Ändra sökning
Avgränsa sökresultatet
2345 201 - 237 av 237
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 201. Stålgren, JJR
    et al.
    Eriksson, J
    YKI – Ytkemiska institutet.
    Boschkova, K
    YKI – Ytkemiska institutet.
    A comparative study of surfactant adsorption on model surfaces using the quartz crystal microbalance and the ellipsometer2002Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 253, s. 190-195Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The nature of hexaethylene glycol mono-n-tetradecyl ether (C14EO6) layers adsorbed onto different model surfaces was systematically investigated by means of QCM-D (quartz crystal microbalance-dissipation) and ellipsometry. The amount of non-ionic surfactant adsorbed is determined both at hydrophilic and hydrophobic surfaces. In particular, the substrates employed were hydrophilic silica, hydrophobized silica (using dimethyldichlorosilane), and hydrophobized gold surfaces (using 10-thiodecane and 16-thiohexadecane). It was shown that the frequency shift obtained from the QCM-D experiments results in an overestimation of the adsorbed mass. This is attributed to two different effects, viz. water that is coupled to the adsorbed layer due to hydration of the polar region of the surfactant and second water that for other reasons is trapped within the adsorbed layer. Furthermore, from the ellipsometry data the adsorbed layer thickness is determined. By combining the thickness information and the dissipation parameter (obtained from the QCM-D experiments), we note that the dissipation parameter is insufficient in describing the viscoelastic character of thin surfactant films

  • 202.
    Summerton, Emily
    et al.
    University of Birmingham, UK.
    Hollamby, Martin J
    University of Keele, UK.
    Zimbitas, Georgina
    University of Birmingham, UK.
    Snow, Tim
    Diamond Light Source, UK.
    Smith, Andrew J
    Diamond Light Source, UK.
    Sommertune, Jens
    RISE - Research Institutes of Sweden, Biovetenskap och material, Yta, process och formulering.
    Bettiol, Jeanluc
    Procter and Gamble Brussels Innovation Center, Belgium.
    Jones, Christopher
    Procter and Gamble Brussels Innovation Center, Belgium.
    Britton, Melanie M
    University of Birmingham, UK.
    Bakalis, Serafim
    University of Birmingham, UK; University of Nottingham, UK.
    The impact of N,N-dimethyldodecylamine N-oxide (DDAO) concentration on the crystallisation of sodium dodecyl sulfate (SDS) systems and the resulting changes to crystal structure, shape and the kinetics of crystal growth.2018Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 527, s. 260-266, artikel-id S0021-9797(18)30579-4Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    HYPOTHESIS: At low temperatures stability issues arise in commercial detergent products when surfactant crystallisation occurs, a process which is not currently well-understood. An understanding of the phase transition can be obtained using a simple binary SDS (sodium dodecyl sulfate) + DDAO (N,N-dimethyldodecylamine N-oxide) aqueous system. It expected that the crystallisation temperature of an SDS system can be lowered with addition of DDAO, thus providing a route to improve detergent stability.

    EXPERIMENTS: Detergent systems are typically comprised of anionic surfactants, non-ionic surfactants and water. This study explores the crystallisation of a three component system consisting of sodium dodecyl sulfate (SDS), N,N-dimethyldodecylamine N-oxide (DDAO), and water using wide-angle X-ray scattering (WAXS), differential scanning calorimetry (DSC) and confocal Raman microscopy.

    FINDINGS: O, formed whereas for mixed SDS + DDAO systems no such structure was detected during crystallisation.

  • 203. Svendsen, IE
    et al.
    Lindh, L
    Elofsson, U
    YKI – Ytkemiska institutet.
    Arnebrant, T
    Studies on the exchange of early pellicle proteins by mucin and whole saliva2008Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 321, nr 1, s. 52-59Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Adsorption of small pellicle proteins statherin or proline-rich protein 1 (PRP1), respectively, and subsequent adsorption of human whole saliva (HWS) or salivary mucin MUC5B, respectively, was studied using ellipsometry and total internal reflectance fluorescence. Differences in elution (using sodium dodecyl sulphate (SDS) solutions) between mixed and single protein films were also investigated. On both hydrophilic and hydrophobized surfaces HWS and MUC5B were found to adsorb to pre-adsorbed layers of statherin and PRP1, respectively. Statherin adsorption on both substrate types showed no or minor exchange by HWS or MUC5B and no change in SDS elution between mixed and single protein films. Small amounts of PRP1 were exchanged by HWS on both surface types and the SDS elutable fractions were similar or larger for mixed films compared to single protein films. PRP1 and MUC5B in sequence showed minor exchange of PRP1 on hydrophilic surfaces, while no exchange could be established on hydrophobized substrates. SDS elutable fractions decreased for PRP1 and MUC5B mixed films compared to single protein films. In conclusion, minor amounts of statherin and PRP1 are exchanged during the time course of the experiments, which indicates that these proteins may to a large extent remain incorporated in the pellicle.

  • 204. Swansson Vethamuthu, M
    et al.
    Almgren, M
    Bergenståhl, B
    YKI – Ytkemiska institutet.
    Mukhtar, E
    The hexagonal phase and cylindrical micelles in the system alkyltrimethylammonium bromide-sodium desoxycholate-water as studied by x-ray diffraction and fluorescence quenching1996Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 178, s. 538-548Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The hexagonal (E) liquid-crystaline phase in mixtures of sodium desoxycholate (NaDOC) with the catiorwic surfactant cetyltrimethylammonium bromide (CTAB) in water has been investigated by small-angle X-ray diffraction and optical polarizing microscopy. Large proportions of the dihydroxy bile salt can be incorporated in the E phase of the detergent and lead to a decreasing average radius from 22 Å for pure CTAB to 19.5 Å at 46 mole% of NaDOC. The introduction of the bile salt in the cylinders thus increases the curvature, whereas the same bile salt induces a transition to rod-like micelles when added to spherical CTAB micelles at low surfactant concentration. The mixed E phase was identified and characterized as a hexagonal mesophase by optical polarizing microscopy. The diffusion-limited fluorescence quenching of excited state pyrene by dimethylbenzophenone was investigated in the cylindrical mixed micelles of the micellar (Ll) phase in the same system. The decay curves were evaluated using a model of excited state deactivation in infinitely long rod-like micelles without exchange of quenchers (Almgren, M., Alsins, J., Mukhtar, E., and van Stam, J., J. Phys. Chem. 92, 4479 (1988)) and gave as results the relative diffusion coefficient of the excUed probe and quencher. The addition of DOC- up to an equimolar concentration decreased the diffusion coefficient substantially, indicating an increased rigidity of the micelle.

  • 205. Tchaliovska, S
    et al.
    Manev, E
    Radoev, B
    Eriksson, JC
    Claesson, PM
    YKI – Ytkemiska institutet.
    Interactions in equilibrium free films of aqueous dodecylammonium chloride solutions1994Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 168, s. 190-197Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The thickness of thin flat foam films formed in a range of aqueous dodecylammonium chloride solutions at pH 5.9 + 0.2 has been determined using a thin film balance. The results are analyzed within the DLVO theory in order to estimate the interfacial potential of the liquid-air interface. As expected, the interfacial potential increases with increasing surfactant concentration. H owever, it was al so found that the in terfacial potentials deduced from the equilibrium film thickness were significantly lower than those obtained by considering the adsorbed amount (obtained by using the Gibbs' adsorption equation) and the pK.-value of dodecylamine at the interface. The interfacial potential at the air-dodecylammonium chloride solution interface was also found to be significantly lower than the corresponding interfacial potential determined using a surface force apparatus for solid hydrophobic surfaces immersed in dodecylammonium chloride solutions. e 1994 A~~ P~, =.

  • 206. Theander, K
    et al.
    Pugh, RJ
    YKI – Ytkemiska institutet.
    Synergism and foaming properties in mixed nonionic/fatty acid soap surfactant systems2003Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 267, s. 9-17Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The synergism and foaming behavior of a mixed surfactant system consisting of a nonionic surfactant (polyethoxylated alkyl ether CnEm) and a fatty acid soap (sodium oleate) were studied. The micellar interaction parameter (the -parameter) was determined from the cmc following the approach of Rubingh's regular solution theory. For both the C12E6/sodium oleate and the C14E6/sodium oleate mixtures, the results indicate a fairly strong attractive interaction (negative -values), which were in agreement with previous data reported for other nonionic/anionic surfactant systems. The characteristics of the foam produced from the surfactants were evaluated using a glass column equipped with a series of electrodes measuring the conductance of the foam, which enabled the water content of the foam to be determined. From these measurements, since the total foam volume was almost the same for all concentrations and surfactants, we compared the amount of liquid in the foam produced under dynamic foaming and the ability of the foam to entrain the liquid after the airflow was switched-off (static foam stability). The amount of liquid in the foam 100 s after the air was switched-off followed the order NaOl > C12E6 > C14E6. Also, the mixtures had the same foam volumes as the pure surfactants at the same concentration. However, both mixtures had higher concentrations of liquid in the foam when the mole fraction of the nonionic surfactant in the mixed surfactant system was greater than about >0.3 in the solution

  • 207. Theander, K
    et al.
    Pugh, RJ
    YKI – Ytkemiska institutet.
    The influence of pH and temperature on the equilibrium and dynamic surface tension of aqueous solutions of sodium oleate2001Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 239, s. 209-216Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    For aqueous solutions of sodium oleate solution, the dynamic surface tension (using the maximum bubble pressure technique) and the equilibrium surface tensions (using the du Noüy ring method) were studied. Experiments were carried out within the pH range 7 to 13 and at temperatures from 20 to 60∞C. From the equilibrium surface tension studies at 25 ∞C, a wide variation in surface activity was found to occur in the premicellar concentration range, depending on pH and oleate concentration and this was explained by the formation of strongly surface active premicellar species. It was also shown that the cmc of the system increased with pH within the pH range 7-12. Dynamic surface tension experiments were carried out from 20 to 60∞C at concentrations beyond the cmc in alkaline solutions, and the adsorption kinetics at the air/solution interface were analysed using established theoretical diffusion models. From this data, the effective diffusion coefficient (Deff) for the oleate species was determined and the presence of an interfacial activation barrier in the diffusion process was confirmed. It was found that the Deff obtained within the temperature range from 40–60∞C at 2-3 mM were in general agreement with previous reported values for the oleate dimer obtained by pulse-gradient FT-NMR. Furthermore, Deff significantly increased with temperature and also increased with concentration at the higher temperature range (> 40 ∞C).

  • 208.
    Theander, K
    et al.
    YKI – Ytkemiska institutet.
    Pugh, RJ
    YKI – Ytkemiska institutet.
    Rutland, MW
    YKI – Ytkemiska institutet.
    Forces and friction between hydrophilic and hydrophobic surfaces: Influence of oleate species2007Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 313, nr 2, s. 735-746Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The atomic force microscope has been used to investigate normal surface forces and lateral friction forces at different concentrations of sodium oleate, a frequently used fatty acid in the deinking process. The measurements have been performed using the colloidal probe technique with bead materials consisting of cellulose and silica. Cellulose was used together with a printing ink alkyd resin and mica, whereas silica was used with a hydrophobised silica wafer. The cellulose - alkyd resin system showed stronger double layer repulsion and the friction was reduced with increasing surfactant concentration. The adhesive interaction disappeared immediately on addition of sodium oleate. The normal surface forces for cellulose-mica indicated no apparent adsorption of the sodium oleate however, the friction coefficient increased on addition of sodium oleate, which we ascribe to some limited adsorption increasing the effective surface roughness. The silica – hydrophobic silica system showed a completely different surface force behaviour at the different concentrations. An attractive hydrophobic interaction was evident since the surfaces jumped into adhesive contact at a longer distance than the van der Waals forces would predict. The strong adhesion was reflected in the friction forces as a nonlinear relationship between load and friction and a large friction response at zero applied load. Indirect evidence of adsorption to the hydrophilic silica surface was also observed in this case, and QCM studies were performed to confirm the adsorption of material to both surfaces

  • 209. Theander, K
    et al.
    Pugh, RJ
    YKI – Ytkemiska institutet.
    Rutland, MW
    YKI – Ytkemiska institutet.
    Friction force measurements relevant to de-inking by means of atomic force microscope2005Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 291, s. 361-368Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the pulping step of the de-inking process, the ink detaches from the fibres due to shear and physical chemical interaction. In order to get a better understanding of the forces involved between cellulose and ink, the atomic force microscope and the colloidal probe technique have been used in the presence of a model chemical dispersant (hexa-ethyleneglycol mono n-dodecyl ether, C12E6). A cellulose bead was used as the colloidal probe and three different lower surfaces have been used, an alkyd resin, mica and a cellulose sphere. The normal and lateral forces have been measured at a range of nonionic concentrations. It was found that the lateral sliding friction forces deceased with increasing surfactant concentration for both the alkyl resin and mica while no differences were observed for the cellulose surface. In addition, only a very small change in normal force could be detected for the alkyd surface as the concentration changed.

  • 210. Um, S-U
    et al.
    Poptoshev, E
    Pugh, RJ
    YKI – Ytkemiska institutet.
    Aqueous solutions of ethyl (hydroxyethyl) cellulose and hydrophobic modified ethyl (hydroxyethyl) cellulose polymer: Dynamic surface tension measurements1997Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 193, s. 41-49Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The dynamic surface tension of aqueos solutions of ethyl (hydroxyethyl) cellulose (EHEC) and hydrophobic modified ethyl (hydroxyethyl) cellulose (HM-EHEC) were determined using the maximum bubble pressure method. Values were monitored over surface lifetimes ranging from 0.15 to 2.5 s (after dead time corrections). In the low concentration range (<100 ppm) HM-EHEC was shown to be more surface active and the presence of salt. (0.1M) was shown to increase the surface activity of both polymer systems. The results were compared to surface tension measurements carried out over longer time scales, determined using the du Nouy ring technique. From these results, isotherms were constructed relating the surface tension to the surface ageing time. Although the results could not be directly correlated to interfacial diffusion models, the isotherms were found to be comparable to previous data reported for lower molecular weight poly(oxyethylene ether) surfactants and a higher molecular weight EHEC polymer determined using the pendant drop technique. Essentially, the isotherms could be divided into distinct regions; induction period, fast fall region where surface coverage occurs fairly rapidly and finally the meso-equilibrium region. From the Gibbs equation, the number of segments of polymer per unit surface area at saturated adsorption levels was calculated over regions of different ageing times and the results were discussed in terms of configuration changes of the polymer at the interface.

  • 211.
    Wakeham, Deborah
    et al.
    KTH Royal Institute of Technology, Sweden.
    Crivoi, Dana G.
    Rovira i Virgili University, Spain.
    Medina, Francesc
    Rovira i Virgili University, Spain.
    Segarra, Anna M.
    Rovira i Virgili University, Spain.
    Rutland, Mark W.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Life Science. KTH Royal Institute of Technology, Sweden.
    In-situ study of substrate - catalyst interactions in a Juliá-Colonna epoxidation using quartz crystal microbalance with dissipation2016Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 469, s. 263-268Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Quartz crystal microbalance with dissipation (QCM-D) analysis of the hexa-l-Leucine (PLL)-catalyzed epoxidation of chalcone gives in-situ experimental evidences which demonstrate that the reaction proceeds mainly via the formation of a PLL-bound hydroperoxide complex followed by the reversible addition of chalcone. The observations offer an alternative rationalization for the viability of the preferred catalytic pathway.

  • 212. Waltermo, Å
    et al.
    Claesson, PM
    YKI – Ytkemiska institutet.
    Johansson, I
    Alkyl glucosides on hydrophobic surfaces studied by surface force and wetting measurements1996Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 183, s. 506-514Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The wetting properties of hydrophobized surfaces in the presence of alkyl glucosides have been studied using a Wilhelmy balance technique, and the interparticle forces acting between such surfaces have been investigated using the interferometric surface force apparatus. The adsorption at concentrations well below the cmc is rather limited both for the anomerically pure octyl b-glucoside and for the technical product based on the branched octyl glucoside, 2-ethylhexyl glucoside. However, the adsorption results in a decreasing surface hydrophobicity, and consequently the force needed to separate two such surfaces from each other is reduced. At the cmc for octyl b-glucoside, a surfactant monolayer is adsorbed on each surface. The interaction between the glucose units gives rise to a short-range repulsive force. Beyond the range of this repulsive force a weak attraction is experienced. Addition of a small amount of octyl a-glucoside does not change the short-range interaction significantly. The technical 2-ethylhexyl glucoside surfactant behaves similarly to the anomerically pure surfactant at low concentrations. The solution with the technical glucoside phase-separates at high surfactant concentration. It is observed that under such conditions a thick layer is deposited on each surface.

  • 213. Waltermo, Å
    et al.
    Sjöberg, M
    Anhede, B
    Claesson, PM
    YKI – Ytkemiska institutet.
    Adsorption of an ethoxylated amine surfactant on mica and its effect on the surface forces1993Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 156, s. 365-376Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The adsorption of tetraoxyethylene dodecylamine (C12NHE4) on mica and its effect on the interparticle forces between negatively charged muscovite mica surfaces has been studied employing the surface force technique. The pH of the solution has a decisive influence on the amount adsorbed, the structure of the adsorbed layer, and the interparticle forces. The main parameters which determine the structure of the adsorbed C12NHE4 -- layer are the area per lattice charge compared to the size of the molecule, the affinity between the polar group and the surface, and the affinity between the polar group and water. Below a pH of about 8 the positively charged ammonium group binds electrostatically and a surfactant monolayer is formed on each surface. At a surfactant concentration of 10-4 M, (a factor of 4 below the cmc) the surfaces are nearly uncharged. The attractive force between the monolayer coated surfaces is of a similar magnitude as the expected van der Waals force. At a pH value of 9-10 the majority of the surfactants are uncharged. Consequently, the head-group repulsion decreases, and, at a surfactant concentration of 10-4 M, an uncharged bilayer builds up on each surface. At short separations a steric force/hydration force arises from compression and dehydration of the polar groups that are directed towards the solution. At even higher pH values the affinity between the polar group and the surface decreases resulting in a disordered adsorbed layer. A repulsive electrostatic double-layer force dominates at large distances, and a steric force/hydration force is present at short surface separations. As the pH is lowered again the outer layer desorbs, which results in a reappearance of a strong attractive force at short separations.

  • 214.
    Walther, Bernhard
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Hamberg, Lars
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Walkenström, Pernilla
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Hermansson, Ann-Marie
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Formation of shaped drops in a fast continuous flow process2004Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 270, nr 1, s. 195-204Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Drop shaping, i.e., flow-induced deformation and fixation by gel formation, was studied under dynamic conditions in a fast continuous process for a water-in-oil system. The system consisted of sunflower oil with different surfactant concentrations (0.1-2% Admul Wol) and a 1.5% ?-carrageenan solution with different Na+ and K+ concentrations. The continuous phase flowed in a 10-mm-wide straight channel into which the dispersed phase was injected via a thin needle. A subsequent shaping channel with a width of 1 or 2 mm deformed the drops. Gel formation was induced by a temperature gradient between the continuous and dispersed phase. Drop sizes in the range 220-roughly 1000 ?m were produced at the needle tip by varying the ratio between the oil and carrageenan flow rate. A diffusion zone before the narrow channel allowed the surfactant to adsorb at the interface. In the elongation flow at the entrance of the shaping geometry, drops underwent initial elongation. In the narrow channel, the drops developed a parabolic shape within a residence time of 0.03-0.15 s. Choosing the correct parameter combinations made it possible to fix the deformation by gel formation within this time period. Shaped drops were shown to be functional. At a concentration of 25% in an emulsion, they increased the viscosity by about 15-20% compared to spherical drops even though 45% of the shaped drops had an aspect ratio of less than 1.2. © 2003 Elsevier Inc. All rights reserved.

  • 215.
    Walther, Bernhard
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Hermansson, Ann-Marie
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Tiemeyer, A.
    Hamberg, Lars
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Fischer, P.
    Windhab, E.J.
    Drop deformation dynamics and gel kinetics in a co-flowing water-in-oil system2005Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 286, nr 1, s. 378-386Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Drop deformation and superimposed gel kinetics were studied in a fast continuous-flow process for a water-in-oil system. Highly monodisperse drops were generated in a double capillary and then deformed passing through a narrowing rectangular channel geometry. Nongelling deformation experiments were used to establish the process and compare it with existing theories. Thereafter, temperature induced drop gelation was included to study its effect on deformation and gel kinetics on short timescales and at high temperature gradients. The disperse phase was a ?-carrageenan solution with additional sodium and potassium ions for gelation experiments. Sunflower oil was used for the continuous phases. Nongelling experiments showed that shear forces are able to deform drops into ellipsoids. A comparison with the small deformation theory by Taylor was surprisingly good even when drop deformation and flow conditions were not in steady state. Superimposed gelation on the deformation process showed clearly the impact of the altered rheological properties of the dispersed and continuous phase. Deformation first increased on cooling the continuous phase until the onset of gel formation, where a pronounced decrease in deformation due to increasing droplet viscosity/viscoelasticity was observed. Drop deformation analyses were then used to detect differences in gelation kinetics at high cooling rate within process times as short as 1.8 s. © 2005 Elsevier Inc. All rights reserved.

  • 216.
    Wang, Min
    et al.
    KTH Royal Institute of Technology, Sweden.
    Zander, Thomas
    Helmholtz Zentrum Geesthacht, Germany.
    Liu, Xiaoyan
    KTH Royal Institute of Technology, Sweden.
    Liu, Chao
    KTH Royal Institute of Technology, Sweden.
    Raj, Akanksha
    KTH Royal Institute of Technology, Sweden.
    Wieland, D. C. Florian
    Helmholtz Zentrum Geesthacht, Germany.
    Garamus, Vasil M.
    Helmholtz Zentrum Geesthacht, Germany.
    Willumeit-Römer, Regine
    Helmholtz Zentrum Geesthacht, Germany.
    Claesson, Per M.
    RISE., SP – Sveriges Tekniska Forskningsinstitut. KTH Royal Institute of Technology, Sweden.
    Dedinaite, Andra
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber. KTH Royal Institute of Technology, Sweden.
    The effect of temperature on supported dipalmitoylphosphatidylcholine (DPPC) bilayers: Structure and lubrication performance2015Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 445, s. 84-92Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Phospholipids fulfill an important role in joint lubrication. They, together with hyaluronan and glycoproteins, are the biolubricants that sustain low friction between cartilage surfaces bathed in synovial fluid. In this work we have investigated how the friction force and load bearing capacity of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayers on silica surfaces are affected by temperature, covering the temperature range 25–52 °C. Friction forces have been determined utilizing the AFM colloidal probe technique, which showed that DPPC bilayers are able to provide low friction forces over the whole temperature interval. However, the load bearing capacity is improved at higher temperatures. We interpret this finding as being a consequence of lower rigidity and higher self-healing capacity of the DPPC bilayer in the liquid disordered state compared to the gel state. The corresponding structure of solid supported DPPC bilayers at the silica–liquid interface has been followed using X-ray reflectivity measurements, which suggests that the DPPC bilayer is in the gel phase at 25 °C and 39 °C and in the liquid disordered state at 55 °C. Well-defined bilayer structures were observed for both phases. The deposited DPPC bilayers were also imaged using AFM PeakForce Tapping mode, and these measurements indicated a less homogeneous layer at temperatures below 37 °C.

  • 217.
    Wedin, P
    et al.
    YKI – Ytkemiska institutet.
    Bergström, L
    Migration and precipitation of soluble species during drying of colloidal films2005Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 281, s. 146-154Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The evaporation-induced convection resulted in a transport of dissolved species, a water-soluble polymer (carboxymethylcellulose) and dissolved CaCO3 , to the drying front of silica and CaCO3 dispersions where the material eventually precipitates. Scanning electron microscopy and chemical analysis showed that the concentration of carboxymethylcellulose, CMC, is highest in the centre of the dried silica film and decreases towards the perifery. The colloidal films of the monodisperse silica particles displayed a high degree of structural order even at high concentrations of the non-adsorbed polymer CMC, which suggests that any depletion induced interparticle attraction is insufficient to affect the assembly of the colloidal crystal. The CaCO3 particles are slightly soluble and we found that rod-like crystals reprecipitated in the centre of the particle films on top of the polyacrylate-coated particles. Addition of CMC disturbs the formation of distinct crystal shapes which was attributed to a complexation of Ca2+ in solution.

  • 218.
    Wedin, P
    et al.
    YKI – Ytkemiska institutet.
    Martinez, CJ
    Lewis, JA
    Daicic, J
    YKI – Ytkemiska institutet.
    Bergström, L
    YKI – Ytkemiska institutet.
    Stress development during drying of calcium carbonate suspensions containing carboxymethylcellulose and latex particles2004Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 272, s. 1-9Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Stress development during drying of coatings produced from aqueous dispersions of calcium carbonate particles in the presence and absence of organic binders was studied using a controlled-environment stress apparatus that simultaneously monitored drying stress, weight loss, and relative humidity. Specifically, the influence of two organic binders on drying stress evolution was investigated: (1) carboxymethylcellulose. a water-soluble viscosifying aid, and (2) a styrene-butadiene latex emulsion of varying glass transition temperature. The stress histories exhibited three distinct regions. First, a period of stress rise was observed, which reflected the capillary tension exerted by the liquid on the particle network. Second, a maximum stress was observed. Third, it was followed by a period of either stress decay or rise depending on the organic species present. Significant differences in stress histories were observed between coatings containing soluble and nonsoluble binders. Maximum drying stresses (sigma(max)) of 0.2-0.5 MPa were observed for coatings produced from pure calcium carbonate or calcium carbonate-latex suspensions. whereas coatings with carboxymethylcellulose exhibited substantially higher sigma(max) values of 1-2 MPa. Upon drying, these coatings were quite hygroscopic, such that cyclic variations in relative humidity induced large cyclic changes in residual stress. Author Keywords:

  • 219. Weissenborn, PK
    et al.
    Pugh, RJ
    YKI – Ytkemiska institutet.
    Surface tension of aqueous solutions of electrolytes : Relationship with ion hydration, oxygen solubility, and bubble coalescence1996Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 184, s. 550-563Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The surface tension of aqueous solutions of simple inorganic electrolytes (36 in total) have been measured by the maximum bubble pressure method as a function of electrolyte concentration up to 1M. In most cases the surface tension increased, however in a minority of cases, certain combinations of cations and anions had a negligible effect or decreased surface tension. Results were analysed in terms of surface tension/electrolyte concentration gradients (d(∆g)/dc) and this parameter was found to correlate with the entropies of ion hydration, Jones-Dole viscosity coefficients and dissolved oxygen gradients. Calculation of Gibbs surface deficiencies for selected electrolytes were carried out using the raw surface tension data. Discussion of the surface tension/electrolyte concentration gradients was extended to the mechanism of inhibition of bubble coalescence by electrolytes. The Gibbs-Marangoni effect did not provide a satisfactory explanation for the inhibition of coalescence for all electrolytes and from the present study we suggest that dissolved gas (microbubble) gradients between macroscopic bubbles plays an important role in the coalescence process. Key words: surface tension; electrolytes; bubble coalescence; dissolved gases.

  • 220.
    Williamson, Nathan H.
    et al.
    University of South Australia, Australia.
    Röding, Magnus
    RISE - Research Institutes of Sweden, Biovetenskap och material, Jordbruk och livsmedel. University College London, Australia.
    Miklavcic, Stanley J.
    University of South Australia, Australia.
    Nydén, Magnus
    RISE - Research Institutes of Sweden, Biovetenskap och material, Jordbruk och livsmedel. University of South Australia, Australia.
    Scaling exponent and dispersity of polymers in solution by diffusion NMR2017Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 493, s. 393-397Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Molecular mass distribution measurements by pulsed gradient spin echo nuclear magnetic resonance (PGSE NMR) spectroscopy currently require prior knowledge of scaling parameters to convert from polymer self-diffusion coefficient to molecular mass. Reversing the problem, we utilize the scaling relation as prior knowledge to uncover the scaling exponent from within the PGSE data. Thus, the scaling exponent—a measure of polymer conformation and solvent quality—and the dispersity (Mw/Mn) are obtainable from one simple PGSE experiment. The method utilizes constraints and parametric distribution models in a two-step fitting routine involving first the mass-weighted signal and second the number-weighted signal. The method is developed using lognormal and gamma distribution models and tested on experimental PGSE attenuation of the terminal methylene signal and on the sum of all methylene signals of polyethylene glycol in D2O. Scaling exponent and dispersity estimates agree with known values in the majority of instances, leading to the potential application of the method to polymers for which characterization is not possible with alternative techniques.

  • 221.
    Wojas, Natalia
    et al.
    RISE - Research Institutes of Sweden, Biovetenskap och material, Yta, process och formulering. KTH Royal Institute of Technology, Sweden.
    Swerin, Agne
    RISE - Research Institutes of Sweden, Biovetenskap och material, Yta, process och formulering. KTH Royal Institute of Technology, Sweden.
    Wallqvist, Viveca
    RISE - Research Institutes of Sweden, Biovetenskap och material, Yta, process och formulering.
    Järn, Mikael
    RISE - Research Institutes of Sweden, Biovetenskap och material, Yta, process och formulering. Omya International AG, Switzerland.
    Schoelkopf, Joachim
    Omya International AG, Switzerland; Aalto University, Finland.
    Gane, Patrick
    Claesson, Per M.
    RISE - Research Institutes of Sweden, Biovetenskap och material, Yta, process och formulering. KTH Royal Institute of Technology, Sweden.
    Iceland spar calcite: Humidity and time effects on surface properties and their reversibility2019Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 541, s. 42-55Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Understanding the complex and dynamic nature of calcite surfaces under ambient conditions is important for optimizing industrial applications. It is essential to identify processes, their reversibility, and the relevant properties of CaCO3 solid-liquid and solid-gas interfaces under different environmental conditions, such as at increased relative humidity (RH). This work elucidates changes in surface properties on freshly cleaved calcite (topography, wettability and surface forces) as a function of time (≤28 h) at controlled humidity (≤3–95 %RH) and temperature (25.5 °C), evaluated with atomic force microscopy (AFM) and contact angle techniques. In the presence of humidity, the wettability decreased, liquid water capillary forces dominated over van der Waals forces, and surface domains, such as hillocks, height about 7.0 Å, and trenches, depth about −3.5 Å, appeared and grew primarily in lateral dimensions. Hillocks demonstrated lower adhesion and higher deformation in AFM experiments. We propose that the growing surface domains were formed by ion dissolution and diffusion followed by formation of hydrated salt of CaCO3. Upon drying, the height of the hillocks decreased by about 50% suggesting their alteration into dehydrated or less hydrated CaCO3. However, the process was not entirely reversible and crystallization of new domains continued at a reduced rate.

  • 222. Wärnheim, T
    et al.
    Bergenståhl, B
    YKI – Ytkemiska institutet.
    Henriksson, U
    Malmvik, A-C
    Nilsson, P
    An X-ray and NMR investigation of the lamellar liquid crystalline phase in the octylamine/octylammonium chloride/water system1987Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 118, s. 233-242Artikel i tidskrift (Refereegranskat)
  • 223.
    Wärnheim, T
    et al.
    YKI – Ytkemiska institutet.
    Henriksson, U
    Effect of cosurfactant structure on surfactant alkyl chain order in lamellar liquid crystals containing sodium n-octanoate1987Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 115, s. 583-586Artikel i tidskrift (Refereegranskat)
  • 224.
    Wärnheim, T
    et al.
    YKI – Ytkemiska institutet.
    Henriksson, U
    The role of the solvent in sodium n-octanoate solutions studied by self-diffusion and nuclear magnetic relaxation measurements1986Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 112, nr 1, s. 66-78Artikel i tidskrift (Refereegranskat)
  • 225.
    Wärnheim, T
    et al.
    YKI – Ytkemiska institutet.
    Jönsson, A
    Phase diagrams of alkyltrimethyl ammonium surfactants in some polar solvents1988Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 125, s. 627-633Artikel i tidskrift (Refereegranskat)
  • 226.
    Wärnheim, T
    et al.
    YKI – Ytkemiska institutet.
    Jönsson, A
    Surfactant aggregation in systems containing alkanol amines and fatty acids1990Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 138, s. 314-323Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The phase diagrams of six different alkanolammonium carboxylate-water systems have been determined. Their phase behavior differs from that of ordinary soaps, since there are large differences between the systems for varying alkyl chain lengths of the carboxylate. In addition, the chemical structure of the alkanolammonium counterion also affects the phase equilibria. For short alkyl chain carboxylates the liquid crystalline phases disappear (e.g., for triethanolammonium octanoate) or decrease in extension (e.g., for monoethanolammonium octanoate), although the surfactant readily aggregates in solution. In contrast, long alkyl chain carboxylates behave like swelling amphiphiles with a low aqueous solubility and the immediate formation of a lamellar phase (e.g., for tri-and monoethanolammonium oleate). It is shown that the distrubition between acid and soap causes these effects. The lower surface charge of the surfactant aggregates compared to that of orinary soap micelles is also reflected in a lowering of the critical micellization concentration.

  • 227.
    Wärnheim, T
    et al.
    YKI – Ytkemiska institutet.
    Sjöberg, M
    Temperature dependent solubilization of hydrocarbon in a nonionic surfactant system with formamide1989Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 131, s. 402-408Artikel i tidskrift (Refereegranskat)
  • 228.
    Wåhlander, Martin
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut. KTH Royal Institute of Technology, Sweden.
    Hansson-Mille, Petra M.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Swerin, Agne
    RISE., SP – Sveriges Tekniska Forskningsinstitut. KTH Royal Institute of Technology, Sweden.
    Superhydrophobicity: Cavity growth and wetting transition2015Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 448, s. 482-491Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We show by using AFM colloidal probe microscopy (combinations of hydrophobic/superhydrophobic as probe/surface) that superhydrophobicity displays a set of specific events when compared with hydrophobicity. Both attraction (due to capillary and wetting forces) and repulsion (most likely due to repelling air/vapor layers or micro-/nanobubbles) occur upon approach and when surfaces are pulled apart both shorter range (50–100 nm or more) and longer range (several micrometers) attractive forces are displayed. The interaction is explained by forces generated through the formation of air and water vaporcavities, in the shorter-range (>50 nm) case maintaining a constant volume of the cavity, in agreement with calculation of capillary forces, and in the longer-range (>1 μm) case through access of air to the cavity, in agreement with thermodynamics of cavity growth. An added sodium dodecyl sulphate surfactant gave a partially reversible wetting transition and reduced the longer-range interaction to shorter-range, suggesting a transfer from the Cassie–Baxter to the Wenzel wetting regime. The findings would be of interest in development of practical applications, such as for anti-soiling, anti-icing, protection of electrical componentsand for extreme water-repellency in paper and textiles.

  • 229. Xhanari, K.
    et al.
    Syverud, Kristin
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Chinga-Carrasco, Gary
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Paso, K.
    Stenius, P.
    Structure of nanofibrillated cellulose layers at the o/w interface2011Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 356Artikel i tidskrift (Refereegranskat)
  • 230. Yaminsky, VV
    et al.
    Claesson, PM
    YKI – Ytkemiska institutet.
    Eriksson, JC
    Wetting hysteresis and instability of hydrophobized glass and mica surfaces1993Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 161, s. 91-100Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Wetting of methylated glass and of Langmuir-Blodgett monolayer coated mica by water and ethanol-water mixtures was investigated by applying the Wilhelmy plate technique. A detailed characterization of the hydrophobized solid surfaces is achieved by a high-resolution continuous record of the wetting tension as a function of the position of the partly immersed plate, the speed of the immersion and retraction, and the time immersed. Among several nonequilibrium and irreversible phenomena studied are (i) static and dynamic wetting tension hysteresis, (ii) wetting tension relaxation and the attainment of equilibrium tension, (iii) desorption and/or reorientation effects at the three-phase contact line and at the solid-liquid interface, and (iv) electrification of solid surfaces on retraction from liquid. The layers produced by dimethyldichlorosilane on glass are stable in both water and ethanol. Dynamic and static wetting tensions are increased, and the equilibrium values are attained at shorter times with increasing alcohol content. The superimposed effect of electrostatic charging also diminishes on the transition from pure water to pure ethanol. Monolayers on mica are generally unstable and undergo degradation both at the three-phase contact line and at the interface with water (similar changes can be traced with composite silane layers on glass before extraction with ethanol). Wetting scanning reveals the changes of wetting tension along the plate arising from the instability of the hydrophobic layer. A rapid desorption of deposited Langmuir-Blodgett layers is observed on immersion in ethanol.

  • 231. Yanez, JA
    et al.
    Laarz, E
    YKI – Ytkemiska institutet.
    Bergström, L
    YKI – Ytkemiska institutet.
    Viscoelastic properties of particle gels1999Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 209, s. 162-172Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of strength of attraction and volume fraction on the mechanical properties of alumina particle networks were investigated. Alumina particle gels were formed reversibly and in situ in the rheometer by cooling alumina particle suspensions with adsorbed poly(12-hydroxy stearic acid) suspended in a marginal solvent, hexanol. The collapse of the polymer layer with decreasing solvency (temperature) induces flocculation when the long-range van der Waals force overcomes the remaining steric repulsion. The gelation temperature depends on volume fraction. At the gel temperature, Tgel, the gel becomes predominantly elastic; at temperatures below Tgel, the elasticity increases with decreasing temperature. We find that the elastic modulus data, measured over a wide range of volume fraction (0.2 < φ < 0.425) and temperature (10-14°C), follows: G = G0(φ - φg)s. This scaling suggests the prefactor and exponent to be independent of temperature. We present some arguments for why subjecting a particle gel to a preshear procedure might result in an temperature-dependent prefactor. By invoking such an effect, we are able to rescale and collapse previously published moduli data on presheared suspensions according to the (φ - φg) expression.

  • 232.
    Zhang, F.
    et al.
    KTH Royal Institute of Technology.
    Sababi, M.
    KTH Royal Institute of Technology.
    Brinck, T.
    KTH Royal Institute of Technology.
    Persson, Dan
    RISE, Swerea, Swerea KIMAB AB.
    Pan, J.
    KTH Royal Institute of Technology.
    Claesson, P.M.
    KTH Royal Institute of Technology.
    In situ investigations of Fe3+ induced complexation of adsorbed Mefp-1 protein film on iron substrate2013Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 404, s. 62-71Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A range of in situ analytical techniques and theoretical calculations were applied to gain insights into the formation and properties of the Mefp-1 film on iron substrate, as well as the protein complexation with Fe3+ ions. Adsorption kinetics of Mefp-1 and the complexation were investigated using QCM-D. The results suggest an initially fast adsorption, with the molecules oriented preferentially parallel to the surface, followed by a structural change within the film leading to molecules extending toward solution. Exposure to a diluted FeCl3 solution results in enhanced complexation within the adsorbed protein film, leading to water removal and film compaction. In situ Peak Force Tapping AFM was employed for determining morphology and nano-mechanical properties of the surface layer. The results, in agreement with the QCM-D observations, demonstrate that addition of Fe3+ induces a transition from an extended and soft protein layer to a denser and stiffer one. Further, in situ ATR-FTIR and Confocal Raman Micro-spectroscopy (CRM) techniques were utilized to monitor compositional/structural changes in the surface layer due to addition of Fe3+ ions. The spectroscopic analyses assisted by DFT calculations provide evidence for formation of tri-Fe3+/catechol complexes in the surface film, which is enhanced by Fe3+ addition. © 2013 The Authors.

  • 233.
    Zhmud, BV
    et al.
    YKI – Ytkemiska institutet.
    Bergström, L
    YKI – Ytkemiska institutet.
    Dissolution kinetics of silicon nitride in aqueous suspension1999Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 218, s. 582-584Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A general system of equations describing the dissolution of polydisperse solids having a porous particulate structure is set up and applied to study the hydrolysis and subsequent dissolution of silicon nitride powder in aqueous suspensions. The latter process has been found to follow a simple kinetic equation, c(t) = cs[1-exp(-kt)], with the dissolution rate constant k = 2.3E-06 1/s and the saturation concentration, cs = 3.2 mmol/l at room temperature and pH9. The role of diffusion is unimportant, so that the concentration of soluble species in pore water changes almost simultaneously with their concentration in the surrounding solution.

  • 234.
    Zhmud, BV
    et al.
    YKI – Ytkemiska institutet.
    Meurk, A
    YKI – Ytkemiska institutet.
    Bergström, L
    YKI – Ytkemiska institutet.
    Evaluation of surface ionization parameters from AFM data1998Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 207, s. 332-343Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new application of atomic force microscopy (AFM) for evaluation of surface ionization parameters on the basis of a charge regulation model is demonstrated. Interactions between symmetrical silicon nitride and silica surfaces have been measured in aqueous electrolytic solutions at different pH and separations from a few Debye lengths down to zero. The obtained experimental data are reported and interpreted on a quantitative level in the framework of Derjaguin's approximation; the computational procedure used for this purpose is outlined. Surface charge density, surface potential, and species concentrations are calculated as functions of pH and separation, unveiling the limits of applicability of classical constant-charge and constant-potential approximations. The integrity of the results on the charge properties of interacting surfaces is discussed in reference to electrokinetic and titration data; potential problems caused by the existence of non-DLVO forces and surface irregularities being highlighted.

  • 235.
    Zhmud, BV
    et al.
    YKI – Ytkemiska institutet.
    Tiberg, F
    YKI – Ytkemiska institutet.
    Hallstensson, K
    YKI – Ytkemiska institutet.
    Dynamics of capillary rise2000Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 228, s. 263-269Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An overview and detailed analysis of the classical theory of capillarity is presented. A number of known equations of capillary rise dynamics are shown to be different limiting cases of one rather general equation. Some internal inconsistencies of the classical equations are pointed out. The role of non-linear dissipation and flow pattern effects in the front zone of the liquid column and near the capillary entrance is discussed. Numerical simulations and experimental data demonstrating some characteristic types of dynamic behavior predicted by the theory are reported. A special attention is paid to the capillary rise of surfactant solutions. As applied to this special case, the existing theory is substantially elaborated by setting up a closed system of equations describing the surfactant transport and relaxation processes in the adsorption layer. A simplified relation for the capillary rise dynamics in the case of strong depletion of the interfacial region is obtained, which is in qualitative agreement with the experimental behavior.

  • 236. Zhou, Ye
    et al.
    Gorochovceva, Natalja
    Makuska, Ricardas
    Dedinaite, Andra
    YKI – Ytkemiska institutet.
    Claesson, Per M
    YKI – Ytkemiska institutet.
    Chitosan-N-poly(ethylene oxide) brush polymers for reduced nonspecific protein adsorption2007Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 305, s. 62-71Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The possibility of using a novel comb polymer consisting of a chitosan backbone with grafted 44 units long poly(ethylene oxide) side chains for reducing nonspecific protein adsorption to gold surfaces functionalized by COOH-terminated thiols has been explored. The comb polymer was attached to the surface in three different ways: by solution adsorption, covalent coupling, and microcontact printing. The protein repellant properties were tested by monitoring the adsorption of bovine serum albumin and fibrinogen employing surface plasmon resonance and imaging null ellipsometry. It was found that a significant reduction in protein adsorption is achieved as the comb polymer layer is sufficiently dense. For solution adsorption this was achieved by adsorption from high pH solutions. On the other hand, the best performance of the microcontact printed surfaces was obtained when the stamp was inked either at low or at high pH. For a given comb polymer layer thickness/poly(ethylene oxide) density, significant differences in protein repellant properties were observed between the different preparation methods, and it is suggested that a reduction in the mobility of the comb polymer layer generated by covalent attachment favors a reduced protein adsorption.

  • 237.
    Österberg, M
    et al.
    YKI – Ytkemiska institutet.
    Laine, J
    Stenius, P
    Kumpulainen, A
    YKI – Ytkemiska institutet.
    Claesson, PM
    YKI – Ytkemiska institutet.
    Forces between xylan-coated surfaces: Effect of polymer charge density and background electrolyte2001Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 242, s. 59-66Artikel i tidskrift (Refereegranskat)
2345 201 - 237 av 237
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
v. 2.35.9