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  • 1. Abraham, T.
    et al.
    Kumpulainen, A.
    Xu, Z.
    Rutland, Mark W
    KTH, Superseded Departments, Chemistry.
    Claesson, Per M.
    KTH, Superseded Departments, Chemistry.
    Masliyah, J.
    Polyelectrolyte-mediated interaction between similarly charged surfaces: Role of divalent counter ions in tuning surface forces2001In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 17, no 26, p. 8321-8327Article in journal (Refereed)
    Abstract [en]

    The effects of divalent salts (CaCl2, MgCl2 and BaCl2) in promoting the adsorption of weakly charged polyelectrolyte (polyacrylic acid), PAA, Mw similar to 250000 g/mol) on mica surfaces and their role in tuning the nature of interactions between such adsorbed polyelectrolyte layers were studied using the interferometric surface forces apparatus. With mica surfaces in 3 mM MgCl2 solutions at pH similar to8.0-9.0, the addition of 10 ppm PAA resulted in a long-range attractive bridging force and a short-range repulsive steric force. This force profile indicates a low surface coverage and weak adsorption. The range of the force can be related to the characteristic length scale R-G of polyelectrolyte chains using a scaling description. An increase of the PAA concentration to 50 ppm changed the attractive force profile to a monotonic, long-range repulsive interaction extending up to 600 Angstrom due to the increased surface coverage of polyelectrolyte chains on the mica surfaces. Comparison of the measured forces with a scaling mean field model suggests that the adsorbed polyelectrolyte chains are stretched, which eventually give rise to the polyelectrolyte brush like structure. When the mica surfaces were preincubated in 3 mM CaCl2 at pH similar to8.0-9.0, in contrast to the case of 3 MM MgCl2, the addition of 10 ppm PAA resulted in a more complex force profile: long-range repulsive forces extending up to 800 Angstrom followed by an attractive force regime and a second repulsive force regime at shorter separations. The long-range electrosteric forces can be attributed to strong adsorption of polyelectrolyte chains on mica surfaces (high surface coverage) which is facilitated by the presence of Ca2+ ions, while the intermediate range attractive forces can be ascribed to Ca2+ assisted bridging between adsorbed polyelectrolyte chains. Also interesting is to note various relaxation processes present in this system. In contrast to both MgCl2 and CaCl2 systems, with mica surfaces in 3 mM BaCl2 solution at pH similar to8.0-9.0, the addition of 10 ppm PAA resulted in precipitation of polyelectrolyte chains on mica surfaces, resulting in an extremely long-range monotonic repulsive force profile. In summary, our study showed that divalent counterions (Mg2+, Ca2+, and Ba2+) exhibit significantly different behavior in promoting PAA adsorption on mica surfaces, modifying and controlling various surface interactions.

  • 2. Acciaro, Roberta
    et al.
    Aulin, Christian
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Lindström, Tom
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Varga, Imre
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Investigation of the formation, structure and release characteristics of self-assembled composite films of cellulose nanofibrils and temperature responsive microgels2011In: Soft Matter, ISSN 1744-683X, Vol. 7, no 4, p. 1369-1377Article in journal (Refereed)
    Abstract [en]

    The possibility of forming self-organized films using charge-stabilized dispersions of cellulose I nanofibrils and microgel beads of poly-(N-isopropylacrylamide-co-acrylic acid) copolymer is presented. The build-up behavior and the properties of the layer-by-layer (LbL)-constructed films were studied using quartz crystal microbalance with dissipation (QCM-D) and ellipsometry. The morphology of the formed films was also characterized using atomic force microscopy (AFM) imaging. The applied methods clearly demonstrated the successful LbL-assembly of the monodisperse microgels and nanofibrils. The in situ QCM-D measurements also revealed that contrary to the polyelectrolyte bound microgel particles, the nanofibrils-bound gel beads preserve their highly swollen state and do not suffer a partial collapse due to the lack of interdigitation of the oppositely charged components. To probe the accessibility of the gel beads in the formed films, the room temperature (similar to 25 degrees C) loading and release of a fluorescent dye (FITC) was also investigated. The incorporation of the cellulose nanofibrils into the multilayer resulted in an open structure that was found easily penetrable for the dye molecules even at constant room temperature, which is in sharp contrast with previously reported systems based on synthetic polyelectrolytes. The amount of dye released from the multilayer films could be fine-tuned with the number of bilayers. Finally, the thermoresponsivity of the films was also shown by triggering the burst release of the loaded dye when the film was collapsed.

  • 3.
    Adhikari, Arindam
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Pani, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Deidinaitei, Andra
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Blomberg, Eva
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Electrochemical behavior and anticorrosion properties of modified polyaniline dispersed in polyvinylacetate coating on carbon steel2008In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 53, no 12, p. 4239-4247Article in journal (Refereed)
    Abstract [en]

    Conducting polyaniline (Pani) was prepared in the presence of methane sulfonic acid (MeSA) as dopant by chemical oxidative polymerization. The Pani-MeSA polymer was characterized by FT-IR, UV-vis, X-ray diffraction (XRD) and impedance spectroscopy. The polyrner was dispersed in polyvinylacetate and coated oil carbon steel samples by a dipping method. The electrochemical behavior and anticorrosion properties of the coating, oil carbon steel in 3% NaCl were investigated using Open-circuit Potential (OCP) versus time of exposure, and electrochemical techniques including electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and cyclic voltammetry (CV). During initial exposure, the OCP dropped about 0.35 V and the interfacial resistance increased several times, indicating I certain reduction of the polymer and oxidation of the steel surface. Later the OCP shifted to the noble direction and remained at a stable value during the exposure up to 60 days. The EIS monitoring also revealed the initial change and later stabilization of the coating. The stable high OCP and low coating impedance Suggest that the conducting polymer maintains its oxidative state and provides corrosion protection for carbon steel through out the investigated period. The polarization curves and CV show that the conducting polymer coating induces a passive-like behavior and greatly reduces the corrosion of carbon steel.

  • 4.
    An, Junxue
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Dèdinaitè, Andra
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Winnik, Francoise M.
    Qiu, Xing-Ping
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Temperature-Dependent Adsorption and Adsorption Hysteresis of a Thermoresponsive Diblock Copolymer2014In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 30, no 15, p. 4333-4341Article in journal (Refereed)
    Abstract [en]

    A nonionic-cationic diblock copolymer, poly(2-isopropyl-2-oxazoline)(60)-b-poly((3-acrylamidopropyl)- trimethylammonium chloride)(17), (PIPOZ(60)-b-PAMPTMA(17)), was utilized to electrostatically tether temperature-responsive PIPOZ chains to silica surfaces by physisorption. The effects of polymer concentration, pH, and temperature on adsorption were investigated using quartz crystal microbalance with dissipation monitoring and ellipsometry. The combination of these two techniques allows thorough characterization of the adsorbed layer in terms of surface excess, thickness, and water content. The high affinity of the cationic PAMPTMA(17) block to the negatively charged silica surface gives rise to a high affinity adsorption isotherm, leading to (nearly) irreversible adsorption with respect to dilution. An increase in solution pH lowers the affinity of PIPOZ to silica but enhances the adsorption of the cationic block due to increasing silica surface charge density, which leads to higher adsorption of the cationic diblock copolymer. Higher surface excess is also achieved at higher temperatures due to the worsening of the solvent quality of water for the PIPOZ block. Interestingly, a large hysteresis in adsorbed mass and other layer properties was observed when the temperature was cycled from 25 to 45 degrees C and then back to 25 degrees C. Possible causes for this temperature hysteresis are discussed.

  • 5.
    An, Junxue
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Dédinaité, Andra
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Nilsson, Anki
    Holgersson, Jan
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Comparison of a Brush-with-Anchor and a Train-of-Brushes Mucin on Poly(methyl methacrylate) Surfaces: Adsorption, Surface Forces, and Friction2014In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 15, no 4, p. 1515-1525Article in journal (Refereed)
    Abstract [en]

    Interfacial properties of two types of mucins have been investigated at the aqueous solution/poly(methyl methacrylate) (PMMA) interface. One is commercially available bovine submaxillary mucin, BSM, which consists of alternating glycosylated and nonglycosylated regions. The other one is a recombinant mucin-type fusion protein, PSGL-1/mIgG(2b), consisting of a glycosylated mucin part fused to the Fc part of an immunoglobulin. PSGL-1/mIgG(2b) is mainly expressed as a (timer upon production. A quartz crystal microbalance with dissipation was used to study the adsorption of the mucins to PMMA surfaces. The mass of the adsorbed mucin layers, including the adsorbed mucin and water trapped in the layer, was found to be significantly higher for PSGL-1/mIgG(2b) than for BSM. Atomic force microscopy with colloidal probe was employed to study interactions and frictional forces between mucin-coated PMMA surfaces. Purely repulsive forces of steric origin were Observed between PSGL-1/mIgG(2b) mucin layers, whereas a small adhesion was detected between BSM layers and attributed to bridging. Both mucin layers reduced the friction force between PMMA surfaces in aqueous solution. The reduction was, however, significantly more pronounced for PSGL-1/mIgG(2b). The effective friction coefficient between PSGL-1/mIgG(2b)-coated PMMA surfaces is as low as 0.02 at low loads, increasing to 0.24 at the highest load explored, 50 nN. In contrast, a friction coefficient of around 0.7 was obtained between BSM-coated PMMA surfaces. The large differences in interfacial properties for the two mucins are discussed in relation to their structural differences.

  • 6.
    An, Junxue
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Jin, Chunsheng
    Dedinaite, Andra
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP Technical Research Institute of Sweden.
    Holgersson, Jan
    Karlsson, Niclas G.
    Claesson, Per Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP Technical Research Institute of Sweden.
    Influence of Glycosylation on Interfacial Properties of Recombinant Mucins: Adsorption, Surface Forces, and Friction2017In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 33, no 18, p. 4386-4395Article in journal (Refereed)
    Abstract [en]

    Interfacial properties of two brush-with-anchor mucins, C-P55 and C-PSLex, have been investigated at the aqueous solution/poly(methyl methacrylate) (PMMA) interface. Both are recombinant mucin-type fusion proteins, produced by fusing the glycosylated mucin part of P-selectin glycoprotein ligand-1 (PSLG-1) to the Fc part of a mouse immunoglobulin in two different cells. They are mainly expressed as dimers upon production. Analysis of the O-glycans shows that the C-PSLex mucin has the longer and more branched side chains, but C-P55 has slightly higher sialic acid content. The adsorption of the mucins to PMMA surfaces was studied by quartz crystal microbalance with dissipation. The sensed mass, including the adsorbed mucin and water trapped in the layer, was found to be similar for these two mucin layers. Atomic force microscopy with colloidal probe was employed to study surface and friction forces between mucin-coated PMMA surfaces. Purely repulsive forces of steric origin were observed between mucin layers on compression, whereas a small adhesion was detected between both mucin layers on decompression. This was attributed to chain entanglement. The friction force between C-PSLex-coated PMMA is lower than that between C-P55-coated PMMA. at low loads, but vice versa at high loads. We discuss our results in terms of the differences in the glycosylation composition of these two mucins.

  • 7.
    An, Junxue
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Jin, Chunsheng
    Dėdinaitė, Andra
    Holgerssond, Jan
    Karlssonb, Niclas G.
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Influence of Glycosylation on Interfacial Properties of Recombinant Mucins: Adsorption, Surface Forces and FrictionManuscript (preprint) (Other academic)
    Abstract [en]

    Interfacial properties of two brush-with-anchor mucins, C-P55 and C-PSLex, have been investigated at the aqueous solution/poly(methylmethacrylate) (PMMA) interface. Both are recombinant mucin-type fusion proteins, produced by fusing the glycosylated mucin part of P-selectin glycoprotein ligand-1 (PSLG-1) to the Fc part of a mouse immunoglobulin in two different cells. They are mainly expressed as dimers upon production. Analysis of the O-glycans shows that the C-PSLex mucin has the longer and more branched side chains, but C-P55 has slightly higher sialic acid content. The adsorption of the mucins to PMMA surfaces was studied by quartz crystal microbalance with dissipation. The sensed mass, including the adsorbed mucin and water trapped in the layer, was found to be similar for these two mucin layers. Atomic force microscopy with colloidal probe was employed to study surface and friction forces between mucin-coated PMMA surfaces. Purely repulsive forces of steric origin were observed between mucin layers on compression, whereas a small adhesion was detected between both mucin layers on decompression. This was attributed to chain entanglement. The friction force between C-PSLex-coated PMMA is lower than that between C-P55-coated PMMA at low loads, but vice versa at high loads. We discuss our results in terms of the differences in the glycosylation composition of these two mucins.

  • 8.
    An, Junxue
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Liu, Xiaoyan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Dédinaité, Andra
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP Technical Research Institute of Sweden.
    Korchagina, Evgeniya
    Winnik, Francoise M.
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP Technical Research Institute of Sweden.
    Effect of solvent quality and chain density on normal and frictional forces between electrostatically anchored thermoresponsive diblock copolymer layers2017In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 487, p. 88-96Article in journal (Refereed)
    Abstract [en]

    Equilibration in adsorbing polymer systems can be very slow, leading to different physical properties at a given condition depending on the pathway that was used to reach this state. Here we explore this phenomenon using a diblock copolymer consisting of a cationic anchor block and a thermoresponsive block of poly(2-isopropyl-2-oxazoline), PIPOZ. We find that at a given temperature different polymer chain densities at the silica surface are achieved depending on the previous temperature history. We explore how this affects surface and friction forces between such layers using the atomic force microscope colloidal probe technique. The surface forces are purely repulsive at temperatures <40 degrees C. A local force minimum at short separation develops at 40 degrees C and a strong attraction due to capillary condensation of a polymer-rich phase is observed close to the bulk phase separation temperature. The friction forces decrease in the cooling stage due to rehydration of the PIPOZ chain. A consequence of the adsorption hysteresis is that the friction forces measured at 25 degrees C are significantly lower after exposure to a temperature of 40 degrees C than prior to heating, which is due to higher polymer chain density on the surface after heating.

  • 9.
    An, Junxue
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Liu, Xiaoyan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Linse, Per
    Dedinaite, Andra
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. SP Technical Research Institute of Sweden, Sweden .
    Winnik, Francoise M.
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Tethered Poly(2-isopropyl-2-oxazoline) Chains: Temperature Effects on Layer Structure and Interactions Probed by AFM Experiments and Modeling2015In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 31, no 10, p. 3039-3048Article in journal (Refereed)
    Abstract [en]

    Thermoresponsive polymer layers on silica surfaces have been obtained by utilizing electrostatically driven adsorption of a cationic-nonionic diblock copolymer. The cationic block provides strong anchoring to the surface for the nonionic block of poly(2-isopropyl-2-oxazoline), referred to as PIPOZ. The PIPOZ chain interacts favorably with water at low temperatures, but above 46 degrees C aqueous solutions of PIPOZ phase separate as water becomes a poor solvent for the polymer. We explore how a change in solvent condition affects interactions between such adsorbed layers and report temperature effects on both normal forces and friction forces. To gain further insight, we utilize self-consistent lattice mean-field theory to follow how changes in temperature affect the polymer segment density distributions and to calculate surface force curves. We find that with worsening of the solvent condition an attraction develops between the adsorbed PIPOZ layers, and this observation is in good agreement with predictions of the mean-field theory. The modeling also demonstrates that the segment density profile and the degree of chain interpenetration under a given load between two PIPOZ-coated surfaces rise significantly with increasing temperature.

  • 10.
    An, Junxue
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Zander, Thomas
    Liu, Xiaoyan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Linse, Per
    Dédinaité, Andra
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP Technical Research Institute of Sweden.
    Winnik, Francoise M.
    Qiu, Xing-Ping
    Claesson, Per Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP Technical Research Institute of Sweden.
    Tethered Poly(2-Isopropyl-2-Oxazoline) Chai: Temperature Effects of Layer Structure and Interactions Probed by AFM Experiments and ModelingManuscript (preprint) (Other academic)
  • 11.
    Aulin, Christian
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Varga, Imre
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Claesson, Per
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Lindström, Tom
    STFI-Packforsk AB.
    Buildup of Polyelectrolyte Multilayers of Polyethyleneimine and Microfibrillated Cellulose Studied by in situ Dual Polarization Interferometry and Quartz Crystal Microbalance with Dissipation2008In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 24, no 6, p. 2509-2518Article in journal (Refereed)
    Abstract [en]

    Polyethyleneimine (PEI) and Microfibrillated cellulose (MFC) have been used to buildup polyelectrolyte multilayers (PEM) on silicone oxide and silicone oxynitride surfaces at different pH values and with different electrolyte and polyelectrolyte/colloid concns. of the components.  Consecutive adsorption on these surfaces was studied by in situ dual-polarization interferometry (DPI) and quartz crystal microbalance measurements.  The adsorption data obtained from both the techniques showed a steady buildup of multilayers.  High pH and electrolyte concn. of the PEI soln. was found to be beneficial for achieving a high adsorbed amt. of PEI, and hence of MFC, during the buildup of the multilayer.  On the other hand, an increase in the electrolyte concn. of the MFC dispersion was found to inhibit the adsorption of MFC onto PEI.  The adsorbed amt. of MFC was independent of the bulk MFC concn. in the investigated concn. range (15-250 mg/L).  At. force microscopy measurements were used to image a MFC-treated silicone oxynitride chip from DPI measurements.  The surface was found to be almost fully covered by randomly oriented microfibrils after the adsorption of only one bilayer of PEI/MFC.  The surface roughness expressed as the rms-roughness over 1 μm2 was calcd. to be 4.6 nm (1 bilayer).  The adsorbed amt. of PEI and MFC and the amt. of water entrapped by the individual layers in the multilayer structures were estd. by combining results from the two anal. techniques using the de Feijter formula.  These results indicate a total water content of ca. 41% in the PEM.

  • 12. Bain, C. D.
    et al.
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Langevin, D.
    Meszaros, R.
    Nylander, T.
    Stubenrauch, C.
    Titmuss, S.
    von Klitzing, R.
    Complexes of surfactants with oppositely charged polymers at surfaces and in bulk2010In: Advances in Colloid and Interface Science, ISSN 0001-8686, E-ISSN 1873-3727, Vol. 155, no 1-2, p. 32-49Article in journal (Refereed)
    Abstract [en]

    Addition of surfactants to aqueous solutions of polyelectrolytes carrying an opposite charge causes the spontaneous formation of complexes in the bulk phase in certain concentration ranges. Under some conditions, compact monodisperse multichain complexes are obtained in the bulk. The size of these complexes depends on the mixing procedure and it can be varied in a controlled way from nanometers up to micrometers. The complexes exhibit microstructures analoguous to those of the precipitates formed at higher concentrations. In other cases, however, the bulk complexes are large, soft and polydisperse. In most cases, the dispersions are only kinetically stable and exhibit pronounced non-equilibrium features. Association at air-water interfaces readily occurs, even at very small concentrations. When the surfactant concentration is small, the surface complexes are usually made of a surfactant monolayer to which the polymer binds and adsorbs in a flat-like configuration. However, under some conditions, thicker layers can be found, with bulk complexes sticking to the surface. The association at solid-water interfaces is more complex and depends on the specific interactions between surfactants, polymers and the surface. However, the behaviour can be understood if distinctions between hydrophilic surfaces and hydrophobic surfaces are made. Note that the behaviour at air-water interfaces is closer to that of hydrophobic than that of hydrophilic solid surfaces. The relation between bulk and surface complexation will be discussed in this review. The emphasis will be given to the results obtained by the teams of the EC-funded Marie Curie RTN "SOCON".

  • 13. Bartenstein, J. E.
    et al.
    Liu, Xiaoyan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Lange, K.
    Claesson, Per Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Briscoe, W. H.
    Polymersomes at the solid-liquid interface: Dynamic morphological transformation and lubrication2018In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 512, p. 260-271Article in journal (Refereed)
    Abstract [en]

    Polymersomes are hollow spheres self-assembled from amphiphilic block copolymers of certain molecular architecture. Whilst they have been widely studied for biomedical applications, relatively few studies have reported their interfacial properties. In particular, lubrication by polymersomes has not been previously reported. Here, interfacial properties of polymersomes self-assembled from poly(butadiene)-poly(ethylene oxide) (PBD-PEO; molecular weight 10,400 g mol−1) have been studied at both hydrophilic and hydrophobic surfaces. Their morphology at silica and mica surfaces was imaged with quantitative nanomechanical property mapping atomic force microscopy (QNM AFM), and friction and surface forces they mediate under confinement between two surfaces were studied using colloidal probe AFM (CP-AFM). We find that the polymersomes remained intact but adopted flattened conformation once adsorbed to mica, with a relatively low coverage. However, on silica these polymersomes were unstable, rupturing to form donut shaped residues or patchy bilayers. On a silica surface hydrophobized with a 19 nm polystyrene (PS) film, the polymer vesicles formed a more stable layer with a higher surface coverage as compared to the hydrophilic surface, and the interfacial structure also evolved over time. Moreover, friction was greatly reduced on hydrophobized silica surfaces in the presence of polymersomes, suggesting their potential as effective aqueous lubricants.

  • 14.
    Bastardo Zambrano, Luis Alejandro
    et al.
    KTH, Superseded Departments, Chemistry.
    Claesson, Per Martin
    KTH, Superseded Departments, Chemistry.
    Brown, W.
    Department of Physical Chemistry, University of Uppsala,.
    Interactions between mucin and alkyl sodium sulfates in solution: a light scattering study2002In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 18, no 10, p. 3848-3853Article in journal (Refereed)
    Abstract [en]

    The properties of negatively charged mucin in aqueous solutions and its interaction with anionic sodium alkyl sulfates with different hydrocarbon chain lengths were studied by means of dynamic light scattering. It was observed that mucin forms aggregates in aqueous solutions with a hydrodynamic radius above 500 nm. These aggregates dissolve when sodium dodecyl sulfate or sodium decyl sulfate is present at sufficiently high concentration, above about 0.2 cmc (critical micellar concentration). On the other hand, sodium octyl sulfate is not very effective in dissolving the mucin aggregates. The hydrodynamic radius of the dissolved mucin, decorated with some associated surfactant, is found to be in the range of 40-90 nm. The observation that the dissolving power of the sodium alkyl sulfates decreases with decreasing surfactant chain length suggests that the association between the surfactant and mucin is hydrophobically driven. The kinetics of the dissolution process depends on the surfactant concentration, a higher surfactant concentration giving rise to a more rapid dissolution of the aggregates. It was also observed that when the ionic strength is increased, the surfactant concentration needed to dissolve the mucin aggregates decreases. This can be explained by reduction of repulsive electrostatic forces by the salt.

  • 15.
    Bastardo Zambrano, Luis Alejandro
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Garamus, V. M.
    GKSS Research Centre, Geesthacht.
    Bergström, Lars Magnus
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    The structures of complexes between polyethylene imine and sodium dodecyl sulfate in D2O: a scattering study2005In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 109, no 1, p. 167-174Article in journal (Refereed)
    Abstract [en]

    The association between a highly branched polyelectrolyte with ionizable groups, polyethylene imine (PEI), and an anionic surfactant, sodium dodecyl sulfate (SDS), has been investigated at two pH values, using small-angle neutron and light scattering. The scattering data allow us to obtain a detailed picture of the association structures formed. Small-angle neutron scattering (SANS) measurements in solutions containing highly charged PEI at low pH and low SDS concentrations indicate the presence of disklike aggregates. The aggregates change to a more complex three-dimensional structure with increasing surfactant concentration. One pronounced feature in the scattering curves is the presence of a Bragg-like peak at high q-values observed at a surfactant concentration of 4.2 mM and above. This scattering feature is attributed to the formation of a common well-ordered PEI/SDS structure, in analogue to what has been reported for other polyelectrolyte-surfactant systems. Precipitation occurred at the charge neutralization point, and X-ray diffraction measurements on the precipitate confirmed the existence of an ordered structure within the PEI/SDS aggregates, which was identified as a lamellar internal organization. Polyethylene imine has a low charge density in alkaline solutions. At pH 10.1 and under conditions where the surfactant was contrast matched, the SANS scattering curves showed only small changes with increasing surfactant concentration. This suggests that the polymer acts as a template onto which the surfactant molecules aggregate. Data from both static light scattering and SANS recorded under conditions where SDS and to a lower degree PEI contribute to the scattering were found to be consistent with a structure of stacked elliptic bilayers. These structures increased in size and became more compact as the surfactant concentration was increased up to the charge neutralization point.

  • 16.
    Bastardo Zambrano, Luis Alejandro
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Iruthayaraj, Joseph
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Lundin, Maria
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Dédinaité, Andra
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Vareikis, Aušvydas
    Department of Polymer Chemistry, Vilnius University.
    Makuška, Ričardas
    Department of Polymer Chemistry, Vilnius University.
    van der Wal, Albert
    Lever Faberage Europe Global Technology Centre, Unilever R and D.
    Furó, István
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Garamus, Vasil M.
    GKSS Research Centre.
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Soluble complexes in aqueous mixtures of low charge density comb polyelectrolyte and oppositely charged surfactant probed by scattering and NMR2007In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 312, no 1, p. 21-33Article in journal (Refereed)
    Abstract [en]

    A low charge density polyelectrolyte with a high graft density of 45 units long poly(ethylene oxide) side-chains has been synthesized. In this comb polymer, denoted PEO(45)MEMA:METAC-2, 2 mol% of the repeating methacrylate units in the polymer backbone carry a permanent positive charge and the remaining 98 mol% a 45 unit long PEO side-chain. Here we describe the solution conformation of this polymer and its association with an anionic surfactant, sodium dodecylsulfate, SDS. It will be shown that the polymer can be viewed as a stiff rod with a cross-section radius of gyration of 29 A. The cross section of the rod contracts with increasing temperature due to decreased solvency of the PEO side-chains. The anionic surfactant associates to a significant degree with PE045MEMA:METAC-2 to form soluble complexes at all stoichiometries. A cooperative association is observed as the free SDS concentration approaches 7 mM. At saturation the number of SDS molecules associated with the polymer amounts to 10 for each PEO side-chain. Two distinct populations of associated surfactants are observed, one is suggested to be molecularly distributed over the comb polymer and the other constitutes small micellar-like structures at the periphery of the aggregate. These conclusions are reached based on results from small-angle neutron scattering, static light scattering, NMR, and surface tension measurements.

  • 17.
    Bastardo Zambrano, Luis Alejandro
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Mészaros, R.
    Department of Colloid Chemistry, Eötvös Loránd University, Budapest.
    Varga, I.
    Department of Colloid Chemistry, Eötvös Loránd University, Budapest.
    Gilanyi, T.
    Department of Colloid Chemistry, Eötvös Loránd University, Budapest.
    Claesson, Per Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Deuterium isotope effects on the interaction between hyperbranched polyethylene imine and an anionic surfactant2005In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 109, no 33, p. 16196-16202Article in journal (Refereed)
    Abstract [en]

    Solvent isotope effects on the interaction between the hyperbranched cationic polyelectrolyte, polyethylene imine (PEI), and the anionic surfactant sodium dodecyl sulfate (SDS) were investigated using potentiometric titration and eletrophoretic mobility measurements. In the basic pH range, a significantly higher fraction of the amine groups was found to be protonated when the PEI was dissolved in D2O compared to H2O at the same pH/pD. The difference in polymer charge in the two solvents decreases gradually with decreasing pH, and it completely diminishes at around pH = 4. Electrophoretic mobility measurements of PEI/SDS complexes at different pH values correlated very well with these observations. At pH/pD approximate to 9 a much higher mobility of the PEI/SDS complexes was found in D2O than in H2O at low surfactant concentrations, and the charge neutralization point shifted to a considerably larger surfactant concentration in heavy water. These results can be explained by the significantly higher charge density of the PEI in D2O compared to H2O. However, at the natural pH/pD as well as at pH = 4 and pD = 4 conditions the PEI molecules have roughly equal charge densities, which result in very similar charged characteristics (mobilities) of the PEI/SDS complexes as well as the same charge neutralization SDS concentration. It can be concluded that extreme care must be taken in the general analysis of those experiments in which weak polyelectrolyte/surfactant aggregates are investigated in heavy water, and then these observations are correlated with structures of the same system in water.

  • 18. Baverback, Petra
    et al.
    Oliveira, Cristiano L. P.
    Garamus, Vasil M.
    Varga, Imre
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Pedersen, Jan Skov
    Structural Properties of beta-Dodecylmaltoside and C12E6 Mixed Micelles2009In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 25, no 13, p. 7296-7303Article in journal (Refereed)
    Abstract [en]

    Mixed micelles formed in aqueous solutions of nonionic surfactants n-dodecyl-hexaethylene-glycol (C12E6) and n-dodecyl-beta-D-maltoside (C(12)G(2)) have been studied using small-angle neutron and X-ray scattering (SANS and SAXS) and static light scattering (SLS). Apparent micelle molar masses obtained with SLS were analyzed with a model taking into account both micelle growth and interference effects. The analysis shows that pure C(12)G(2) forms small globular micelles whereas C12E6 and the mixtures form elongated micelles of much higher molar mass. The elongated micelles grow with increased concentration according to mean-field theory, and the masses are larger for increasing amounts of C12E6. To describe the SANS and SAXS data for C12E6 and the mixtures, it: was necessary to employ a model with coexisting spherical and spherocylindrical micelles. The SANS and SAXS data were fitted simultaneously using this model with core-shell particles and molecular constraints. All mixtures, as well as pure C12E6, can be described by this model, demonstrating the coexistence of spherical and cylindrical micelles. The spherical micelles are the same size in all samples, whereas the cylindrical micelles grow in length with the fraction of C12E6 in the samples, as well as with concentration, in agreement with the SLS analysis. The mass fraction of surfactant in cylindrical aggregates also increases with the fraction of C12E6 and with overall concentration. The analysis of the SAXS and SANS data for pure C(12)G(2) shows that the micelles are disk-shaped. The presence of elongated micelles in pure C12E6 and in the mixtures demonstrates that the behavior of the mixtures is dominated by C12E6.

  • 19. Bergeron, V.
    et al.
    Claesson, Per M.
    KTH, Superseded Departments, Chemistry.
    Structural forces reflecting polyelectrolyte organization from bulk solutions and within surface complexes2002In: Advances in Colloid and Interface Science, ISSN 0001-8686, E-ISSN 1873-3727, Vol. 96, no 03-jan, p. 1-20Article in journal (Refereed)
    Abstract [en]

    The interactions between two macroscopic surfaces approaching one another underlies many of the phenomena observed in Colloid and Interface science. In Russia this gave rise to the branch of colloid science now referred to as Surface Forces. Important discoveries, such as the molecular organization of solvent molecules at an interface, have been unveiled by surface force measurements. More recently, forces and structures at macromolecular length scales have been uncovered. In particular, oscillatory force profiles have been detected from aqueous solutions containing polyelectrolytes. The force-structure relationship can reflect organization in the bulk solution or the internal structure of the adsorbed layer. Using a range of surface force techniques, combined with X-ray and neutron scattering results, we review the main features of these fascinating systems and provide an overview of how they relate to other systems such as micellar solutions, polymer-surfactant complexes and simple solvents.

  • 20.
    Bergström, Lars Magnus
    et al.
    KTH, Superseded Departments, Chemistry.
    Kjellin, Mikael
    KTH, Superseded Departments, Chemistry.
    Claesson, Per M.
    KTH, Superseded Departments, Chemistry.
    Grillo, I.
    Small-angle neutron scattering study of mixtures of cationic polyelectrolyte and anionic surfactant: Effect of polyelectrolyte charge density2004In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 108, no 6, p. 1874-1881Article in journal (Refereed)
    Abstract [en]

    We have studied mixtures of an anionic surfactant (deuterated sodium dodecyl sulfate, SDS-d) and cationic polyelectrolytes with different charge densities (10%, 30%, 60%, and 100%) using small-angle neutron scattering (SANS). Near compositions corresponding to charge neutralization, the solutions phase separate into a complex phase (precipitate) consisting of, in the cases of 30%, 60%, and 100% charge density, a two-dimensional (213) hexagonal lattice of close-packed cylindrical micelles and a clear liquid. When either polyelectrolyte with charge density less than 100% or SDS-d is present in sufficient excess, the solution becomes clear and isotropic, and from the scattering data we may conclude that prolate or rod-shaped micelles are present. The micelles are seen to grow in length with increasing SDS-d concentration and polyelectrolyte charge density from about 80 Angstrom to 550 Angstrom, whereas the cross-sectional radius is 15 Angstrom and approximately constant. The number of micelles per polyelectrolyte chain is found to be slightly larger than unity (1-6). In some of the (turbid) samples rod-shaped micelles are found to coexist with larger polyelectrolyte-surfactant complexes. Solutions consisting of 10% charged polyelectrolyte and SDS-d are very viscous and gellike, and the complex phase is much less defined with a much larger distance between adjacent aggregates in the complex phase.

  • 21.
    Bergström, Lars Magnus
    et al.
    KTH, Superseded Departments, Chemistry.
    Kjellin, U. R. M.
    Claesson, Per M
    KTH, Superseded Departments, Chemistry.
    Pedersen, J. S.
    Nielsen, M. M.
    A small-angle X-ray scattering study of complexes formed in mixtures of a cationic polyelectrolyte and an anionic surfactant2002In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 106, no 44, p. 11412-11419Article in journal (Refereed)
    Abstract [en]

    The internal structure of the solid phase formed in mixtures of the anionic surfactant sodium dodecyl sulfate (SDS) and a range of oppositely charged polyelectrolytes with different side chains and charge density has been investigated using small-angle X-ray scattering. Polyelectrolytes with short side chains ([3-(2-methylpropionamido)propyl]trimethylammonium chloride, MAPTAC, and poly{[(2-propionyloxy)ethyl]-trimethylammonium chloride}, PCMA) form a 2-dimensional hexagonal structure with SDS, whereas a polyelectrolyte without side chains (poly(vinlyamine), PVAm) forms a lamellar structure. The hexagonal structure of MAPTAC is retained either when a neutral monomer (acrylamide, AM) is included in the polymer backbone to reduce the charge density or when a nonionic surfactant is admixed to the SDS/polyelctrolyte complex.. The unit cell length of AM-MAPTAC increases with decreasing charge density from a=47.7 Angstrom (MAPTAC, 100% charge density) to 58.5 Angstrom (AM-MAPTAC, 30% charge density). The unit cell length in the lamellar SDS/PVAm complex (a=36.1 Angstrom) is significantly smaller than for the different hexagonal structures. It is conjectured that the cylinders in the hexagonal structure and the bilayers in the lamellar structure are based on self-assembled surfactant aggregates with the polyelectrolyte mainly located in the aqueous region adjacent to the charged surfactant headgroups.

  • 22.
    Bijelic, Goran
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Shovsky, Alexander
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Varga, Imre
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Makuska, Ricardas
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry. KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Adsorption characteristics of brush polyelectrolytes on silicon oxynitride revealed by dual polarisation interferometry2010In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 348, p. 189-197Article in journal (Refereed)
    Abstract [en]

    Adsorption properties of bottle-brush polyelectrolytes have been investigated using dual polarization interferometry (DPI), which provides real time monitoring of adsorbed layer thickness and refractive index. The adsorption on silicon oxynitride was carried out from aqueous solution with no added inorganic salt, and the adsorbed polyelectrolyte layer was subsequently rinsed with NaCl solutions of increasing concentration. The bottle-brush polyelectrolytes investigated in this study have different ratios of permanent cationic charged segments and uncharged PEO side chains. Both the cationic groups and the PEO side chains have affinity for silica-like surfaces, and thus contribute to the adsorption process that becomes rather complex. Adsorption properties in water, responses to changes in ionic strength of the surrounding medium, adsorption kinetics and the layer structure are all strongly dependent on the ratio between backbone charges and side chains. The results are interpreted in terms of competitive adsorption of segments with different chemical nature. The adsorption kinetics is relatively fast, taking only tens to hundreds of seconds when adsorbed from dilute 100 ppm solutions. The DPI technique was found to be suitable for studying such rapid adsorption processes, including determination of the initial adsorption kinetics. We expect that the effects observed in this study are of general importance for synthetic and biological polymers carrying segments of different nature.

  • 23.
    Blomberg, Eva
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry (closed 20081231).
    Claesson, Per Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry (closed 20081231).
    Konradsson, Peter
    Department of Physics, Chemistry and Biology, Linköping University.
    Liedberg, Bo
    Department of Physics, Chemistry and Biology, Linköping University.
    Globotriose- and oligo(ethylene glycol)-terminated self-assembled monolayers: Surface forces, wetting, and surfactant adsorption2006In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 22, no 24, p. 10038-10046Article in journal (Refereed)
    Abstract [en]

    A set of oligo( ethylene glycol)-terminated and globotriose-terminated self-assembled monolayers (SAMs) has been prepared on gold substrates. Such model surfaces are well defined and have good stability due to the strong binding of thiols and disulfides to the gold substrate. They are thus very suitable for addressing questions related to effects of surface composition on wetting properties, surface interactions, and surfactant adsorption. These issues are addressed in this report. Accurate wetting tension measurements have been performed as a function of temperature using the Wilhelmy plate technique. The results show that the nonpolar character of oligo( ethylene glycol)-terminated SAMs increases slightly but significantly with temperature in the range 20-55 degrees C. On the other hand, globotriose-terminated SAMs are fully wetted by water at room temperature. Surface forces measurements have been performed and demonstrated that the interactions between oligo( ethylene glycol)-terminated SAMs are purely repulsive and similar to those determined between adsorbed surfactant layers with the same terminal headgroup. On the other hand, the interactions between globotriose-terminated SAMs include a short-range attractive force component that is strongly affected by the packing density in the layer. In some cases it is found that the attractive force component increases with contact time. Both these observations are rationalized by an orientation- and conformation-dependent interaction between globotriose headgroups, and it is suggested that hydrogen-bond formation, directly or via bridging water molecules, is the molecular origin of these effects.

  • 24.
    Blomberg, Eva
    et al.
    KTH, Superseded Departments, Chemistry.
    Poptoshev, Evgeni
    KTH, Superseded Departments, Chemistry.
    Claesson, Per M.
    KTH, Superseded Departments, Chemistry.
    Caruso, F.
    Centre for Nanoscience and Nanotechnology, Department of Chemical and Biomolecular Engineering, The University of Melbourne, Victoria, Australia.
    Surface interactions during polyelectrolyte multilayer buildup. 1. Interactions and layer structure in dilute electrolyte solutions2004In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 20, no 13, p. 5432-5438Article in journal (Refereed)
    Abstract [en]

    We report the investigation of surface forces between polyelectrolyte multilayers of poly(allylamine hydrochloride) (PAH) and poly(styrenesulfonate sodium salt) (PSS) assembled on mica surfaces during film buildup using a surface force apparatus. Up to four polyelectrolyte layers were prepared on each surface ex situ, and the surface interactions were measured in 10(-4) M KBr solutions. The film thickness under high compressive loads (above 2000 muN/m) increased linearly with the number of deposited layers. In all cases, the interaction between identical surfaces at large separations (> 100 Angstrom from contact) was dominated by electrostatic double-layer repulsion. By fitting DLVO theory to the experimental force curves, the apparent double-layer potential of the interacting surfaces was calculated. At shorter separations, an additional non-DLVO repulsion was present due to polyelectrolyte chains extending some distance from the surface into solution, thus generating an electrosteric type of repulsion. Forces between dissimilar multilayers (i.e., one of the multilayers terminated with PSS and the other with PAH) were attractive at large separations (30-400 Angstrom) owing to a combination of electrostatic attraction and polyelectrolyte bridging.

  • 25.
    Blomberg, Eva
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry (closed 20081231).
    Verrall, Ronald
    Department of Chemistry, University of Saskatchewan, Saskatoon, Canada.
    Claesson, Per M
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry (closed 20081231).
    Interactions between adsorbed layers of cationic gemini surfactants2008In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 24, no 4, p. 1133-1140Article in journal (Refereed)
    Abstract [en]

    The forces acting between glass and between mica surfaces in the presence of two cationic gemini surfactants, 1,4 diDDAB (1,4-butyl-bis(dimethyldodecylammonium bromide)) and 1,12 diDDAB (1,12-dodecyl-bis(dimethyldodecylammonium bromide)), have been investigated below the critical micelle concentration (cmc) of the surfactants using two different surface force techniques. In both cases, it was found that a recharging of the surfaces occurred at a surfactant concentration of about 0.1 x cmc, and at all surfactant concentrations investigated repulsive double-layer forces dominated the interaction at large separations. At smaller separations, attractive forces, or regions of separation with (close to) constant force, were observed. This was interpreted as being due to desorption and rearrangement in the adsorbed layer induced by the proximity of a second surface. Analysis of the decay length of the repulsive double-layer force showed that the majority of the gemini surfactants were fully dissociated. However, the degree of ion pair formation, between a gemini surfactant and a bromide counterion, increased with increasing surfactant concentration and was larger for the gemini surfactant with a shorter spacer length.

  • 26.
    Bodvik, Rasmus
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Dédinaité, Andra
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Karlson, Leif
    Bergström, Lars Magnus
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Baverback, Petra
    Pedersen, Jan Skov
    Edward, Katarina
    Karlsson, Göran
    Varga, Imre
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Aggregation and network formation of aqueous methylcellulose and hydroxypropylmethylcellulose solutions2010In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, ISSN 0927-7757, E-ISSN 1873-4359, Vol. 354, no 1-3, p. 162-171Article in journal (Refereed)
    Abstract [en]

    Solution properties of methylcellulose (MC) and hydroxypropylmethylcellulose (HPMC) have been investigated as a function of temperature and concentration using a broad range of experimental techniques. Novelties include the extensive comparison between MC and HPMC solutions as well as the combination of techniques, and the use of Cryo transmission electron microscopy (Cryo-TEM). The correlation between rheology and light scattering results clearly demonstrates the relation between viscosity change and aggregation. Cryo-TEM images show the network structures formed. Viscosity measurements show that for both MC and HPMC solutions sudden changes in viscosity occur as the temperature is increased. The onset temperature for these changes depends on polymer concentration and heating rate. For both MC and HPMC solutions the viscosity on cooling is very different compared to on heating, demonstrating the slow equilibration time. The viscosity changes in MC and HPMC solutions are dramatically different; for MC solutions the viscosity increases by several orders of magnitude when a critical temperature is reached, whereas for HPMC solutions the viscosity decreases abruptly at a given temperature, followed by an increase upon further heating. Light and (SAXS) small-angle X-ray scattering shows that the increase in viscosity, for MC as well as for HPMC solutions, is due to extensive aggregation of the polymers. Light scattering also provides information on aggregation kinetics. The SAXS measurements allow us to correlate aggregation hysteresis to the viscosity hysteresis, as well as to extract some structural information. Cryo-TEM images give novel information that a fibrillar network is formed in MC solutions, and the strong viscosity increase occurs when this network spans the whole solution volume. For HPMC solutions the behaviour is more complex. The decrease in viscosity can be related to the formation of compact objects, and the subsequent increase to formation of fibrillar structures, which are more linear and less entangled than for MC.

  • 27.
    Bodvik, Rasmus
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Karlson, Leif
    Edwards, Katarina
    Eriksson, Jonny
    Thormann, Esben
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Aggregation of Modified Celluloses in Aqueous Solution: Transition from Methylcellulose to Hydroxypropylmethylcellulose Solution Properties Induced by a Low-Molecular-Weight Oxyethylene Additive2012In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 28, no 38, p. 13562-13569Article in journal (Refereed)
    Abstract [en]

    Temperature effects on the viscosity and aggregation behavior of aqueous solutions of three different cellulose ethers-methylcellulose (MC), hydroxypropylmethylcellulose (HPMC), and ethyl(hydroxyethyl)cellulose (EHEC)-were investigated using viscosity and dynamic light scattering measurements as well as cryo-TEM. In all cases, increasing temperature reduces the solvent quality of water, which induces aggregation. It was found that the aggregation rate followed the order EHEC > HPMC > MC, suggesting that cellulose ethers containing some bulky and partially hydrophilic substituents assemble into large aggregates more readly than methylcellulose. This finding is discussed in terms of the organization of the structures formed by the different cellulose ethers. The temperature-dependent association behavior of cellulose ethers was also investigated in a novel way by adding diethyleneglycolmonobutylether (BDG) to methylcellulose aqueous solutions. When the concentration of BDG was at and above 5 wt %, methylcellulose adopted HPMC-like solution behavior. In particular, a transition temperature where the viscosity was decreasing, prior to increasing at higher temperatures, appeared, and the aggregation rate increased. This observation is rationalized by the ability of amphiphilic BDG to accumulate at nonpolar interfaces and thus also to associate with hydrophobic regions of methylcellulose. In effect, BDG is suggested to act as a physisorbed hydrophilic and bulky substituent inducing constraints on aggregation similar to those of the chemically attached hydroxypropyl groups in HPMC and oligo(ethyleneoxide) chains in EHEC.

  • 28.
    Bodvik, Rasmus
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Macakova, Lubica
    Karlson, Leif
    Thormann, Esben
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Temperature-Dependent Competition between Adsorption and Aggregation of a Cellulose Ether-Simultaneous Use of Optical and Acoustical Techniques for Investigating Surface Properties2012In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 28, no 25, p. 9515-9525Article in journal (Refereed)
    Abstract [en]

    Adsorption of the temperature-responsive polymer hydroxypropylmethylcellulose (HPMC) from an aqueous solution onto hydrophobized silica was followed well above the bulk instability temperature (T-2) in temperature cycle experiments. Two complementary techniques, QCM-D and ellipsometry, were utilized simultaneously to probe the same substrate immersed in polymer solution. The interfacial processes were correlated with changes in polymer aggregation and viscosity of polymer solutions, as monitored by light scattering and rheological measurements. The simultaneous use of ellipsometry and QCM-D, and the possibility to follow layer properties up to 80 degrees C, well above the T-2 temperature, are both novel developments. A moderate increase in adsorbed amount with temperature was found below T-2, whereas a significant increase in the adsorbed mass and changes in layer properties were observed around the T-2 temperature where the bulk viscosity increases significantly. Thus, there is a clear correlation between transition temperatures in the adsorbed layer and in bulk solution, and we discuss this in relation to a newly proposed model that considers competition between aggregation and adsorption/deposition. A much larger temperature response above the T-2 temperature was found for adsorbed layers of HPMC than for layers of methyl cellulose. Possible reasons for this are discussed.

  • 29.
    Bodvik, Rasmus
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Thormann, Esben
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Karlson, Leif
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Temperature responsive surface layers of modified celluloses2011In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 13, no 10, p. 4260-4268Article in journal (Refereed)
    Abstract [en]

    The temperature-dependent properties of pre-adsorbed layers of methylcellulose (MC) and hydroxypropylmethylcellulose (HPMC) were investigated on silica and hydrophobized silica surfaces. Three different techniques, quartz crystal microbalance with dissipation monitoring, ellipsometry, and atomic force microscopy imaging, were used, providing complementary and concise information on the structure, mass and viscoelastic properties of the polymer layer. Adsorption was conducted at 25 degrees C, followed by a rinsing step. The properties of such pre-adsorbed layers were determined as a function of temperature in the range 25 degrees C to 50 degrees C. It was found that the layers became more compact with increasing temperature and that this effect was reversible, when decreasing the temperature. The compaction was more prominent for MC, as shown in the AFM images and in the thickness data derived from the QCM analysis. This is consistent with the fact that the phase transition temperature is lower, in the vicinity of 50 degrees C, for MC than for HPMC. The water content of the adsorbed layers was found to be high, even at the highest temperature, 50 degrees C, explored in this investigation.

  • 30.
    Bodvik, Rasmus
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Thormann, Esben
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Karlson, Leif
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Temperature-dependent adsorption of cellulose ethers on silica and hydrophobized silica immersed in aqueous polymer solution2011In: RSC ADVANCES, ISSN 2046-2069, Vol. 1, no 2, p. 305-314Article in journal (Refereed)
    Abstract [en]

    The influence of temperature on adsorption and the adsorbed layer properties of methylcellulose (MC) and hydroxypropylmethylcellulose (HPMC) were investigated on silica and hydrophobized silica surfaces immersed in aqueous polymer solution. To achieve a concise understanding a quartz crystal microbalance with dissipation, ellipsometry, and atomic force microscopy imaging were employed. These techniques provide complimentary information on the structure, mass and viscoelastic properties of the polymer layers. Adsorption was first allowed at 25 degrees C. Next, the temperature was increased step-wise up to 50 degrees C and then decreased again. This procedure highlights the temperature dependence of the adsorbed material, as well as the hysteresis in the adsorption due to temperature cycling. A change in temperature not only affects the adsorbed amount, but also the properties of the layer as illustrated by measurements of its water content, thickness and viscoelasticity.

  • 31.
    Borgani, Riccardo
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Thorén, Per-Anders
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Forchheimer, Daniel
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Dobryden, Illia
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Sah, Si Mohamed
    KTH.
    Claesson, Per Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Haviland, David B.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Background-Force Compensation in Dynamic Atomic Force Microscopy2017In: Physical Review Applied, E-ISSN 2331-7019, Vol. 7, no 6, article id 064018Article in journal (Refereed)
    Abstract [en]

    Background forces are linear long-range interactions of the cantilever body with its surroundings that must be compensated for in order to reveal tip-surface force, the quantity of interest for determining material properties in atomic force microscopy. We provide a mathematical derivation of a method to compensate for background forces, apply it to experimental data, and discuss how to include background forces in simulation. Our method, based on linear-response theory in the frequency domain, provides a general way of measuring and compensating for any background force and it can be readily applied to different force reconstruction methods in dynamic AFM.

  • 32. Brandner, Birgit D.
    et al.
    Hansson, Petra M.
    Swerin, Agne
    Claesson, Per Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Wahlander, Martin
    Schoelkopf, Joachim
    Gane, Patrick A. C.
    Solvent segregation and capillary evaporation at a superhydrophobic surface investigated by confocal Raman microscopy and force measurements2011In: SOFT MATTER, ISSN 1744-683X, Vol. 7, no 3, p. 1045-1052Article in journal (Refereed)
    Abstract [en]

    Wetting of water, a 1 : 1 water/ethanol mixture and an aqueous dodecylbenzene sulfonic acid surfactant solution on hydrophobic and superhydrophobic surfaces were studied using confocal Raman microscopy. The superhydrophobic surfaces were prepared by immersion of a glass substrate in a silica particle/fluoropolymer formulation followed by silanization. Preparation of hydrophobic surfaces was done in the same way with the exception that the silica particles were excluded from the formulation. The hydrophobic and superhydrophobic surfaces were characterized with respect to surface roughness using AFM, and by contact angle measurements using different liquids. Confocal Raman microscopy measurements in a 1 : 1 water/ethanol mixture showed an enrichment of ethanol close to the superhydrophobic surface, which could not be observed for the hydrophobic surface. Unexpectedly, the Raman spectrum of a pure water film in close proximity to the superhydrophobic surface displayed some differences compared to that of bulk water and indicated a stronger hydrogen-bonding close to the superhydrophobic surface. Evidence for capillary evaporation next to the superhydrophobic surface was also found, and this results in very long-range capillary attraction between one superhydrophobic surface and a hydrophobic colloidal probe as shown by AFM colloidal probe force measurements. Addition of a surfactant or ethanol suppresses capillary evaporation.

  • 33.
    Chen, Chengdong
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Hou, Ruiqing
    Zhang, Fan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Dong, Shigang
    Claesson, Per Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Lin, Changjian
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Heating-Induced Enhancement of Corrosion Protection of Carbon Steel by a Nanocomposite Film Containing Mussel Adhesive Protein2017In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 164, no 4, p. C188-C193Article in journal (Refereed)
    Abstract [en]

    Application of protective coatings on metals may involve a thermal treatment process. In this study, the effect of thermal treatment up to 200 degrees C on the corrosion protection was investigated for nanocomposite films composed of mussel adhesive protein (MAP), CeO2 nanoparticles and Na2HPO4 deposited on carbon steel. The morphology and microstructure of the pre-formed nanocomposite film were characterized by scanning electron microscopy/energy dispersive spectroscopy and atomic force microscopy (AFM). The changes in the chemical structure of the nanocomposite film due to the thermal treatment were investigated by infrared reflection absorption spectroscopy. The corrosion protection of the unheated and heated nanocomposite films on carbon steel was evaluated by electrochemical impedance spectroscopy and details of the corrosion process were elucidated by in-situ AFM measurements in 0.1 M NaCl solution. The results show a certain increase in the corrosion protection with time of the nanocomposite film for carbon steel. The analyses reveal that thermal treatment leads to a reduction of water molecules in the nanocomposite film, and an enhanced cross-linking and cohesion of the film due to oxidation of catechols to o-quinones. As a result, the film becomes more compact and gives improved corrosion protection for carbon steel.

  • 34. Chernyy, Sergey
    et al.
    Järn, Mikael
    Shimizu, Kyoko
    Swerin, Agne
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pedersen, Steen Uttrup
    Daasbjerg, Kim
    Makkonen, Lasse
    Claesson, Per
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Iruthayaraj, Joseph
    Superhydrophilic Polyelectrolyte Brush Layers with Imparted Anti-Icing Properties: Effect of Counter ions2014In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 6, no 9, p. 6487-6496Article in journal (Refereed)
    Abstract [en]

    This work demonstrates the feasibility of superhydrophilic polyelectrolyte brush coatings for anti-icing applications. Five different types of ionic and nonionic polymer brush coatings of 25-100 nm thickness were formed on glass substrates using silane chemistry for surface premodification followed by polymerization via the SI-ATRP route. The cationic [2-(methacryloyloxy)ethyl]trimethylammonium chloride] and the anionic [poly(3-sulfopropyl methacrylate), poly(sodium methacrylate)] polyelectrolyte brushes were further exchanged with H+, Li+, Na+, K+, Ag+, Ca2+, La3+, C16N+, F-, Cl-, BF4-, SO42-, and C12SO3- ions. By consecutive measurements of the strength of ice adhesion toward ion-incorporated polymer brushes on glass it was found that Li+ ions reduce ice adhesion by 40% at 18 degrees C and 70% at 10 degrees C. Ag+ ions reduce ice adhesion by 80% at -10 degrees C relative to unmodified glass. In general, superhydrophilic polyelectrolyte brushes exhibit better anti-icing property at -10 degrees C compared to partially hydrophobic brushes such as poly(methyl methacrylate) and surfactant exchanged polyelectrolyte brushes. The data are interpreted using the concept of a quasi liquid layer (QLL) that is enhanced in the presence of highly hydrated ions at the interface. It is suggested that the ability of ions to coordinate water is directly related to the efficiency of a given anti-icing coating based on the polyelectrolyte brush concept.

  • 35. Christenson, H. K.
    et al.
    Claesson, Per M.
    KTH, Superseded Departments, Chemistry.
    Direct measurements of the force between hydrophobic surfaces in water2001In: Advances in Colloid and Interface Science, ISSN 0001-8686, E-ISSN 1873-3727, Vol. 91, no 3, p. 391-436Article, review/survey (Refereed)
    Abstract [en]

    Direct measurements of the force between hydrophobic surfaces across aqueous solutions are reviewed. The results are presented according to the method of preparation of the hydrophobic surfaces. No single model appears to fit all published results, and an attempt is made to classify the measured interactions in three different categories. The large variation of the measured interaction, often within each class, depending on the type of hydrophobic surface is emphasized. (I) Stable hydrophobic surfaces show only a comparatively short-range interaction, although little quantitative data on this attraction have been published. (II) Many results showing very long-range attractive forces are most likely due to the presence of sub-microscopic bubbles on the hydrophobic surfaces. Such an interaction is typically measured between silica surfaces made hydrophobic by silylation. Between self-assembled thiol layers on gold surfaces very short-range attractive forces are possibly due to the presence or nucleation of bubbles. The reason for the apparent stability of these bubbles is not clear and warrants further investigation. (III) Results obtained with LB films of surfactants or lipids on mica appear to give rise to a different type of force that fits neither of these two categories. This force is an exponentially decaying attraction, often of considerable range. The force turns more attractive at smaller separations, and may at short range be similar to the interaction measured between stable hydrophobic surfaces. An apparently similar, exponential attraction is also found between mica surfaces bearing surfactants adsorbed from cyclohexane, between silylated, plasma-treated mica surfaces and between both mica and silica surfaces with surfactants adsorbed in situ. This type of force also occurs between some surfaces of relatively low hydrophobicity as well as between one such hydrophobic surface and a hydrophilic surface. No convincing model can explain this third type of interaction for all systems in which it has been observed. This review of work to date points to the importance of the morphology and structure of the hydrophobic surface, and how it may change during the interaction of two surfaces.

  • 36.
    Claesson, P. M.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry (closed 20081231).
    Dedinaite, A.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry (closed 20081231).
    Mészáros, R.
    Varga, I.
    Association between Polyelectrolytes and Oppositely Charged Surfactants in Bulk and at Solid/Liquid Interfaces2010In: Colloids and Interface Science Series, Wiley-Blackwell, 2010, Vol. 3, p. 337-395Chapter in book (Other academic)
    Abstract [en]

    Mixtures of polyelectrolytes and oppositely charged surfactants find applications in many processes and products that are used in our daily life. Such systems also show many interesting features from a scientific point of view. Due to the combined technological relevance and scientific challenge, considerable research efforts have been made in this area in recent years. This has resulted in new theoretical approaches, the development of simulation methods and new experimental techniques and, of course, a large body of new findings. Together, these efforts have increased the understanding significantly, especially during the last 5 years. This chapter reviews some aspects of this topic, focusing on bulk association and association at solid/liquid interfaces. The review is focused on developments during the 21st century, even though in some cases a historical perspective is also offered.

  • 37.
    Claesson, Per
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Dédinaité, Andra
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Meszaros, R.
    Varga, Imre
    Association between Polyelectrolytes and Oppositely Charged Surfactants in Bulk and at Solid/Liquid Interfaces2007In: Colloid Stability and Application in Pharmacy: Volume 3, Weinheim: Wiley-VCH Verlagsgesellschaft, 2007, p. 337-395Chapter in book (Other academic)
    Abstract [en]

    Mixtures of polyelectrolytes and oppositely charged surfactants find applications in many processes and products that are used in our daily life. Such systems also show many interesting features from a scientific point of view. Due to the combined technological relevance and scientific challenge, considerable research efforts have been made in this area in recent years. This has resulted in new theoretical approaches, the development of simulation methods and new experimental techniques and, of course, a large body of new findings. Together, these efforts have increased the understanding significantly, especially during the last 5 years. This chapter reviews some aspects of this topic, focusing on bulk association and association at solid/liquid interfaces. The review is focused on developments during the 21st century, even though in some cases a historical perspective is also offered.

  • 38.
    Claesson, Per M.
    et al.
    KTH, Superseded Departments, Chemistry.
    Bergström, Lars Magnus
    KTH, Superseded Departments, Chemistry.
    Dedinaite, Andra
    KTH, Superseded Departments, Chemistry.
    Kjellin, M.
    Legrand, J. F.
    Grillo, I.
    Mixtures of cationic polyelectrolyte and anionic surfactant studied with small-angle neutron scattering2000In: Journal of Physical Chemistry B, ISSN 1089-5647, Vol. 104, no 49, p. 11689-11694Article in journal (Refereed)
    Abstract [en]

    Small-angle neutron scattering (SANS) data for solutions containing a highly charged cationic polyelectrolyte and an anionic surfactant are presented. The scattering data were obtained in pure D2O, emphasizing the scattering from the polyelectrolyte, and in a H2O/D2O mixture that contrast matches the polyelectrolyte. In the absence of surfactant, a broad scattering peak due to the mesh size of the polyelectrolyte solution is the most characteristic feature. This peak moves to larger q-values (smaller distances) as the polyelectrolyte concentration is increased, as expected for a semidilute polyelectrolyte solution. Addition of a small amount of surfactant reduces and finally removes this peak. Instead a sharp diffraction peak appears at high q-values. This Bragg peak corresponds to a characteristic distance of 37-39 Angstrom, and it is observed when either the polyelectrolyte or the surfactant is contrast matched by the solvent. Once this peak has appeared, its position does not change when the surfactant concentration is increased. The intensity of the peak grows, however, until a stoichiometric polyelectrolyte-surfactant complex has been formed. The Bragg peak remains in excess surfactant solution. These results are discussed in relation to the structure of the polyelectrolyte-surfactant aggregates and in connection with recent results from surface force and turbidity measurements using the same polyelectrolyte-surfactant pair.

  • 39.
    Claesson, Per M.
    et al.
    KTH, Superseded Departments, Chemistry.
    Dedinaite, Andra
    KTH, Superseded Departments, Chemistry.
    Rojas, O. J.
    Polyelectrolytes as adhesion modifiers2003In: Advances in Colloid and Interface Science, ISSN 0001-8686, E-ISSN 1873-3727, Vol. 104, p. 53-74Article in journal (Refereed)
    Abstract [en]

    Adsorbed layers of polyelectrolytes have been studied with atomic force microscopy (AFM) and the interferometric surface force apparatus (SFA). Particular emphasis was put on determining the effect of the polyelectrolyte charge density on surface topography, and the effect of the polyelectrolyte coating on the adhesive properties. The AFM was employed to image individual polymer chains at low adsorption densities and to characterize the layer topography and coverage at higher adsorption densities. The adhesive properties between two polyelectrolyte-coated surfaces in air were determined as a function of the number of contacts made at any given spot. The data provide evidence for formation of electrostatic bridges, particularly when highly charged polyelectrolytes are used. Further, material transport between the surfaces is observed when the polyelectrolyte is either highly charged or have a very low charge density. For intermediate charge densities we could not observe any indication of material transfer. The adhesion between one polyelectrolyte-coated surface and one bare surface was initially higher than that between two polyelectrolyte-coated surfaces. However, due to material transfer between the two surfaces the adhesion decreased significantly with the number of times that the surfaces were driven into contact. For the polyelectrolytes of the lowest charge density the results suggest that entanglement effects contribute to the adhesive interaction. The modification of the adhesion by polyelectrolytes in practical systems such as in the case of dry-strength additives to improve paper resistance is also considered.

  • 40.
    Claesson, Per M.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP Technical Research Institute of Sweden.
    Dobryden, Illia
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Li, Gen
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    He, Yunjuan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Huang, Hui
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Thorén, Per-Anders
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Haviland, David B.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    From force curves to surface nanomechanical properties2017In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 19, no 35, p. 23642-23657Article in journal (Refereed)
    Abstract [en]

    Surface science, which spans the fields of chemistry, physics, biology and materials science, requires information to be obtained on the local properties and property variations across a surface. This has resulted in the development of different scanning probe methods that allow the measurement of local chemical composition and local electrical and mechanical properties. These techniques have led to rapid advancement in fundamental science with applications in areas such as composite materials, corrosion protection and wear resistance. In this perspective article, we focussed on the branch of scanning probe methods that allows the determination of surface nanomechanical properties. We discussed some different AFM-based modes that were used for these measurements and provided illustrative examples of the type of information that could be obtained. We also discussed some of the difficulties encountered during such studies.

  • 41.
    Claesson, Per M.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Kjellin, Mikael
    Rojas, Orlando J.
    Stubenrauch, Cosima
    Short-range interactions between non-ionic surfactant layers2006In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 8, no 47, p. 5501-5514Article, review/survey (Refereed)
    Abstract [en]

    Short-range interactions between surfactant and lipid layers are of great importance in technical applications in complex fluids such as foams, dispersions and emulsions, as well as in the formulation and performance of dispersants, detergents and flocculants. It is also of utmost importance in biological systems where interactions between biomembranes influence a range of processes. The field of short-range interactions has been thoroughly investigated during the past 30 years, following the emergence of a number of techniques to measure interaction forces, Thus, our understanding has increased considerably and it is timely to summarize relevant knowledge accumulated in this area. In this review we focus on the nature of short-range interactions between non-ionic and zwitterionic surfactant and lipid layers exposing their polar groups to the surrounding medium. We discuss the complex interplay of short-range (van der Waals, hydration, steric and other) forces based on recent theoretical and experimental results.

  • 42.
    Claesson, Per M.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Makuska, R.
    Varga, I.
    Meszaros, R.
    Titmuss, S.
    Linse, P.
    Pedersen, J. Skov
    Stubenrauch, Cosima
    Bottle-brush polymers: Adsorption at surfaces and interactions with surfactants2010In: Advances in Colloid and Interface Science, ISSN 0001-8686, E-ISSN 1873-3727, Vol. 155, no 1-2, p. 50-57Article in journal (Refereed)
    Abstract [en]

    Solution and adsorption properties of both charged and uncharged bottle-brush polymers have been investigated. The solution conformation and interactions in solution have been investigated by small-angle scattering techniques. The association of the bottle-brush polymers with anionic surfactants has also been studied. Surfactant binding isotherm measurements, NMR, surface tension measurements, as well as SAXS, SANS and light scattering techniques were utilized for understanding the association behaviour in bulk solutions. The adsorption of the bottle-brush polymers onto oppositely charged surfaces has been explored using a battery of techniques, including reflectometry, ellipsometry, quartz crystal microbalance, and neutron reflectivity. The combination of these techniques allowed determination of adsorbed mass, layer thickness, water content, and structural changes occurring during layer formation. The adsorption onto mica was found to be very different to that on silica, and an explanation for this was sought by employing a lattice mean-field theory. The model was able to reproduce a number of salient experimental features characterizing the adsorption of the bottle-brush polymers over a wide range of compositions, spanning from uncharged bottle-brushes to linear polyelectrolytes. This allowed us to shed light on the importance of electrostatic surface properties and non-electrostatic surface-polymer affinity for the adsorption. The interactions between bottle-brush polymers and anionic surfactants in adsorbed layers have also been elucidated using ellipsometry, neutron reflectivity and surface force measurements.

  • 43.
    Claesson, Per M.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry (closed 20081231).
    Naderi, A.
    Iruthayaraj, J.
    Pettersson, Torbjörn
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry (closed 20081231).
    Vareikis, A.
    Makuska, R.
    Interfacial properties of bottle-brush polyelectrolytes2007In: PROCEEDINGS OF BALTIC POLYMER SYMPOSIUM 2007 / [ed] Makuska, R., Vilnius: VILNIUS UNIV. , 2007, p. 77-81Conference paper (Refereed)
    Abstract [en]

    This article is focused on interfacial properties of bottle brush polyelectrolytes, where side-chains are attached along a polymer backbone. This class of polymer has been much less studied than block copolymers, which is particularly true for bottle brush polyelectrolytes with a high graft density. We have explored how the graft density and charge density of such polymers affect surface properties, as well as some bulk properties. The adsorption of this class of polymer onto negatively charged silica and mica surfaces has been determined. On mica adsorption is driven by electrostatic forces whereas on silica both electrostatic forces and interactions between silica and ethylene oxide chains drive the adsorption. On silica the adsorbed amount is very sensitive to solution ionic strength and pH. We also report on surface interactions and frictional forces obtained between surfaces coated with bottle brush polyelectrolytes.

  • 44.
    Claesson, Per M.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Poptoshev, Evgeni
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Blomberg, Eva
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Dedinaite, Andra
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Polyelectrolyte-mediated surface interactions2005In: Advances in Colloid and Interface Science, ISSN 0001-8686, E-ISSN 1873-3727, Vol. 114, p. 173-187Article, review/survey (Refereed)
    Abstract [en]

    The current understanding of interactions between surfaces coated with polyelectrolytes is reviewed. Experimental data obtained with various surface force techniques are reported and compared with theoretical predictions. The majority of the studies concerned with interactions between polyelectrolyte-coated surfaces deal with polyelectrolytes adsorbed to oppositely charged surfaces, and this is also the main focus of this review. However, we also consider polyelectrolytes adsorbed to uncharged surfaces and to similarly charged surfaces, areas where theoretical predictions are available, but relevant experimental data are mostly lacking. We also devote sections to interactions between polyelectrolyte brush-layers and to interactions due to non-adsorbing polyelectrolytes. Here, a sufficient amount of both theoretical and experimental studies are reported to allow us to comment on the agreement between theory and experiments. A topic of particular interest is the presence of trapped non-equilibrium states that often is encountered in experiments, but difficult to treat theoretically.

  • 45.
    Claesson, Per
    et al.
    KTH, Superseded Departments, Chemistry.
    Poptochev, Evgeni
    KTH, Superseded Departments, Chemistry.
    Blomberg, Eva
    KTH, Superseded Departments, Chemistry.
    Surface Forces and Emulsion Stability2004In: Food Emulsions / [ed] Sjöblom, J., Friberg, S. and Larsson, K., New York: Marcel Dekker, 2004, 4, p. 257-297Chapter in book (Other academic)
  • 46.
    Claesson , Per
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Rutland, Mark W.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Measuring Interactions between Surfaces2001In: Handbook of Applied Surface and Colloid Chemistry, John Wiley and Sons , 2001Chapter in book (Refereed)
  • 47.
    Claesson, Per
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Stubenrausch, C
    Krustev, R
    Johansson, I
    Thin Film and Foam Properties of Sugar-Based Surfactants2009In: Sugar-Based Surfactants: Fundamentals and Applications / [ed] Ruiz, Cristóbal Carnero, Boca Raton: Taylor & Francis Group, 2009, p. 105-152Chapter in book (Other academic)
  • 48.
    Claesson, Per
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    van der Wal, Andreas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Fogden, Andrew
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    New Techniques for Optimization of Particulate Cleaning2007In: Handbook for Cleaning/Decontamination of Surfaces Vol 2 / [ed] I. Johansson, and P. Somasundaran, Amsterdam: Elsevier, 2007, p. 885-927Chapter in book (Other academic)
  • 49.
    Dedinaite, Andra
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Bastardo Zambrano, Luis Alejandro
    Oliveira, C. P.
    Pedersen, J. S.
    Claesson, Per M
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Vareikis, A.
    Makuska, R.
    Solution properties of bottle-brush polyelectrolytes2007In: PROCEEDINGS OF BALTIC POLYMER SYMPOSIUM 2007    , 2007, p. 112-116Conference paper (Refereed)
    Abstract [en]

    Aqueous solution properties of bottle brush polyelectrolytes, where side-chains are attached to a polymer backbone, have been studied. The side chains consist of 45 units long poly(ethylene oxide) groups and the backbone is of the methacrylate type. Small-angle X-ray scattering (SAXS) was used to elucidate the solution conformation of this class of polymer and how it is affected by the side chain density and charge density. The effect of temperature on the solution conformation, and in particular the side chain extension, has also been quantified. At higher concentrations the interactions between the polymer chains in solution affects the scattering, and it is shown that this interaction is well described by a model originally developed for wormlike micelles.

  • 50.
    Dedinaite, Andra
    et al.
    KTH, Superseded Departments, Chemistry.
    Claesson, Per M
    KTH, Superseded Departments, Chemistry.
    Interfacial properties of aggregates formed by cationic polyelectrolyte and anionic surfactant2000In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 16, no 4, p. 1951-1959Article in journal (Refereed)
    Abstract [en]

    Interactions between mica surfaces across aqueous solutions containing mixtures of a highly positively charged polyelectrolyte and an anionic surfactant were studied by use of a surface force apparatus. The investigation was carried out with a constant polyelectrolyte concentration (20 ppm) and a wide range of surfactant concentrations [0-1 times the critical micelle concentration (cmc)]. The chemical composition of the adsorbed polyelectrolyte-surfactant layers was analyzed by x-ray photoelectron spectroscopy (XPS). The properties of polyelectrolyte-surfactant aggregates formed in bulk were studied by measurements of turbidity and electrophoretic mobility. The aggregates formed at low surfactant concentrations (<0.04 times cmc) were positively charged, whereas at higher surfactant concentrations the aggregates carried a net negative charge. It was shown that polyelectrolyte-surfactant aggregates rapidly adsorb on negatively charged mica surfaces regardless of the sign of their charge. At surfactant concentrations up to 0.01 times cmc, the polyelectrolytes adsorb on mica surfaces with loops acid tails stretching out into solution and repulsive steric forces are generated. The thickness of the layer decreases with time and we suggest that this conformational change is accompanied by some expulsion of surfactant from the adsorbed layers. Thick adsorbed layers were formed in the surfactant concentration range 0.02-0.1 times cmc. In this concentration regime the measurement of equilibrium forces was inaccessible due to a very slow layer relaxation. During compression the forces were repulsive and during separation an attraction developed. We attribute this to formation of interlayer surfactant bridges. Finally, at high surfactant concentrations (greater than or equal to 0.4 times cmc) highly negatively charged aggregates adsorb on the surfaces in rather thin layers, resulting in purely repulsive forces of mixed electrostatic and steric origin.

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