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  • 1. Backlund, S
    et al.
    Boström, G
    Nordli, KG
    Wärnheim, T
    YKI – Ytkemiska institutet.
    Partical phase equilibria and partition of alcohol cosurfactants in ionic microemulsions1990In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 82, p. 290-295Article in journal (Refereed)
    Abstract [en]

    The partial phase behaviour of quintinary microemulsions containing water (0.5 m NaCl), sodium dodecylfate, octane and alcohol, where the alcohol is a butanol or pentanol isomer, has been determined. In addition, the partition of the cosurfactant between the phases has been investigated, as well as in detail for the 1-butanol system. The efficiency of the cosurfactant for forming microemulsions is found to exhibit no simple relationship to its solubility properties. In addition, while branched alcohol cosurfactants promote the formation of solution phases at high surfactant contents.

  • 2. Backlund, S
    et al.
    Lundsten, R
    Ruths, M
    Sjöberg, M
    YKI – Ytkemiska institutet.
    Wärnheim, T
    Partial phase behavior of ionic microemulsions stabilized by sodium dodecylsulfate and alcohol cosurfactants1992In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 88, p. 36-41Article in journal (Refereed)
    Abstract [en]

    Ionic microemulsions, stabilized by sodium dodecylsulfate and alcohol cosurfactants, have been characterized with respect to phase behavior, particularly the composition of the different phases in Winsor type I, II and III systems. The system containing brine, octane, sodium dodecylsulfate and 1-butanol shows a regular phase behavior, in conformity with the anticipated behavior, i.e., 2-3-2 phases. The phase transitions with increasing 1-butanol concentration are analogous to those occurring with increasing salinity, when compared with previous investigations. For the system containing brine, cyclohexane, sodium dodecylsulfate and benzyl alcohol, the behavior becomes more complex, even at low surfactant contents. The transitions are 2-3-2-3-2 phases over a wide composition range. The compositions of the phases at equilibrium are discussed in relation to structural considerations, as determined by conductivity and NMR self-diffusion measurements.

  • 3.
    Bergenståhl, B
    et al.
    YKI – Ytkemiska institutet.
    Fontell, K
    YKI – Ytkemiska institutet.
    Phase equilibria in the system soybean lecithin/water1983In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 68, p. 48-52Article in journal (Refereed)
  • 4.
    Bergenståhl, B
    et al.
    YKI – Ytkemiska institutet.
    Jönsson, A
    Sjöblom, J
    Stenius, P
    YKI – Ytkemiska institutet.
    Wärnheim, T
    Phase behaviour of binary and ternary non-aqueous aerosol OT systems1987In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 74, p. 108-112Article in journal (Refereed)
  • 5.
    Bergström, M
    et al.
    YKI – Ytkemiska institutet.
    Eriksson, JC
    YKI – Ytkemiska institutet.
    Synergistic effects in binary surfactant mixtures2004In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 123, p. 16-22Article in journal (Refereed)
    Abstract [en]

    By considering the main contributions to the micellar free energy we have analysed the synergistic effect often seen on the CMC of a binary surfactant mixture. The synergistic effects are due mainly to the entropic free energy contributions related with the surfactant head groups. Several cases have been treated: (i) For a mixture of a monovalent ionic and a non-ionic surfactant in the absence of added salt we obtain, entirely because of electrostatic reasons, a negative deviation from the ideal behaviour corresponding to an interaction parameter β≈-1. Upon adding an inert salt we found that the magnitude of the synergistic effect first increases, reaches a maximum and eventually decreases. (ii) For mixtures of two ionic surfactants with the same charge number but with different hydrocarbon moieties β-values as low as -10 may arise. (iii) For mixtures of an anionic and a cationic surfactant enormous effects are anticipated yielding β≤-20 depending on the CMCs of respective pure surfactant. (iv) Synergistic effects due to different cross-section areas of the head groups are found to be rather small, with 0 > β > -1, provided the difference in head group size is modest but can become more significant when the size difference is larger.

  • 6. Burns, NL
    et al.
    Holmberg, K
    YKI – Ytkemiska institutet.
    Surface charge characterization and protein adsorption at biomaterials surfaces1996In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 100, p. 271-275Article in journal (Refereed)
    Abstract [en]

    In an effort to more fully understand the nature of protein adsorption, and the role adsorbed proteins have in mediating interfacial processes in biomaterial application, effect of surface charge is being explored. For this purpose, a novel electrokinetic technique whereby electroososmosis is measured at flat plates is being used to characterize surfaces with respect to effective surface charge and origin of charge. Protein adsorption is monitored by in situ ellipsometry or by an enzyme linked immunosorbent assay (ELISA). Correlations can then be made between the observed surface properties and biological response to the surface, including bacterial adherence and complement activation of blood proteins. Surfaces studied include a wide variety of radio frequency plasma polymers, and polysiloxane modified surfaces; all of interest as biomaterials. The plasma polymer surfaces are being used as model surfaces to study protein mediated bacterial adherence. Siloxane polymer coatings are being used to interfere with salivary pellicle and plaque formation on teeth, with different patterns in the adherence of oral bacteria observed with different polysiloxanes. In the above systems, patterns in protein adsorption related to surface charge and functionality, as well as other surface properties, can be identified. It appears that surface charge and charging properties are important factors in formation of biofilms.

  • 7.
    Claesson, PM
    YKI – Ytkemiska institutet.
    Experimental evidence for repulsive and attractive forces not accounted forby conventional dlvo theory1987In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 74, p. 48-54Article in journal (Refereed)
  • 8.
    Claesson, PM
    et al.
    YKI – Ytkemiska institutet.
    Cho, DL
    Gölander, CG
    Kiss, E
    Parker, JL
    Functionalized mica surfaces obtained by a cold plasma process1990In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 82, p. 330-336Article in journal (Refereed)
    Abstract [en]

    A surface modification procedure based on the cold plasma technique has been utilized in order to introduce new functional groups onto muscovite mica surfaces. In the first reaction step mica surfaces are exposed to a water vapor plasma. The interaction between mica surfaces and reactive species in the plasma results in information of surface hydroxyl groups. These groups are reactive toward chlorosilanes in the gas phase, which provides a versatile way to obtain mica surfaces with a variety of different surface chemical groups. For instance, poly(ethylene oxide) chains have been covalently attached to mica surfaces.-In a different surface modification route, mica surfaces have been coated with thin plasma polymer layers. Mechanical and surface properties of plasma polymer films depend, of course, on the type of monomer, but also on the condition used during polymerization (e.g., flow rate, pressure and discharge power). The surface force technique has, together with spectroscopic analyses, provided information about how the adhesion force and mechanical strength of different plasma polymers of acrylic acid depend on the polymer structure.

  • 9.
    Claesson, PM
    et al.
    YKI – Ytkemiska institutet.
    Dedinaite, A
    YKI – Ytkemiska institutet.
    Fielden, M
    Kjellin, M
    YKI – Ytkemiska institutet.
    Audebert, R
    Polyelectrolyte-surfactant interactions at interfaces1997In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 106, p. 24-33Article in journal (Refereed)
    Abstract [en]

    Interactions between negatively charged surfaces coated with cationic polyelectrolytes across solutions containing an anionic surfactant, sodium dodecyl sulphate (SDS) have been studied. Polyelectrolytes with charge densities between 100% and 10%, counted per monomer unit, were used. At low ionic strength the polyelectrolytes adsorb in a flat conformation to neutralize the negative mica surface charge. The higher the linear charge density of the polyelectrolyte, the thinner adsorbed layers are obtained. In no case could any desorption be detected when the polyelectrolyte containing solution was replaced with an aqueous polyelectrolyte-free solution. The presence of SDS at concentrations considerably below the critical micellar concentration, cmc, does in all cases result in a recharging and a considerable swelling of the adsorbed layer. This is due to a cooperative association of surfactants in the preadsorbed polyelectrolyte layer. In case of the 100% charged PCMA, the force versus distance profile displays clear oscillations. We interpret these oscillations as being caused by the spatial arrangement of SDS micelles stabilised by the polyelectrolyte. The oscillations in the force curve remain as the SDS concentration is increased to twice the cmc. No similar oscillations in the force distance curve are observed when the surfaces are precoated with less charged polyelectrolytes. In these cases a strong swelling of the polyelectrolyte layer is observed once the surfactant concentration reaches a critical value (well below the cmc).

  • 10.
    Claesson, PM
    et al.
    YKI – Ytkemiska institutet.
    Herder, PC
    Rutland, MW
    YKI – Ytkemiska institutet.
    Waltermo, Å
    Anhede, B
    Amine functionalized surfactants - pH effects on adsorption and interaction1992In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 88, p. 64-73Article in journal (Refereed)
    Abstract [en]

    The interactions between layers of two hydrolyzable surfactants, dodecylamine (DA) and tetraoxyethylene dodecylamine (TEDA), adsorbed on negatively charged muscovite mica have been investigated. It was found that the variation of the interaction and adsorption as a function of pH was similar, but not identical, for the two kinds of surfactants. At a concentration of 10-4 M at low pH (below 8) both types of surfactants adsorb electrostatically to form a monolayer. The resulting surfaces have a hydrophobic character, particularly in the case of dodecylamine. A series of events takes place as the pH is increased. For DA the first event is that uncharged molecules adsorb within the monolayer. This does not occur to any significant degree for TEDA due to steric hindrance within the adsorbed layer. In the next step a bilayer builds up on the surface. The binding of the outer layer is stronger for DA than for TEDA. The DA bilayer becomes uncharged at pH 10.3, and liquid dodecylamine droplets, which phase separate from the bulk solution at this pH-value, precipitate on the surface. At pH-values above 11-12 the affinity between both types of surfactants and the surface decreases significantly, resulting in a less ordered first layer. In addition a strong surface charge develops that prevents multilayer build-up.

  • 11.
    Dahlgren, MAG
    et al.
    YKI – Ytkemiska institutet.
    Claesson, PM
    YKI – Ytkemiska institutet.
    Surface forces between adsorbed polyelectrolytes in salt solution1993In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 93, p. 206-208Article in journal (Refereed)
    Abstract [en]

    Highly charged cationic polyelectrolyte was adsorbed onto mica from 10-4 M KBr and 10-4 M K2SO4 solutions. The results show that the structure of the adsorbed layer and the total amount adsorbed is dependent on the anion valency. Both the layer thickness and the adsorbed amount increase when the salt anion is of higher valency. Desorption over several days into 10-4 M K2SO4 solution was followed. This indicates the adsorbed layer initially overcompensates the mica lattice charge. After some time, the sign of the charge is re-reversed, due to desorption. Adhesion between the adsorbed layers increase during the desorption process. This adhesion is attributed to bridging of entropic origin.

  • 12.
    Dedinaite, A
    et al.
    YKI – Ytkemiska institutet.
    Claesson, PM
    YKI – Ytkemiska institutet.
    Nygren, J
    Iliopoulos, I
    Interactions between surfaces coated with cationic hydrophobically modified polyelectrolyte in the presence and the absence of oppositely charged surfactant2000In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 116, p. 84-94Article in journal (Refereed)
    Abstract [en]

    (1) Department of Chemistry Surface Chemistry Royal Institute of Technology 100 44 Stockholm and Institute for Surface Chemistry, Box 5607, 114 86 Stockholm Sweden (2) Laboratoire de Physico-Chimie Macromoleculaire, UMR-7615, ESPCI CNRS, Universite Pierre et Marie Curie ESPCI, 10 Rue Vauquelin, 75231 Paris Cedex 5, France The association between a cationic hydrophobically modified polyelectrolyte and an anionic surfactant was investigated in bulk solution and at a negatively charged solid surface. The bulk association was followed by measurements of turbidity and electrophoretic mobility. The maximum turbidity of the solution was found to closely coincide with the point of zero electrophoretic mobility of the aggregates. The forces acting between negatively charged mica surfaces across a dilute aqueous solution of the hydrophobically modified polyelectrolyte were monitored using surface force measurements. The presence of hydrophobic side chains on the polyelectrolyte leads to adsorption in an inner rather compact layer and an outer extended layer. After dilution only the inner layer remains adsorbed to the surface. In the next step, sodium dodecyl sulphate (SDS) was added. It was found that the anionic surfactant is incorporated in the adsorbed layer even at very low bulk concentrations. As the surfactant concentration is increased stepwise the layer first swells and relaxes very slowly during compression. At higher SDS concentrations, desorption occurs. The interfacial properties of the hydrophobically modified polyelectrolyte alone and in mixtures with SDS are in many ways strikingly different to those of non-hydrophobically modified polyelectrolytes having a similar linear charge density. This is due to the importance of hydrophobic interactions between the hydrophobic side chains of the polyelectrolyte and between these groups and the nonpolar part of the surfactant

  • 13.
    Dedinaite, A
    et al.
    YKI – Ytkemiska institutet.
    Iruthayara, J
    Gorochovceva, N
    Makuska, R
    Claesson, PM
    YKI – Ytkemiska institutet.
    Interfacial properties of chitosan-PEO graft oligomers: Surface competition with unmodified chitosan oligomers2006In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 132, p. 124-130Article in journal (Refereed)
    Abstract [en]

    Oligomers of chitosan carrying 45 units long poly(ethylene oxide), PEO, chains grafted to the C-6 position of the sugar units were prepared using a novel synthesis route. The graft density was high, close to one poly(ethylene oxide) chain grafted to each sugar unit of the chitosan oligomer but a small fraction of unreacted chitosan remained in the sample. The molecular weight distribution of the sample was determined using GPC. The interfacial properties of the chitosan-PEO graft oligomers were evaluated using X-ray photoelectron spectroscopy and surface force measurements. It was found that the small fraction of unreacted chitosan was significantly enriched at the solid-solution interface on negatively charged muscovite mica surfaces. The interactions between chitosan-PEO oligomer coated surfaces were found to be dominated by the extended PEO chains, and at high coverage the measured forces were consistent with those expected for polymer brushes. Addition of salt up to 10 mM did not result in any significant desorption of preadsorbed oligomer layers.

  • 14.
    Friberg, S
    et al.
    YKI – Ytkemiska institutet.
    Buraczewska, I
    Microemulsions in the water-potassium oleate-benzene system1978In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 63, p. 1-9Article in journal (Refereed)
  • 15.
    Friberg, S
    et al.
    YKI – Ytkemiska institutet.
    Lapczynska, I
    Microemulsions and solubilization by nonionic surfactants1975In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 56, p. 16-20Article in journal (Refereed)
  • 16.
    Holmberg, K
    YKI – Ytkemiska institutet.
    Role of surfactants in water-borne coatings1998In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 109, p. 254-259Article in journal (Refereed)
    Abstract [en]

    The paper discusses the role of surfactants in latex polymerization and in post-emulsification of binders, such as alkyd resins. The advantage of polymerizable surfactants as emulsifier is pointed out. The paper further discusses competitive adsorption between surfactants and between surfactant and associative thickener in paint formulations.

  • 17.
    Holmberg, K
    YKI – Ytkemiska institutet.
    Unsaturated monoethanolamide ethoxylates as paint surfactants1996In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 101, p. 69-74Article in journal (Refereed)
    Abstract [en]

    The paper discusses use of ethoxylated monoethanolamide of highly unsaturated fatty acids for replacement of nonylphenol ethoxylates in coatings. The double bonds in the hydrophobic tail of the ethanolamide ethoxylates impart both bulkiness and polarizability, properties of value with respect to packing at interfaces and interaction with many pigment surfaces. These ethanolamide ethoxylates may also undergo autoxidation. When used as emulsifiers in alkyd emulsions, drying and film properties are improved as compared to formulations based on ethoxylated nonylphenol of the same HLB number. ESCA analysis shows that the polymerizable surfactant migrates to a lesser extent to the film surfaces than does the reference surfactant.

  • 18.
    Holmberg, K
    et al.
    YKI – Ytkemiska institutet.
    Oh, S-G
    Kizling, J
    YKI – Ytkemiska institutet.
    Microemulsions as reaction medium for a substitution reaction1996In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 100, p. 281-285Article in journal (Refereed)
    Abstract [en]

    Synthesis of sodium decyl sulfonate from 1-bromodecane and sodium sulfite was performed in microemulsions based on nonionic surfactant, in liquid crystals and in 2-phase systems with or without a phase transfer agent added. The reactions were fast in both bicontinuous and W/O microemulsion, slower in liquid crystal and very sluggish in 2-phase systems also in the presence of a Q salt or a crown ether. Addition of a small amount of anionic surfactant to the microemulsion systems decreased reaction rate. Addition of cationic surfactant either increased or decreased the reaction rate depending on the choice of counterion.

  • 19.
    Huldén, M
    et al.
    YKI – Ytkemiska institutet.
    Sjöblom, E
    Adsorption of some common surfactants and polymers on TiO2 pigments1990In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 82, p. 28-37Article in journal (Refereed)
    Abstract [en]

    The adsorption of nonylphenol deca (oxyethyleneglycol) monoether (NPE10), sodium dodecyl sulphate (SDS), polyacrylic acid sodium salt (PAA) and ethyl hydroxyethyl cellulose (EHEC) on TiO2-pigment coated with different mineral oxides is reported. The adsorption isotherms are compared with data obtained by electrophoretic mobility measurements. Despite the limitationsinherent in the mobility measurements, we show that this technique can be used to gain adequate information on the adsorption.-Coating of the TiO2-pigment with different mineral oxides has a strong influence on the adsorption. This can be understood from the different acid/base characteristics of the coatings, e.g., TiO2 coated with Al2 O3 or (Al2 O 3 + SiO2) results in a basic and an acidic surface, respectively. SDS, PAA, and EHEC adsorb on the basic pigment, but not on the acidic one. NPE10 does not adsorb on either pigment, nor does it adsorb on pigment stabilized with pre-adsorbed PAA. The competitive adsorption of PAA and EHEC was studied by the consecutive addition of the polymers to the pigment dispersion. The total amount of adsorbed polymer was always larger with two polymers present compared to one single polymer. EHEC does not significantly influence the adsorption of PAA, irrespectively of whether it is adsorbed before or after the PAA. Conversely, 45% of the preadsorbed EHEC desorbs upon the addition of PAA. When EHEC is added to a pigment with pre-adsorbed PAA, the final amount of EHEC on the surface is significantly lower than the amount adsorbed on the bare pigment.

  • 20. Jha, BK
    et al.
    Svensson, M
    Holmberg, K
    YKI – Ytkemiska institutet.
    A titration calorimetry study of a technical grade APG1998In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 110, p. 230-234Article in journal (Refereed)
    Abstract [en]

    This paper reports titration microcalorimetric measurements on micellization of a technical grade alkyl polyglucoside (APG) surfactant. The dilution enthalpy was recorded at three different temperatures and the curves obtained were compared with those of pure B-octyl glucoside. For comparative purposes titration microcalorimetry was also conducted with the conventional nonionic surfactant octa(ethylene glycol)monododecyl ether and with the anionic surfactant sodium dodecylsulfate, SDS. The results indicate that, contrary to the alcohol ethoxylate, both glucoside surfactants undergo micellization without much loss of water of hydration. Compared with the pure octyl glucoside, the technical grade APG exhibited a lower cmc and a less endothermic enthalpy of micellization at room temperature.

  • 21. Kiss, E
    et al.
    Gölander C-G, Eriksson
    YKI – Ytkemiska institutet.
    JC,
    Surface grafting of polyethyleneoxide optimized by means of ESCA1987In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 74, p. 113-119Article in journal (Refereed)
  • 22.
    Kronberg, B
    et al.
    YKI – Ytkemiska institutet.
    Silveston, R
    On the nature and role of water structuring in the adsorption of nonionic surfactants on hydrophobic surfaces1990In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 83, p. 75-83Article in journal (Refereed)
    Abstract [en]

    High pressure liquid chromatography (HPLC) results were used to calculate the temperature dependence of the hydrocarbon-water interaction parameter. The temperaturte dependence has been interpreted in terms of water structuring around the hydrocarbon. The role of water structuring is to enhance the solubility of hydrocarbons in water, which is equivalent to a decrease of the hydrocarbon-water interaction parameter. The poor solubility of hydrocarbons in water is not due to the water structuring, but to other factors such as the large energy required to form a cavity in the water for the hydrocarbon. This is a reflection of the very large cohesive forces in liquid water. These results, together with the temperature dependence of the polyethylene oxide-water interaction parameter, have been used to calculate the temperature dependence of the adsorption of a nonionic surfactant, viz. an ethoxylated nonyl phenol with 20 ethylene oxide units (NP-EO20). It is shown, that water structuring causes, an increased adsorption with temperature. Without water structuring a decreased adsorption is predicted.

  • 23. Liljeblad, JFD
    et al.
    Rutland, MW
    YKI – Ytkemiska institutet.
    Bulone, V
    Johnson, M
    The structure of model membranes studied by vibrational sum frequency spectroscopy2010In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 137, p. 9-12Article in journal (Refereed)
    Abstract [en]

    The structure and order of insoluble Langmuir monolayers consisting of 1,2-distearoyl-sn-glycero-3-phosphatidylcholine (DSPC or 18:0 PC) and the surrounding water molecules have been investigated by vibrational sum frequency spectroscopy (VSFS). At surface pressures of 1, 15, and 57 mN/m corresponding to molecular areas of 53, 50, and 43 Å 2, respectively, the DSPC molecules formed a well ordered film. Both the VSF signal from the methyl stretching vibrations of the lipid and the surrounding water increased with enhanced surface pressure, as a result of the higher surface density and increased order of the system. Water molecules hydrating the polar parts of the headgroup and in close contact to the hydrocarbon groups of the lipid were observed in all three polarization combinations of the laser beams, and distinguished by their different vibrational frequencies.

  • 24. Lindman, B
    et al.
    Mel'nikov, S
    Mel'nikova, Y
    Nylander, T
    Eskilsson, K
    YKI – Ytkemiska institutet.
    Miguel, M
    DNA-lipid systems. An amphiphile self-assembly and polymer-surfactant perspective2002In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 120, p. 52-63Article in journal (Refereed)
    Abstract [en]

    The interaction between DNA and oppositely charged surfactants has been investigated by several techniques, like fluorescence microscopy, electron microscopy, phase diagram determination, and ellipsometry. The phase behaviour is more strongly associative than that in previously studied systems. A precipitate is formed for very low amounts of surfactant and DNA. DNA compaction is a general phenomenon in the presence of multivalent ions and positively charged surfaces; because of the high charge density there are strong attractive ion correlation effects. The interaction between DNA and catanionic mixtures (i.e., mixtures of cationic and anionic surfactants) was also investigated. We observed that DNA compacts and adsorbs onto the surface of positively charged vesicles and that the addition of anionic surfactant can release free DNA back into solution from a compact globular complex between DNA and cationic surfactant. Finally, we investigated DNA interactions with polycations, chitosans with different chain lengths, by fluorescence microscopy, in vivo transfections assays and cryogenic transmission electron microscopy. The general conclusion is that a chitosan effective in promoting compaction is also efficient in transfection

  • 25. Pettersson, T
    et al.
    Feldötö, Z
    Claesson, PM
    YKI – Ytkemiska institutet.
    Dedinaite, A
    YKI – Ytkemiska institutet.
    The effect of salt concentration and cation valency on interactions between mucin-coated hydrophobic surfaces2008In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 134, p. 1-10Article in journal (Refereed)
  • 26.
    Poptoshev, E
    et al.
    YKI – Ytkemiska institutet.
    Carambassis, A
    Österberg, M
    Claesson, PM
    YKI – Ytkemiska institutet.
    Rutland, MW
    YKI – Ytkemiska institutet.
    Comparison of model surfaces for cellulose interactions; elevated pH2000In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 116, p. 79-83Article in journal (Refereed)
    Abstract [en]

    Two different substrates have been used to measure interaction forces between cellulose and between cellulose and glass at normal and high pH. Forces between microspheres of cellulose (r=20-30 µm) have been measured using the colloidal probe atomic force microscopy technique. Interactions between Langmuir-Blodgett cellulose films on a hydrophobised mica substrate and a glass sphere have been determined with the noninterferometric surface force apparatus. Also, the interaction between two identical Langmuir-Blodgett cellulose films determined with the interferometric surface force apparatus is given for comparison. At low pH (5.5-6) the interaction at large separations in both systems is characterised by a double-layer repulsion with an electrosteric contribution dominating the shorter-range regime. At pH 10, the Langmuir-Blodgett cellulose film swells considerably, which generates a long-range steric repulsion. In many cases several inward steps have been observed in the force-distance curves. We attribute this to a sudden partial collapse of the swollen cellulose film. After initial compression of the steric layer (upon consecutive force runs) the long-range interaction is again dominated by a double-layer force. In contrast, measurements between two cellulose spheres have shown no excessive swelling. Only a limited increase (from about 10 nm to about 20 nm per surface) of the range of the electrosteric repulsion has been found at pH 10. The force at longer distances is in good agreement with the Poisson-Boltzmann theory, with the surface potential increasing with pH as expected.

  • 27.
    Pugh, RJ
    et al.
    YKI – Ytkemiska institutet.
    Rutland, MW
    YKI – Ytkemiska institutet.
    Manev, E
    Claesson, PM
    YKI – Ytkemiska institutet.
    A fundamental study of mica flotation in dodecylamine collector1995In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 98, p. 284-287Article in journal (Refereed)
    Abstract [en]

    The batch flotation response of mica in dodecylamine solution was related to foam film experiments where the stability, thickness, and interfacial potentials at the air/dodecylamine solution interface was determined. These results were compared with surface force data (reported in an earlier publication) in which hydrophobic adhesion (pull-off force), adsorbed film thickness, and the interaction between molecularly smooth mica sheets in the amine collector solution was determined. The data covered a range of pH values. Maximum flotation occurred at pH 8 and correlated to a tightly packed hydrophobio collector monolayer giving maximum hydrophobicity to the mica surface. From extended DLVO theory, it was shown that heterocoagulation between the bubble and the mica could only occur providing there was a very long range hydrophobic interaction force to counterbalance the repulsive van der Waals and electrostatic forces.

  • 28. Schönhoff, M
    et al.
    Schwarz, B
    Larsson, A
    YKI – Ytkemiska institutet.
    Kuckling, D
    Dynamics in polymer layers investigated by NMR techniques2002In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 121, p. 80-87Article in journal (Refereed)
    Abstract [en]

    A large number of different NMR methods are of great usefulness in the investigation of molecular mobility in organic bulk systems, while studies at interfaces are rare owing to the low intrinsic sensitivity of NMR methods. This article presents two examples of the application of spin resonance in investigations of polymers at interfaces, employing polymer-coated colloids: Applying 1H liquid-state NMR to monitor segmental mobility, the phase transition of the thermoreversible polymer poly(N-isopropylacrylamide) is investigated in the restricted geometry of an adsorption layer, and furthermore under the influence of charges in a statistical copolymer. The phase transition is substantially broader than in solution and for the charged copolymer, mobile segments remain even above the transition temperature. This is attributed to a comparatively mobile arrangement of the copolymer layer. Owing to the electrostatic repulsion from the surface, the copolymer layer is confined to a configuration with charged loops extending further from the interface. The second example concerns polyelectrolyte multilayers formed by self-assembly of polyanions and polycations onto colloidal particles. The hydration of the layer system is studied using 1H spin-relaxation rates, R2, of water, which are a measure for the immobilisation of water molecules in the multilayers. A linear increase in R2 with the number of layers is found for [poly(sodium 4-styrenesulfate)/poly(diallyl dimethyl ammonium chloride)]N, reflecting a constant increase in the amount of hydration water with the adsorption of each layer. For [poly(sodium 4-styrenesulfate)/poly(allylamine hydrochloride)]N, involving a weak polyelectrolyte, the data show reversible swelling behaviour with respect to the electric potential of the outer layer: A positive surface charge leads to a swelling of the multilayers, while owing to a negative surface charge deswelling occurs

  • 29.
    Silvander, M
    YKI – Ytkemiska institutet.
    Steric stabilization of liposomes – a review2002In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 120, p. 35-40Article in journal (Refereed)
    Abstract [en]

    The performance of two principally different kinds of intended stabilizers is reviewed. Especially any influence of the stabilizers on the liposome properties such as structure, permeability and surface potential is discussed. Poly(ethylene)oxide-poly(propylene)oxide-poly(ethylene)oxide triblock copolymers have not been shown to function satisfactorily as stabilizers in combination with phospholipids. The incorporation of triblock copolymers of different segment length leads to structural breakdown of the liposome structure even at low concentrations. In addition, incorporation of the copolymers results in extensive leakage of encapsulated material. Neither have there been any reports of unambiguous proof of efficient steric repulsion due to the coating by copolymers. In contrast poly(ethylene) glycol lipids (PEG(2000)-PE) efficiently provide a steric barrier to the liposomes. This is however only true if the surface concentration is kept below a rupture limit. An important additional effect is that the permeability of encapsulated hydrophilic cargo is reduced in the presence of PEG-lipids. The most common PEG-lipids contain a carbamate linkage that introduces a negative surface potential at the liposome surface. However, at medium ionic strength similar to physiological conditions the surface potential is small and does not contribute to any great extent to colloidal stabilization.

  • 30. Skagerlind, P
    et al.
    Folmer, B
    YKI – Ytkemiska institutet.
    Jha, BK
    Svensson, M
    Holmberg, K
    YKI – Ytkemiska institutet.
    Lipase-surfactant interactions1998In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 108, p. 47-57Article in journal (Refereed)
    Abstract [en]

    Interactions between different amphiphiles and Rhizomucor miehei lipase were investigated by a variety of techniques. Complex formation in aqueous bulk solution was studied using surface tension measurements. Interactions at the oil-water and the solid-water interfaces were investigated by measuring mobility of emulsion droplets and by ellipsometry, respectively. The results from the different methods were coherent and indicated that cationic surfactants form complex with the lipase over a broad pH range, also below the isoelectric point of the lipase. No such interaction were found for neither anionic or nonionic surfactants. It is postulated that the interaction between cationic surfactants and lipase is due to a combination of electrostatic attraction and hydrohobic interaction and that no such combined interaction occurs with anionic surfactants. The interaction between cationic surfactant and lipase leads to a reduction of reaction rate in lipase-catalyzed hydrolysis of a palm oil. It is also shown that in the same model reaction a normal straight chain alcohol ethoxylate is a substrate for the lipase. An appreciable amount of fatty acid ester of the surfactant is formed as biproduct of the reaction. Branched-tail alcohol ethoxylates are not substrates and appear not to be competitive inhibitors for the enzyme. Likewise, the double-tailed ester surfactant sodium bis(2-ethylexyl)sulfosuccinate (AOT) seems not to interact with the enzyme active site. Thus, anionic and nonionic surfactants with bulky hydrophobic tails are the preferred surfactants for microemulsion-based reactions with Rhizomucor miehei lipase as catalyst.

  • 31. Solans, C
    et al.
    Infante, R
    Azemar, N
    Wärnheim, T
    YKI – Ytkemiska institutet.
    Phase behaviour of cationic lipoaminoacid surfactant systems1989In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 79, p. 70-75Article in journal (Refereed)
    Abstract [en]

    Alkyl esters of long chain basic aminoacids are know as cationic surfactants which have a very good solubility in water; many of them possess antimicrobial properties and are generally considered milder and less irritant than other surfactants. Long chain Nα-acyl-L- α-amino- ω-guanidine alkyl acid derivatives have recently been synthesized. Physico-chemical and antimicrobial studies of these compounds as a function of the alkyl ester or sodium salt (R), the straight chain length of the fatty acid residue (x) and the number of carbons between the ω-guanidine and α-carbxyl group (n) were carried out. Among the different aminoacid surfactant derivatives synthesized, the methyl ester of Nα-lauroyl arginine (LAM) showed higher activity of both surface and antimicrobial properties. In this study, some fundamental studies on LAM phase behavior in binary and multicomponent systems have been undertaken. The phase equilibria has been determined in the binary LAM/water and ternary LAM/water/alkanol systems. Solubilization of nonpolar compounds such as hydrocarbons has also been investigated.

  • 32. Wärnheim, T
    et al.
    Jönsson, A
    YKI – Ytkemiska institutet.
    Phase behaviour of alkanolammonium carboxylates1992In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 88, p. 18-22Article in journal (Refereed)
    Abstract [en]

    Partial binary phase diagrams for thirteen different alkanolammonium carboxylates with water have been determined. The alkanolamines employed were monoethanolamine, triethanolamine and triisopropanol--amine, while the fatty acid has been varied with respect to chain length (C8 - C22) and saturation. The phase diagrams show the features that distinguish them from ordinary soap-water phase diagrams. First, multi-phase regions and miscibility gaps occur at low concentrations of surfactant, in particular for triethanolammonium carboxylates. Secondly, the stability regions of the liquid crystalline phases are different, and in general smaller com--pared to those formed by the corresponding alkali carboxylates. It is suggested that the first feature is due to that alkanolamines are weak bases and thus, that any surfactant aggregate comprises a few percent of unhydrolyzed acid, while the second feature is attributed to the larger size of the counterion compared to alkali ions, which tends to destabilize ordered structures.

  • 33.
    Wärnheim, T
    et al.
    YKI – Ytkemiska institutet.
    Jönsson, A
    Sjöberg, M
    Phase diagrams for cationic surfactants in polar solvent systems1990In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 82, p. 271-279Article in journal (Refereed)
    Abstract [en]

    Phase diagrams are presented for cationic surfactants, and alkyltrimethyl ammonium bromide in polar solvent systems, such as ethylene glycol, formamide, glycerol, and their mixtures with water. Provided that the solvent is sufficiently lipophobic, and that the hydrocarbon moiety of the surfactant is sufficiently large, liquid crystalline phases form according to the normal association pattern for ionic surfactants. In, for example, ethylene glycol, liquid crystals are only formed with surfactants with a longer alkyl chain length than dodecyl.-The formation of didodecyldimethylammonium bromide microemulsions containing polar solvents- mainly formamide, water and their mixtures-and hydrocarbon has been studied. The extension of the solution phase region may decrease, although the mutual miscibility of polar solvent and the hydrocarbon increases. NMR self-diffusion measurements reveal that this is accompanied by a corresponding loss of structure, i.e., a smaller distinction between polar and apolar regions.

  • 34.
    Ödberg, L
    et al.
    YKI – Ytkemiska institutet.
    McBride, G
    YKI – Ytkemiska institutet.
    Magnusson, KE
    Characterization of the surface of cellulosic fibers using aqueous two-phase partitioning1985In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 70, p. 109-112Article in journal (Refereed)
1 - 34 of 34
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