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  • 1.
    Alves, Luis
    et al.
    CQC, University of Coimbra, Portugal.
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. CQC, University of Coimbra, Portugal; Lund University.
    Klotz, Björn
    BASF Personal Care and Nutrition GmbH, Düsseldorf, Germany.
    Böttcher, Axel
    BASF Personal Care and Nutrition GmbH, Düsseldorf, Germany.
    Haake, Hans-Martin
    BASF Personal Care and Nutrition GmbH, Düsseldorf, Germany.
    Antunes, Filipe E.
    CQC, University of Coimbra, Portugal.
    On the rheology of mixed systems of hydrophobically modified polyacrylate microgels and surfactants: Role of the surfactant architecture2018Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 513, s. 489-496Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hypothesis The rheological control of suspensions is of key interest in the formulation design. A chemically cross-linked hydrophobically modified poly(acrylic acid) (HMCL-PAA), used as rheology modifier, is pH sensitive and shows swelling behavior above a critical pH due to the ionization of the acrylic acid groups. At low pH, HMCL-PAA suspensions are liquid and turbid. The binding of surfactants to HMCL-PAA, at low pH conditions, can result in significant changes on rheology and transparency of the polymeric suspensions, due to the swelling of the microgel particles. Experiments The influence of surfactants addition on the rheological properties and transparency of HMCL-PAA suspensions was determined. A systematic study was performed using different types of surfactants (ionic, non-ionic and zwitterionic). Findings The gelation efficiency of HMCL-PAA suspensions at low pH is strongly dependent on surfactant architecture: ionic surfactants are found to be much more efficient than non-ionic or zwitterionic surfactants. Ionic surfactants lead to a liquid-to-gel transition accompanied by an increase of transparency of the suspensions. Among the ionic surfactants, anionics show stronger interactions with the polymer. Also the surfactant hydrophobicity is relevant; the more hydrophobic the surfactant, the stronger is the binding to the polymer and thus the larger the particle swelling. 

  • 2. Carlsson, Håkan
    et al.
    Edlund, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
    Persson, Gerd
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
    Lindström, Birger
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för teknik, fysik och matematik.
    Competition Between Monovalent and Divalent Counterions in a Surfactant / Water System1996Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 180, nr 2, s. 598-604Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Competition between mono- and divalent ions in the association of counterions to the headgroups of amphiphiles was studied in one surfactant system with organic counterions (piperidine+/piperazine2+octanesulfonate) and one with inorganic counterions (Na+/Ca2+octyl sulfate). By conductivity and13C NMR chemical shift measurements the critical micelle concentration (CMC) was found to decrease drastically when small amounts of divalent counterions were present in the system. Self-diffusion coefficients of surfactant ions and organic counterions were measured in the micellar phase by the Fourier transform pulsed-gradient spin-echo (FT-PGSE) NMR method. The degree of counterion binding in the micellar system with piperidine+/piperazine2+counterions was obtained from FT-PGSE NMR measurements. It was observed that the divalent counterions were more strongly bound than the monovalent counterions. The experimental results were compared with theoretical Poisson–Boltzmann calculations. The cell model was used to study the electrostatic effects. Good agreement between electrostatic theory and experiment was observed; however, an attractive force exists between the monovalent piperidine counterions and the micelle, probably because of hydrophobic interactions.

  • 3.
    Cuomo, Francesca
    et al.
    Univ Molise, Dipartimento Agr, Ambiente Alimenti DIAAA, I-86100 Campobasso, Italy.
    Lopez, Francesco
    Univ Molise, Dipartimento Agr, Ambiente Alimenti DIAAA, I-86100 Campobasso, Italy.
    Piludu, Marco
    Univ Cagliari, Dipartimento Sci Biomed, I-09042 Monserrato, CA, Italy.
    Miguel, Maria G.
    Univ Coimbra, Dept Chem, P-3004535 Coimbra, Portugal.
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Lund Univ, Phys Chem, S-22100 Lund, Sweden.
    Ceglie, Andrea
    Univ Molise, Dipartimento Agr, Ambiente Alimenti DIAAA, I-86100 Campobasso, Italy.
    Release of small hydrophilic molecules from polyelectrolyte capsules: Effect of the wall thickness2015Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 447, s. 211-216Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Polymer nanocapsules assembled on cationic liposomes have been built through the layer-by-layer (LbL) technique. Chitosan and alginate, two biocompatible polyelectrolytes, were used to cover the template, where the Rhodamine B was previously loaded. The multishell formed with the alternate deposition of the polyelectrolytes, according to the principles of the LbL assembly, was supposed to change the permeability of the capsule wall. The thickness of the multishell was seen increasing with the number of layers deposited through the observations with the Transmission Electron Microscope. The permeability of the capsules was studied through Rhodamine B release assays. Nanocapsules with seven layers of polyelectrolytes released the dye slowly compared to the capsules with three or five layers. The Ritger-Peppas model was applied to investigate the release mechanisms and a non-Fickian transport behavior was detected regardless of the number of layers. Values of diffusion coefficients of Rhodamine B through the capsule wall were also calculated. (C) 2014 Elsevier Inc. All rights reserved.

  • 4.
    Edlund, Håkan
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Bydén, Malin
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Lindström, Birger
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Khan, Ali
    Phase Equilibria and Structure of the 1-dodecyl Pyridinium Bromide-Dodecane-Water System1998Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 204, nr 2, s. 312-319Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The isothermal ternary phase diagram for the 1-dodecylpyridinium bromide/dodecane/water system was determined at 40°C by 2H NMR and polarizing microscopy methods. Two liquid crystalline phases, a large cubic area and a normal hexagonal phase, and one isotropic normal micellar solution phase were characterized, and their ranges of existence were determined. The micelles were found to be probably small and spherical at lower concentrations of surfactant, and were found to grow at higher concentrations and on addition of oil. The two-phase areas, L1 + H1 and H1 + I, are both very narrow. The comparatively large cubic area, containing 43-63 wt% surfactant and 3-10 wt% dodecane, is probably consistent of more than one structure. SAXS experiments indicate two different structures built of discrete micellar aggregates.

  • 5.
    Edlund, Håkan
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Bydén, Malin
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Lindström, Birger
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Khan, Ali
    Ternary Phase Equilibria of the 1.dodecyl Pyridinium Bromide-Dodecanol-Water System1997Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 196, nr 2, s. 231-240Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The isothermal ternary phase diagram for the 1-dodecylpyridinium bromide (1-DPB)–water–dodecanol system was determined at 40°C, using2H NMR, polarizing microscopy, and SAXS methods. All of the phases were characterized, and their ranges of existence were determined. The surfactant is easy to dissolve in water, yielding a normal micellar solution phase. After the normal micellar phase, on the binary surfactant–water axis, a normal hexagonal liquid crystalline phase is found at higher surfactant concentrations. On addition of dodecanol, four more phases are formed, i.e. a cubic, a lamellar, and a reverse hexagonal phase, followed by a reverse micellar solution phase. The lamellar liquid crystalline phase dominates the ternary phase diagram. The structures of the liquid crystalline phases were further examined using SAXS measurements, and the results are discussed in terms of the critical packing parameter, cpp, and electrostatic forces. The SAXS experiments show a pronounced swelling of the rods in the hexagonal phase, from 28.5 to 33 Å on addition of dodecanol, whereas the cylindrical aqueous core of the reverse hexagonal phase has a diameter of 18–21 Å, depending on sample composition. The average bilayer thickness of the lamellar phase is about 24 Å.

  • 6.
    Gärdlund, Linda
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Wågberg, Lars
    Royal Institute of Technology, Stockholm.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    New insights into the structure of polyelectrolyte complexes2007Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 312, nr 2, s. 237-246Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The formation of polyelectrolyte complexes (PECs) prepared from oppositely charged linear polyelectrolytes (PELs) was studied by static light scattering at various salt concentrations. The PELs used were poly(allylamine hydro chlorid) (PAH) and the two polyanions poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA). Physical characteristics such as radii of gyration and molecular weights as well as water content of the PECs were determined at various molar mixing ratios. In spite of the relatively small difference in chemical structure between PAA and PMAA, fairly large differences in the mentioned parameters were detected. Generally, PECs consisting of PMAA were larger and contained more water. Moreover, by using cryogenic transmission electron microscopy, transmission microscopy and atomic force microscopy, shape and structure of the prepared PECs were investigated both in solution and after drying. The PECs were found to be spherical in solution and the shape was retained after freeze-drying. PECs adsorbed on silica surfaces and dried in air at room-temperature still showed a three-dimensional structure. However, from the relatively low aspect ratios determined, the PECs were found to be significantly collapsed due to interactions with the silica surface during the adsorption and drying processes.

  • 7.
    Karlsson, S.
    et al.
    Department of Physical Chemistry, Åbo Akademi University, Porthaninkatu 3-5, Turku, FI-20500, Finland.
    Friman, R.
    Department of Physical Chemistry, Åbo Akademi University, Porthaninkatu 3-5, Turku, FI-20500, Finland.
    Lindström, Birger
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Backlund, S.
    Department of Physical Chemistry, Åbo Akademi University, Porthaninkatu 3-5, Turku, FI-20500, Finland.
    Self-assembly in the system decanoic acid-butylamine-water2001Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 243, nr 1, s. 241-247Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The phase behavior of alkanoic acid-alkylamine mixtures in water is mainly dictated by a proton transfer from the acid to the amine. For an asymmetric distribution of carbon atoms in the alkyl chains, the result will be an ionic surfactant with an organic counter-ion. In this study the phase diagram at 298.2 K for the ternary system decanoic acid-butylamine-water has been determined. The phase diagram is dominated by a large isotropic solution region. The selfdiffusion, viscosity, and conductivity measurements in the solution phase for an equimolecular ratio between the acid and the amine indicate a continuous transition from aqueous spherical mixed micelles to highly interacting hydrated acid-amine complexes passing through a bicontinuous region. One liquid crystalline lamellar phase, existing at excess acid, has been found. The small angle Xray scattering results indicate that the amine, due to its slightly amphiphilic character, is distributed between water and the bilayer.

  • 8.
    Medronho, B.
    et al.
    University of Algarve, Faro, Portugal.
    Filipe, A.
    University of Algarve, Faro, Portugal.
    Costa, Carolina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Romano, A.
    University of Algarve, Faro, Portugal.
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Edlund, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Microrheology of novel cellulose stabilized oil-in-water emulsions2018Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 531, nr 1 December 2018, s. 225-232Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Diffusing wave spectroscopy (DWS) is a powerful optical technique suitable to investigate turbid samples in a nondestructive and reproducible way, providing information on the static and dynamic properties of the system. This includes the relative displacement of emulsion droplets over time and changes in the viscoelastic properties. Here, novel and promising cellulose-based oil-in-water (O/W) emulsions were prepared and studied, for the first time, by DWS. Cellulose plays the role of a novel eco-friendly emulsifying agent. The hydrolysis time of cellulose was observed to affect the average size of the emulsion droplets and their stability; the longer the hydrolysis time, the more dispersed and stable the emulsions were found to be. Additionally, a good complementarity between the microrheology (DWS) and macrorheology (mechanical rheometer) data was found. Our work suggests that DWS is a highly attractive method to investigate the stability, aging and microrheology properties of cellulose-based emulsions, providing valuable insights on their microstructure. This technique is thus highly appealing for the characterization and design of novel emulsion formulations.

  • 9.
    Persson, Per
    et al.
    Umeå Universitet.
    Nilsson, Nils
    Umeå Universitet.
    Sjöberg, Staffan
    Umeå Universitet.
    Structure and bonding of orthophosphate ions at the iron oxide aqueous interface1996Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 177, nr 1, s. 263-275Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The surface speciation of orthophosphate ions on goethite has been studied as a function of pH, time, total phosphate concentration, and ionic medium by means of diffuse reflectance FTIR spectroscopy. The samples were prepared in accordance with a distribution diagram of surface species as calculated from thermodynamic data. In agreement with the thermodynamic model three dominating surface complexes could be distinguished with IR spectroscopy, and the relative distribution of the species was shown to be primarily a function of pH. The IR characteristics of the individual surface complexes were indicative of molecular symmetries of the PO4unit of C3v, C2v, and C3v, respectively. This was concluded to be incompatible with the bidentate, bridging structural model previously suggested. Instead, the IR data are in good agreement with a monodentate coordination of phosphate to the surfaces, where the three surface complexes only differ in the degree of protonation. A comparison between the adsorption behavior of phosphate on goethite and hematite was also made. Here the importance of the aqueous stability of the adsorbent on the adsorption mechanism was shown.

  • 10. Rundlöf, Mats
    et al.
    Karlsson, M.
    Wågberg, Lars
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Poptoshev, E.
    Rutland, M.
    Claesson, P.
    Application of the JKR method to the measurement of adhesion to Langmuir-Blodgett cellulose surfaces2000Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 230, nr 2, s. 441-447Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The JKR method has been applied for studying adhesion between poly(dimethylsiloxane) (PDMS) caps and Langmuir-Blodgett cellulose surfaces including the substrate, hydrophobized mica, and two flat mineral surfaces, bare mica and glass, The self-adhesion of PDMS caps and oxidized PDMS caps are included as a reference to compare with literature data. The results of the measurements have been compared with previous studies using the surface force apparatus and similar systems. A satisfactory agreement is obtained for simple systems showing no, or very limited, hysteresis between loading and unloading curves, In several cases, however, a large hysteresis is found between loading and unloading curves, with a larger adhesion measured from the pull-off force than from the JKR-curve determined on loading. This is, for instance, the case for PDMS against cellulose. The situation is analogous to that found in wetting studies showing a large hysteresis between advancing and receding contact angles. (C) 2000 Academic Press.

  • 11.
    Volpati, Diogo
    et al.
    University of São Paulo, Brazil.
    Chachaj-Brekiesz, Anna
    Jagiellonian University, Poland.
    Souza, Adriano L.
    University of São Paulo, Brazil.
    Rimoli, Caio Vaz
    University of São Paulo, Brazil.
    Miranda, Paulo B.
    University of São Paulo, Brazil.
    Oliveira, Osvaldo N., Jr.
    University of São Paulo, Brazil.
    Dynarowicz-Latka, Patrycja
    Jagiellonian University, Poland.
    Semifluorinated thiols in Langmuir monolayers: A study by nonlinear and linear vibrational spectroscopies2015Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 460, s. 290-302Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A series of semifluorinated thiols of the general formula CmF2m+1CnH2nSH (abbr. FmHnSH) have been synthesized and characterized in Langmuir monolayers with surface pressure-area isotherms, complemented with polarization-modulated reflection absorption spectroscopy (PM-IRRAS) and sum-frequency generation (SFG) techniques. A comparative analysis was performed for compounds having the same length of fluorinated segment (F-10) and variable length of the hydrogenated part (H-6, H-10, H-12), and having identical hydrogenated segment (H-12) connected to a fluorinated moiety of different lengths (F-6, F-8, F10). For the sake of comparison, an alkanethiol (H18SH) was also examined, and F10H10COOH and F10H10OH molecules were used for helping the assignment of SFG spectra of CH stretches. SFG was applied to investigate the hydrocarbon chain and the terminal CF3 group, while PM-IRRAS was used to probe CF2 groups. The number of gauche defects in the hydrocarbon chain increased with the increasing length of the molecule, either by elongation of the hydrogenated or perflu-orinated part. SFG measurements recorded at three polarization combinations (ppp, ssp, sps) enabled us to estimate the tilt angle of the terminal CF3 group in semifluorinated thiol molecules as ranging from 35 to 45, which is consistent with nearly vertical fluorinated segments. Upon increasing the surface pressure, the fluorinated segment gets slightly more upright, but the hydrocarbon chain tilt increases while keeping the same average number of gauche defects. The extent of disorder in the hydrogenated segment may be controlled by varying the size of the fluorinated segment, and this could be exploited for designing functionalized surfaces with insertion of other molecules in the defect region.

  • 12. Wågberg, Lars
    et al.
    Pettersson, Gunilla
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Notley, Shannon
    Adsorption of bilayers and multilayers of cationic and anionic copolymers of acrylamide on silcon oxide2004Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 274, nr 2, s. 480-488Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Silica surfaces were consecutively treated with copolymers of cationic and anionic polyacrylamides (C-PAM and A-PAM, respectively) and the layer-by-layer build-up was continuously monitored with the aid of stagnation point adsorption reflectometry (SPAR). Four different charge densities of the cationic polymer and one charge density of the anionic polymer were studied. The solid substrate used in the investigation was an oxidized Si wafer, the charge of which was varied by performing the measurements at different pH. Adsorption measurements were performed both in deionized water and with a background electrolyte concentration of 0.01 M NaCl The results show that the adsorption of C-PAM at pH 6 was dominated by electrostatic interactions. However, a significant nonionic contribution to the adsorption of C-PAM on SiO2 was detected-when the results of adsorption measurements conducted in deionized water and in 0.01 M NaCl were compared. At pH 9, the adsorption of C-PAM onto SiO2 was found to be geometrically restricted since the adsorption stoichiometry between the polymer charges and the charges on the surface was less than I irrespective of the charge of the C-PAM. Adsorption of the A-PAM onto the C-PAM covered surface increases as a function of the adsorbed charges in the first layer. Experiments showed that it was possible to form multilayers of polyelectrolytes on the SiO2 surface provided the charge of the C-PAM was high enough. The critical charge of the polyelectrolyte for the formation of multilayers was also dependent on the charge of the substrate; that is, the lower the surface charge the higher the critical charge of the C-PAM. The substrate affected the amount of polyelectrolyte adsorbed up to the fifth layer. For further layers there was almost a stoichiometric relationship between the charges of the polyelectrolytes in consecutive layers. Results from studies of the formed multilayers with a quartz crystal microbalance (QCM-D) indicated that there was a close correlation between energy dissipation into the multilayers and a decrease in the adsorption as detected with SPAR. This in turn indicates that a decrease in the reflectometer signal does not necessarily indicate a decrease in adsorption.

  • 13.
    Zhang, Renyun
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Hummelgård, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Dvorsek, D
    Jozef Stefan Institute, Slovenia and Mo6, Ljubljana, Slovenia.
    Mihailovic, D
    Jozef Stefan Institute, Slovenia and Mo6, Ljubljana, Slovenia.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Mo6S3I6-Au composites: Synthesis, Conductance, and Applications2010Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 348, nr 2, s. 299-302Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A single-step, premixing method was used to directly deposit gold nanoparticles on Mo6S3I6 (MSI) molecular wire bundles. Gold nanoparticles with different sizes and densities were coated on the MSI by changing the concentration of the gold containing salt, HAuCl4. TEM, SEM, and EDX characterization showed deposition of gold nanoparticles on the MSI nanowire surface. The electrical resistance of these MSI-Au composites was more than 100 times lower than that for pure MSI, and was mainly dependent on the density of the deposited gold nanoparticles. Furthermore, we immobilized thiol group-labeled oligonucleotide on the composites and then hybridized with a fully matched sequence. The resistance of the MSI-Au composites increased during the thiol step, while it decreased by hybridizing, due to the conductance difference between single- and double-stranded DNA chains. These results indicate that this new kind of MSI-Au composite could be used as a platform for different applications, including biosensors.

  • 14.
    Zhang, Renyun
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Hummelgård, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Olin, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Large area porous gold films deposited by evaporation-induced colloidal crystal growth2009Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 340, nr 1, s. 58-61Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Films that are nanostructured in two- or three-dimensions, such as porous ones, are made by several methods including templated growth and self-assembly. Here, we report on a new method that is based on evaporation-induced growth of nanoparticle gold films on a water surface. The film growth was done in a similar way to the well-known evaporation-induced colloidal crystal growth method, but in contrast, we did not directly deposit the film on a solid substrate. The films were instead created on top of a water surface. After the growth process, the films were deposited directly on substrates by a simple pick-up procedure. The deposited porous gold films were uniform with a thickness of 100 nm and had a sheet resistance of 100 Ω/sq. There are several advantages with our method, including simplicity of the protocol, large film area, flexibility in the choice of substrate to be coated, and the ability for multilayer coatings. The latter points to opportunities for fabrication of multilayer 3D porous structure, which may have wide applications in sensors and electrochemical determinations.

  • 15. Örtegren, Jonas
    et al.
    Wantke, Klaus-Dieter
    Motschmann, Hubert
    Möhwald, Helmut
    A study of kinetic molecular exchange processes in the medium frequency range by surface SHG on an oscillating bubble2004Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 279, s. 266-276Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The dilatational properties of fluid surfaces and interfaces have been comprehensively investigated in recent years. For example, an im-proved oscillating bubble device provided experimental results that allow for critical testing of established surface models, such as theLucassen/van den Tempel (LvdT) model. The comparison of the LvdT model with the oscillating bubble experiments demonstrates a mis-match between the model parameters. For example, near the CMC or the limit of solubility the calculated parameters of surfactant solutionsbecome unrealistically large. The deviation can be explained by the introduction of more detailed surface models, in particular by the mod-ification of the effective thickness of the surface layer, its internal structure and the molecular exchange processes between these structures.For the verification of such processes an experimental setup was realized which allows for an independent determination of the instanta-neous adsorption state at the surface of an oscillating bubble inside a surfactant solution. The setup utilizes the Second Harmonic Generation(SHG)—effect at the air–solution interface generated by the light of a pulsed LASER. The set-up is described in detail, and the results of afirst experimental series are presented and discussed in this paper. As system, aqueous solutions of the fluortenside F381 were used.

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