References of "Stamm, Manfred"
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See detailUltrathin transparent conductive films of polymer-modified multiwalled carbon nanotubes
Bocharova, Vera; Kiriy, Anton; Oertel, Ulrich et al

in Journal of Physical Chemistry B (2006), 110(30), 14640-14644

Deposition of multiwalled carbon nanotubes modified by poly(2-vinylpyridine) (CNT-g-P2VP) from aqueous dispersions at low pH is an effective method to prepare homogeneous ultrathin films with a tunable ... [more ▼]

Deposition of multiwalled carbon nanotubes modified by poly(2-vinylpyridine) (CNT-g-P2VP) from aqueous dispersions at low pH is an effective method to prepare homogeneous ultrathin films with a tunable CNTs density. A percolation threshold of 0.25 mu g/cm(2) and a critical exponent alpha = 1.24 have been found from dc conductivity measurements. The sheet resistance value agrees with the percolation theory for 2D films. According to AFM and electrical measurements, even when only 5% of the surface is covered by CNT-g-P2VPs, the sheet resistance is of the order of 1 M Omega/sq, which indicates that conductivity is imparted by a network of an ultralow density. When the film transmittance decreases down to similar to 70% at 550 nm, the occupied surface area is similar to 15% and sheet resistance falls down to similar to 90 k Omega/sq. These data show that undesired in-plane clustering does not occur upon the dispersion casting of the films and that high-quality networks of CNT-g-P2VPs are built up. The electrosteric stabilization of the CNT-g-P2VP dispersions in water at low pH is at the origin of this desired behavior. Although the multiwalled CNT films prepared in this work are less conductive and less transparent than the SWNTs films, they could find applications, e. g., in touch screens, reflective displays, EMI shielding, and static charge dissipation. [less ▲]

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See detailSimple method for the stretching and alignment of single adsorbed synthetic polycations
Bocharova, Vera; Kiriy, Anton; Stamm, Manfred et al

in Small : Nano Micro (2006), 2(7), 910-916

Spin-coating of isolated positively charged macromolecules onto mica in the presence of octylamine was found to be a simple and general method of stretching and aligning the macromolecular chains. The ... [more ▼]

Spin-coating of isolated positively charged macromolecules onto mica in the presence of octylamine was found to be a simple and general method of stretching and aligning the macromolecular chains. The contour length and molar mass for the stretched macromolecules can be directly measured by atomic force microscopy, which makes this method a very useful analytical tool. Moreover, the molecular height is increased by codeposition with octylamine, which drastically improves the molecular resolution and allows even ultrathin polycations to be visualized. The reason for the key role of the octylamine is found in the formation of an ultrathin liquidlike alkylamine film, which reduces the surface energy of mica and weakens the interactions between the surface and the charged macromolecules. [less ▲]

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See detailMolecular weight determination by visualization of stretched polycation molecules
Bocharova, Vera; Kiriy, Anton; Stamm, Manfred et al

in PMSE Preprints (2006), 95

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See detailPolymer-modified multi-walled carbon nanotubes for ultrathin transparent conductive coatings
Bocharova, Vera; Kiriy, Anton; Ulrich, Oertel et al

in PMSE Preprints (2006), 95

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See detailSynthesis and deposition of water-dispersed prussian blue nanocrystals on polymers and CNTs
Boccharova, Vera; Gorodyska, Ganna; Kiriy, Anton et al

in Progress in Colloid & Polymer Science (2006), 132

Nanoparticles can be used for decoration and functionalization of single polymer molecules that have been adsorbed to a solid substrate. Initial attempts to prepare Prussian Blue nanoclusters by a layer ... [more ▼]

Nanoparticles can be used for decoration and functionalization of single polymer molecules that have been adsorbed to a solid substrate. Initial attempts to prepare Prussian Blue nanoclusters by a layer-by-layer deposition technique of hexacyanoferrate anions and ferric cations onto isolated polycation chains in water failed because of the desorption of the first layer upon deposition of the next one. A simple method for the preparation of charge-stabilized Prussian Blue nanoparticles of readily adjustable size is reported. Prussian Blue nanoparticles have been purified by addition of non-solvents and redispersed in water without aggregation. Thus formed Prussian Blue nanoparticles are crystalline and display a long-range ferromagnetic ordering at 5.1 K. Prussian Blue nanoparticles were selectively deposited along single polycation molecules to form a one-dimensional array or were attached to the surface of carbon nanotubes (CNTs) functionalized with poly2-vinylpyridine (P2VP). These nanoparticle-based nanostructures might be useful materials for manufacture of electrooptical devices, or mechanically robust ion-sieving membranes. [less ▲]

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See detailA novel strategy for the dispersion, selective deposition and decoration of carbon nanotubes
Detrembleur, Christophe ULg; Lou, Xudong; Stoffelbach, François et al

Poster (2005, May 11)

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See detailSurface modification of multiwalled carbon nanotubes by poly(2-vinylpyridine): Dispersion, selective deposition, and decoration of the nanotubes
Lou, Xudong; Detrembleur, Christophe ULg; Pagnoulle, Christophe et al

in Advanced Materials (2004), 16(23-24), 2123-2127

Polymer modification of carbon nanotubes is accomplished using a grafting-to approach. Radicals formed by the thermolysis of poly(2-vinylpyridine) terminated with a radical-stabilizing nitroxide can react ... [more ▼]

Polymer modification of carbon nanotubes is accomplished using a grafting-to approach. Radicals formed by the thermolysis of poly(2-vinylpyridine) terminated with a radical-stabilizing nitroxide can react with the surface of nanotubes, resulting in grafting densities up to 12 wt.-%. The modified nanotubes, which are easily dispersed in water, can immobilize metal nanoclusters on their surfaces. [less ▲]

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See detailThe influence of an acid-base-equilibrium on the adsorption behaviour of a weak polyampholyte
Mahltig, Boris; Jérôme, Robert ULg; Stamm, Manfred

in Journal of Polymer Research (2003), 10(4), 219-223

A weak diblock polyampholyte PMAA-b-PDMAEMA, poly(methacrylic acid)-block-poly((dimethylamino)ethyl methacrylate), was investigated as a model system for the influence of an acid-base-equilibrium of a ... [more ▼]

A weak diblock polyampholyte PMAA-b-PDMAEMA, poly(methacrylic acid)-block-poly((dimethylamino)ethyl methacrylate), was investigated as a model system for the influence of an acid-base-equilibrium of a phthalic acid buffer system on the polyelectrolyte adsorption behaviour. The adsorption of polyampholyte from aqueous solution onto silicon surfaces is known to be strongly influenced by the parameters of the polymer solution and the properties of the polyampholyte itself like block ratio or molecular weight. In the case of the investigated polyampholytes, the main parameter with the most significant influence on the adsorption is the pH. The big influence of pH on adsorption results from the charges of the polymer chains and the substrate, which are determined by the pH. Therefore, it should be useful to investigate the influence of a buffer system on the polyampholyte adsorption. On the one hand the buffer system enables to determine the pH of the aqueous polyampholyte solution more precisely. On the other hand the concentrations of different phthalic species like the phthalic acid, the hydrogen phthalate and the phthalate are strongly influenced by pH. These different species were observed to have a strong influence on the adsorption behaviour of the polyampholyte, so the adsorption as function of pH was observed to be also determined by the acid-base-equilibrium of the buffer system. The adsorbed amount of polyampholyte dried after the adsorption process was determined using ellipsometry, while the surface topography of these adsorbed layers were characterized by atomic force microscopy (AFM). [less ▲]

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See detailReversible chemical patterning on stimuli-responsive polymer film: Environment-responsive lithography
Ionov, Leonid; Minko, Sergiy; Stamm, Manfred et al

in Journal of the American Chemical Society (2003), 125(27), 8302-8306

We report on a novel type of chemical patterning based on thin stimuli-responsive polymer films. The basic concept is the permanent storage (writing) of a pattern, which is reversibly developed and erased ... [more ▼]

We report on a novel type of chemical patterning based on thin stimuli-responsive polymer films. The basic concept is the permanent storage (writing) of a pattern, which is reversibly developed and erased upon exposure to appropriate environment, e.g., solvent, pH, and temperature. The smart surface is fabricated from the mixed brush of poly(2-vinylpyridine) and polyisoprene. The mixed brush demonstrates switching behavior upon exposure to different solvents. Cross-linking of polyisoprene via illumination through a photomask results in formation of patterns with suppressed switching. Due to the contrast in switching between illuminated and dark areas, exposure of the smart surface to different solvents causes either reversible formation or erasing of chemical contrast between the illuminated and dark areas. Thus, the pattern surface can very locally attract colloidal particles or can be wetted by water only upon exposure to the special solvent which introduces the contrast between the illuminated and dark areas. Appearance of the patterns indicates particular environment and can be used for local switching of adsorption. [less ▲]

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See detailDesorption behaviour of regular adsorbed polyampholytic layers
Mahltig, Boris; Gohy, Jean-François; Jérôme, Robert ULg et al

in Journal of Polymer Research (2003), 10(2), 69-77

The desorption behaviour of the diblock polyampholyte PMAA-b-PDMAEMA, poly(methacrylic acid)-block-poly ((dimethylamino)ethyl methacrylate), preadsorbed on silicon substrates was investigated under the ... [more ▼]

The desorption behaviour of the diblock polyampholyte PMAA-b-PDMAEMA, poly(methacrylic acid)-block-poly ((dimethylamino)ethyl methacrylate), preadsorbed on silicon substrates was investigated under the influence of several desorption agents. The investigated polyampholyte is known to adsorb in regular structures directly from aqueous solutions onto silicon substrates. While the adsorption process is mainly determined by electrostatic interactions, two kinds of desorption mechanism should be assumed. The first mechanism is based on changed electrostatic conditions caused for instance by a strong change in pH of the aqueous solution. The other mechanism is observed after treatment with hydrophobic organic solvent, which leads to the desorption of hydrophobic adsorbed polyampholyte chains, while the electrostatically attached ones will not be influenced. To complete the desorption experiments with organic solvents also adsorption experiments from analogous polyampholytic solutions in the same organic solvents were performed. The amount of polymer at the substrate surface after adsorption or desorption experiments was determined using ellipsometry. Atomic force microscopy (AFM) was used to investigate the surface topography of dried samples after the desorption process. [less ▲]

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See detailAdsorption and structure formation of the weak polyelectrolytic diblock copolymer, PVP-b-PDMAEMA
Mahltig, Boris; Gohy, Jean-François; Antoun, Sayed et al

in Colloid and Polymer Science (2002), 280(6), 495-502

This paper reports on the pH-dependent adsorption of weak the polyelectrolytic diblock copolymer poly(2-vinylpyridine)-block-poly(dimethylaminoethyl methacrylate), (PVP-b-PDMAEMA). Aqueous PVP-b-PDMAEMA ... [more ▼]

This paper reports on the pH-dependent adsorption of weak the polyelectrolytic diblock copolymer poly(2-vinylpyridine)-block-poly(dimethylaminoethyl methacrylate), (PVP-b-PDMAEMA). Aqueous PVP-b-PDMAEMA solutions have been adsorbed on alkaline pretreated silicon substrates. Altogether two copolymers differing in block ratio and molecular weight were used for the investigations. While the electrical charge of both samples in solution was investigated by electrophoretic measurements, the adsorbed polymer layers were studied with ellipsometry and atomic force microscopy (AFM). Depending on pH the electrical charge of both blocks of the diblock copolymer varied. Three different regimes have been identified. Under acidic conditions at pH < 5, both blocks are mainly positively charged. At medium pH between 5 and 8, only the PDMAEMA block is positively charged. At pH > 8, both blocks are nearly uncharged and a polymer precipitation occurred in solution. Each of these pH regimes was characterized by a specific adsorption behaviour leading to two adsorption maxima at acidic and alkaline pH values, while at medium pH a plateau in the adsorbed amount was observed. Moreover, the structures of the polyelectrolytes formed on the substrate after adsorption were specific to each of the three pH regimes. [less ▲]

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See detailAnalogy in adsorption behavior of homopolyelectrolyte mixtures as compared to analogous diblock polyampholytes
Mahltig, Boris; Gohy, Jean-François; Jérôme, Robert ULg et al

in Journal of Polymer Science. Part B, Polymer Physics (2002), 40(4), 338-345

The adsorption behavior of aqueous mixtures of the homopolyelectrolytes poly(methacrylic acid) (PMAA) and poly[(dimethylamino)ethyl methacrylate] (PDMAEMA) was investigated in comparison with the ... [more ▼]

The adsorption behavior of aqueous mixtures of the homopolyelectrolytes poly(methacrylic acid) (PMAA) and poly[(dimethylamino)ethyl methacrylate] (PDMAEMA) was investigated in comparison with the adsorption of the ampholytic diblock copolymer PMAA-b-PDMAEMA on silicon substrates. Ellipsometry was used to determine the amount of adsorbed homopolyelectrolyte and diblock polyampholyte. Furthermore, the topography of the adsorbed polymers was investigated with atomic force microscopy (AFM) and compared with the structures observed in aqueous solutions by dynamic light scattering (DLS). For all types of investigated polyelectrolytic mixtures or the single polyampholyte, the adsorption was strongly influenced by the pH of the polymer solution. Although single homopolyelectrolytes showed only one maximum in adsorption according to their charge, the mixtures made from these homopolyelectrolytes showed two or three maxima. The third maximum near the isoelectric point of the mixture was assigned to a new species formed by aggregation of the two homopolyelectrolytes. Altogether, the adsorption behavior of the polyelectrolytic mixtures was in between the behavior of the pure homopolyelectrolytes and the analogous polyampholytes and therefore understandable from both of these polymer species.(C) 2002 John Wiley Sons, Inc. [less ▲]

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See detailHighly regular polyampholytic structures adsorbed directly from solution
Mahltig, Boris; Müller-Buschbaum, P.; Wolkenhauer, M. et al

in Journal of Colloid and Interface Science (2001), 242(1), 36-43

This article concerns the adsorption of the diblock polyampholyte poly(methacrylic acid)-block-poly((dimethylamino)ethyl methary-late) (PMAA-b-PDMAEMA) from aqueous solution on silicon substrates. The ... [more ▼]

This article concerns the adsorption of the diblock polyampholyte poly(methacrylic acid)-block-poly((dimethylamino)ethyl methary-late) (PMAA-b-PDMAEMA) from aqueous solution on silicon substrates. The investigated polyampholyte is characterized by a small molecular weight around 15,000 g/mol and a big positively charged PDMAEMA block. The adsorbed amount determined by ellipsom-etry was str ongly influenced by the pH of the adsorption solution. Using dynamic light scattering polyampholytic structures with diameters around 50 nm were found in aqueous solution. The hy-drodynamic diameter was hardly affected by changing the pH of the polymer solution. Analogous regular structures were also found by scanning force microscopy (SFM) and grazing incidence, small angle X-ray scattering (GISAXS) at the silicon surface after the adsorption process. While SFM provides a topographical image of a small part of the adsorbed polyampholytic layer; GISAXS was used to get a statistical description of the lateral surface structures. The adsorbed structures were highly regular and their sizes were nearly pH independent over a lar ge pH region. Only directly at the isoelectric point of the polyampholyte larger adsorbed structures were observed. Compared with earlier investigated PMAA-b-PDMAEMA systems we are now able to prepare highly regular polyampholytic structures at silicon surfaces. There are two kinds of interactions for the adsorbed micelles. First, the charged block of the chains is directly attracted to the substrate via electrostatic interactions, while the uncharged part of the chains is only hydrophobically attracted via the hydrophobic core of the adsorbed micelle. [less ▲]

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See detailDiblock polyampholytes at the silicon-water interface: adsorption as a function of block ratio and molecular weight
Mahltig, Boris; Gohy, Jean-François; Jérôme, Robert ULg et al

in Journal of Polymer Science. Part B, Polymer Physics (2001), 39(6), 709-718

Polyampholytes are highly charged macromolecules carrying oppositely charged functional groups. This article reports on the adsorption of a weak diblock polyampholyte, poly(methacrylic acid)-block-poly ... [more ▼]

Polyampholytes are highly charged macromolecules carrying oppositely charged functional groups. This article reports on the adsorption of a weak diblock polyampholyte, poly(methacrylic acid)-block-poly[(dimethylamino)ethyl methacrylate], as a function of the copolymer composition and molecular weight. The adsorption experiments were performed on silicon substrates from aqueous polymer solutions at different pHs. The amount of adsorbed polyampholyte chains to the surface was determined by ellipsometry, whereas lateral structures were investigated by scanning force microscopy. A strong influence of pH on the adsorbed amount and the lateral structure formation at the surface was observed. Especially at the isoelectric point, drastic changes in adsorption behavior were detected. At low molecular weights, an increased adsorbed amount was detected, a behavior in contrast to common theoretical predictions. This phenomenon is explained by the high stability of absorbed micelles, which cover the silicon surface as a dense layer. We conclude that micelle formation is an important process for polyampholyte adsorption, which needs to be taken into account more explicitly. [less ▲]

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See detailDiblock polyampholytes at the silicon/water interface: adsorption at various modified silicon substrates
Mahltig, Boris; Jérôme, Robert ULg; Stamm, Manfred

in Physical Chemistry Chemical Physics [=PCCP] (2001), 3(19), 4371-4375

The adsorption behaviour of the ampholytic diblock copolymer poly(methacrylic acid)-block-poly((dimethylamino)ethyl methacrylate), PMAA-b-PDMAEMA, was investigated on differently prepared silicon surfaces ... [more ▼]

The adsorption behaviour of the ampholytic diblock copolymer poly(methacrylic acid)-block-poly((dimethylamino)ethyl methacrylate), PMAA-b-PDMAEMA, was investigated on differently prepared silicon surfaces. All adsorption experiments were performed from aqueous solutions as a function of pH. The polyampholyte amount adsorbed was determined ellipsometrically, while the topographies of the adsorbed polymer were investigated using scanning force microscopy (SFM). Three polyampholyte systems with similar molecular weight around 60000 g mol–1 and different block ratios were adsorbed on three different types of silicon substrates. Depending on the pretreatment the silicon substrates contained different isoelectric points (IEP) and hydrophobicity. The adsorbed amount, as a function of pH, was characterized by maxima and minima near the IEP of the polyampholytes. In the case of polyampholytes containing an IEP close to the IEP of the silicon substrates, the nature of the substrate strongly influenced the adsorption behaviour. Even a complete erasure of one adsorption maximum could be observed in some cases. In contrast to this, polyampholytes with an IEP in a pH area far away from the IEP of the substrates adsorbed in a quite similar manner on the different substrates. [less ▲]

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See detailProtein adsorption on preadsorbed polyampholytic monolayers
Mahltig, Boris; Werner, Carsten; Müller, Martin et al

in Journal of Biomaterials Science. Polymer Edition (2001), 12(9), 995-1010

The adsorption behaviour of five different globular proteins on pure silicon substrates and on preadsorbed polyampholytic monolayers has been investigated as a function of protein concentration. The ... [more ▼]

The adsorption behaviour of five different globular proteins on pure silicon substrates and on preadsorbed polyampholytic monolayers has been investigated as a function of protein concentration. The prelayers were prepared by adsorption of the ampholytic diblock copolymer poly(methacrylic acid)-block-poly ((dimethylamino)ethyl methacrylate) (PMAA-b-PDMAEMA). This polyampholyte adsorbs in densely packed micelles directly from aqueous solution. Ellipsometry was used to determine the amount of adsorbed polyampholyte and protein. While ATR-IR spectroscopy gives information about the adsorption and desorption behaviour of the preadsorbed polyampholytic layer, the lateral structures of the dried films were investigated by scanning force microscopy (SFM). The amount of protein adsorbed was found to be strongly influenced by the preadsorbed polyampholyte compared to the adsorption on the pure silicon substrates. No displacement of the polyampholyte by the proteins was detected. In most cases the protein adsorption was reduced by the preadsorbed polyampholytic layer. The observed trends are explained by the change in electrostatic and hydrophilic characteristics of the substrates. Furthermore, the entropy of adsorption has to be taken into account. [less ▲]

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See detailSurface structure of thin film blends of polystyrene and poly(n-butyl methacrylate)
Affrossman, S.; Jérôme, Robert ULg; O'Neill, S. A. et al

in Colloid and Polymer Science (2000), 278(10), 993-999

Thin films of blends of polystyrene (PS) and poly(n-butyl methacrylate) (PBMA) were prepared by spin-casting onto silicon wafers in order to map the lateral distribution of the two polymers. The surfaces ... [more ▼]

Thin films of blends of polystyrene (PS) and poly(n-butyl methacrylate) (PBMA) were prepared by spin-casting onto silicon wafers in order to map the lateral distribution of the two polymers. The surfaces were examined by atomic force microscopy (AFM) secondary ion mass spectroscopy X-ray photoelectron spectroscopy (XPS) and photoemission electron microscopy (PEEM). Films with PBMA contents of 50% w/w or less were relatively smooth, but further increase in the PBMA content produced, initially, protruding PS ribbons and then, for PBMA ≥80% w/w, isolated PS islands. At all concentrations the topmost surface (0.5-1.0 nm) was covered by PBMA, whilst the PBMA concentration in the near-surface region, measured by XPS, increased with bulk content to eventual saturation. PEEM measurements of a PS-PBMA film at the composition at which ribbon features were observed by AFM also showed a PS-rich ribbon structure surrounded by a sea of mainly PBMA. [less ▲]

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See detailAggregates formed by amphoteric diblock copolymers in water
Gohy, Jean-François; Creutz, Serge; Garcia, Myriam et al

in Macromolecules (2000), 33(17), 6378-6387

The associating behavior of a series of monodisperse poly(2-(dimethylamino)ethyl methacrylate)-b-poly(methacrylic acid) (PDMAEMA-b-PMAA) ampholytic diblock copolymers has been studied in water in the ... [more ▼]

The associating behavior of a series of monodisperse poly(2-(dimethylamino)ethyl methacrylate)-b-poly(methacrylic acid) (PDMAEMA-b-PMAA) ampholytic diblock copolymers has been studied in water in the dilute regime as a function of pH and salt concentration. Dynamic light scattering (DLS) has been used to monitor the association behavior and transmission electron microscopy (TEM) to visualize the morphology of the aggregates. At and around the isoelectric point (IEP) of the ampholytic diblocks, strong electrostatic interactions occur and lead to the formation of insoluble complexes between negatively and positively charged blocks. These electrostatic interactions can be screened by the addition of salt, which leads to the partial dissolution of the material, according to Debye screening. For samples containing a major PDMAEMA block, spherical micelles are observed below the IEP. These micelles consist of a PMAA core surrounded by a water-soluble protonated PDMAEMA corona. At and above the IEP, these samples are insoluble. Spherical micelles are also formed below the IEP for samples containing a minor PDMAEMA block. These copolymers are insoluble at and around the IEP, whereas solubility is observed above the IEP with formation of aggregates of remarkable morphologies, including hollow spheres and complex compartmentalized aggregates. This aggregation is most favorable at high pH, and it cannot be accounted for only by electrostatic interaction between oppositely charged blocks. Indeed, short-range hydrophobic interaction between uncharged PDMAEMA blocks seems to play a key role in the association process. This is emphasized by quaternized poly(2-(dimethylamino)ethyl methacrylate)-b-poly(methacrylic acid) ampholytic copolymers which are carrying a permanent positive charge on the aminated monomeric units and do not form these particular aggregates. [less ▲]

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See detailAdsorption kinetics of a hydrophobic-hydrophilic diblock polyelectrolyte at the solid- aqueous solution interface: a slow birth and fast growth process
Abraham, T.; Giasson, S.; Gohy, Jean-François et al

in Macromolecules (2000), 33(16), 6051-6059

The adsorption kinetics of a diblock copolymer poly(tert-butyl methacrylate)-b-poly(glycidyl methacrylate sodium sulfonate) on hydrophobic substrate from aqueous solution under different added monovalent ... [more ▼]

The adsorption kinetics of a diblock copolymer poly(tert-butyl methacrylate)-b-poly(glycidyl methacrylate sodium sulfonate) on hydrophobic substrate from aqueous solution under different added monovalent salt (NaCl) concentrations was investigated using an ellipsometric technique. The effect of monovalent counterion size on adsorption kinetics of the same copolymer on hydrophobic surfaces was also part of the investigation. The results, in general, indicate that the adsorption process on solid surfaces occurs through the anchoring of hydrophobic chains due to the short-ranged hydrophobic interactions. The kinetic data reveal three distinct stages in the adsorption process: an incubation period, a subsequent fast growth process of the polymer layer, and a plateau (equilibrium) region. These three stages are found to be influenced by salt concentration as well as counterion size. The equilibrium adsorption density increases as a function of salt concentration, and the dependence is found to be different from the theoretical predictions. The incubation time increases with salt concentration according to a power law dependence, and a simple bound ionic layer formation on the substrate is proposed as a possible explanation for this observation. An attempt has been made to explain the growth process in terms of an Avrami type ordering process. The Avrami analysis indicates that the buildup of polyelectrolyte layer structure depends on added salt conditions. Our kinetic data suggest that the diffusion of the chains to the surface is not the rate-controlling process for adsorption. A slow birth (nucleation) and fast growth of the layer seem to be the determining adsorption process. [less ▲]

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See detailDeformation behavior of weakly segregated block copolymers. 2. Correlation between phase behavior and deformation mechanisms of diblock copolymers
Weidisch, R.; Schreyeck, G.; Ensslen, M. et al

in Macromolecules (2000), 33(15), 5495-5504

The deformation behavior of poly(styrene-b-butyl methacrylate) diblock copolymers, PS-b-PBMA, is studied by high-voltage electron microscopy (HVEM) with an in-situ tensile device. While in the first part ... [more ▼]

The deformation behavior of poly(styrene-b-butyl methacrylate) diblock copolymers, PS-b-PBMA, is studied by high-voltage electron microscopy (HVEM) with an in-situ tensile device. While in the first part the phase behavior of PS-b-PBMA diblock copolymers is investigated via small-angle neutron scattering (SANS), in the second part the deformation behavior depending on composition and molecular weight is discussed. Disordered block copolymers have the same deformation mechanism as the corresponding homopolymers, while microphase-separated block copolymers undergo a cavitation mechanism. At the order−disorder transition, ODT, a transition from crazing to cavitation mechanism is found via HVEM. Moreover, a sharp increase of the diameter of craze fibrils occurs at the ODT, demonstrating that the craze microstructure is strongly influenced by phase behavior. As the incompatibility increases with increasing molecular weight, deformation mechanisms such as diversion and termination of crazes are observed for intermediately segregated block copolymers. The discussed correlation between phase behavior and deformation mechanisms indicates the existence of a unified scheme for deformation behavior of diblock copolymers depending on the strength of segregation, χN. [less ▲]

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