for nano-sized Co3O4 and Cr2O3 and their catalytic, antibacterial properties

Dispersion of polymer-grafted magnetic nanoparticles in homopolymers and block copolymers

Room temperature magnetic materials from nanostructured diblock copolymers

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