Maghemite Nanoparticles on Supported Diblock Copolymer Nanostructures

Kashem, Mottakin M. Abul; Perlich, Jan; Schulz, Leander; Roth, Stephan V.; Petry, W.; Müller‐Buschbaum, Peter

doi:10.1021/ma070782h

Cited by 28 publications

(36 citation statements)

References 68 publications

(143 reference statements)

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“…Although nanoparticles are well-known to prevent dewetting, [38][39][40][41][42][43][44][45][46] in the ultrathin film case nanoparticles retard dewetting. 9 Recently, a similar kind of structure was reported in the case of an ultrathin film using similar materials. 9 In addition, the structures show no sign of fracture introduced features due to the lift-off of the cover plate.…”

Section: Resultsmentioning

confidence: 63%

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Correlated Roughness in Polymer Films Containing Maghemite Nanoparticles

et al. 2008

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Two different uniform thicknesses (8 and 68 nm) of a nanocomposite film comprising diblock copolymer matrix and magnetic nanoparticles filler have been installed in one sample preparation step under identical condition simultaneously. Long-range interface correlations are investigated. Maghemite (F 2 O 3 ) nanoparticles covered with polystyrene chains are incorporated in polystyrene-block-polyisoprene to produce such film. The film is investigated with atomic force microscopy (AFM), X-ray reflectivity (XR), and scanning microfocus grazing incident small-angle X-ray scattering (GISAXS). The roughness of the substrate is replicated on the 68 nm thick composite film surface resulting in roughness correlation in a waveguide manner. No roughness correlation is observed in 8 nm film.

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Section: Resultsmentioning

confidence: 63%

“…9 Recently, a similar kind of structure was reported in the case of an ultrathin film using similar materials. 9 In addition, the structures show no sign of fracture introduced features due to the lift-off of the cover plate.…”

Section: Resultsmentioning

confidence: 63%

Correlated Roughness in Polymer Films Containing Maghemite Nanoparticles

et al. 2008

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“…1 Frequently, diblock copolymer templates have been used to guide specially coated MNPs in the polymer matrix to get good control on the MNP dispersion. [12][13][14][15][16][17][18][19] Recently, the combination of copolymers with hydrophobic and hydrophilic parts and MNPs gained interest due to the improved formulation possibilities, as properly coated nanoparticles can be guided to the corresponding segments of the copolymer. 20 In the present work, we present a nanocomposite hydrogel based on hydrophobically modified ethoxylated urethane (HEUR) polymers with embedded core-shell magnetite (Fe 3 O 4 ) nanoparticles (Fig.…”

Section: Introductionmentioning

confidence: 99%

Multi-stage freezing of HEUR polymer networks with magnetite nanoparticles

Campanella¹,

Holderer²,

Raftopoulos

et al. 2016

Soft Matter

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We observe a change in the segmental dynamics of hydrogels based on hydrophobically modified ethoxylated urethanes (HEUR) when hydrophobic magnetite nanoparticles (MNPs) are embedded in the hydrogels. The dynamics of the nanocomposite hydrogels is investigated using dielectric relaxation spectroscopy (DRS) and neutron spin echo (NSE) spectroscopy. The magnetic nanoparticles within the hydrophobic domains of the HEUR polymer network increase the size of these domains and their distance. The size increase leads to a dilution of the polymers close to the hydrophobic domain, allowing higher mobility of the smallest polymer blobs close to the "center". This is reflected in the decrease of the activation energy of the β-process detected in the DRS data. The increase in distance leads to an increase of the size of the largest hydrophilic polymer blobs. Therefore, the segmental dynamics of the largest blobs is slowed down. At short time scales, i.e. 10(-9) s < τ < 10(-3) s, the suppression of the segmental dynamics is reflected in the α-relaxation processes detected in the DRS data and in the decrease of the relaxation rate Γ of the segmental motion in the NSE data with increasing concentration of magnetic nanoparticles. The stepwise (multi-stage) freezing of the small blobs is only visible for the pure hydrogel at low temperatures. On the other hand, the glass transition temperature (Tg) decreases upon increasing the MNP loading, indicating an acceleration of the segmental dynamics at long time scales (τ∼ 100 s). Therefore, it would be possible to tune the Tg of the hydrogels by varying the MNP concentration. The contribution of the static inhomogeneities to the total scattering function Sst(q) is extracted from the NSE data, revealing a more ordered gel structure than the one giving rise to the total scattering function S(q), with a relaxed correlation length ξNSE = (43 ± 5) Å which is larger than the fluctuating correlation length from a static investigation ξSANS = (17.2 ± 0.3) Å.

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“…[13][14][15] Nanostructures are formed by phase separation in the case of polymer blends, by micro-phase separation for block copolymers or by dewetting of thin polymer films. [16,17] Thus, the nanostructure can be controlled via surface treatments of the substrate such as cleaning procedures, via the chemical compositions of the used polymers and postpreparation treatments like temperature and solvent annealing steps. [18][19] Besides using nanostructured surfaces as modified surfaces, they can be used as templates for deposition processes or as interfaces in multilayer systems.…”

Section: Introductionmentioning

confidence: 99%

Photoactive Nanostructures of Polypyrrole

Ruderer¹,

Hirzinger²,

Müller‐Buschbaum³

2009

ChemPhysChem

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The creation of nanostructures of the photoactive polymer polypyrrole (PPy) on glass substrates with the spin-coating method is described. No additional post-production treatment is necessary to obtain uniformly distributed photoactive nanostructures on macroscopically scaled substrates. Based on X-ray reflectivity measurements, the critical solution concentration of PPy below which these nanostructures develop is determined. The PPy nanostructures are displayed with atomic force microscopy (AFM) measurements, which prove that the nanostructures form directly on the substrate. With UV/Vis spectroscopy the absorption behavior of the nanostructures is probed in comparison to PPy films and PPy solutions. A linear dependence of the absorption of the nanostructure on the surface coverage measured with AFM is detected. The influence of confinement on the conjugation length results in a modified absorption behavior of the nanostructures.

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Maghemite Nanoparticles on Supported Diblock Copolymer Nanostructures

Cited by 28 publications

References 68 publications

Correlated Roughness in Polymer Films Containing Maghemite Nanoparticles

Correlated Roughness in Polymer Films Containing Maghemite Nanoparticles

Multi-stage freezing of HEUR polymer networks with magnetite nanoparticles

Photoactive Nanostructures of Polypyrrole

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