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  • 1. Fazio, Valentina
    et al.
    Örtegren, Jonas
    Koelsch, Patrick
    Andersen, Audree
    Wantke, Dieter
    Möhwald, Helmut
    Motschmann, Hubert
    New insights in static and dynamic properties of soluble monolayers2003In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 5223, p. 38-49Article in journal (Refereed)
    Abstract [en]

    Abstract In this paper we discuss selected equilibrium and dynamic properties of adsorp-tion layers of soluble surfactants. The surface state has been investigated by nonlinearoptical techniques based on second order χ(2)effects which exhibit a high surface specificityand suppress bulk contributions. The surface tension isotherm σ(c) of the homologousseries of n-alkyldimethylphosphine (n =8 − 12) can be described by Frumkin’s equation ofstate which yields the surface interaction parameter, surface coverage and the correspondingarea per molecule A. The comparison of the surface tension σ at a given area per moleculeA reveals a strong alternation within the homologous series. Odd C2n±1 layers show alower surface tension than the adjacent even members C2n of the homologous series. Thiseffect is also present at low surface coverage (A =1.4nm2) and cannot be attributed to adifferences in the chain-packing within a crystalline state. Infrared-Visible Sum-FrequencyGeneration Spectroscopy (SFGS) has been used to monitor the orientation and chain orderwithin the aliphatic tail. SFGS spectra have been recorded for different chain lengths andat different areas per molecule. The analysis of the spectra yields an order parameterG which is proportional to the number of gauche defects within the aliphatic tail. Theodd-even effect in the surface tension turned out to be accompanied by an odd-even effectin the order parameter G. The data suggest that an ordered structure has a bigger impacton the surface tension than an unordered structure. The odd-even effect is also observedin the orientation of the terminating methyl group as retrieved by polarization dependentSFGS measurements. The data shed some light in the relation between molecular andmacroscopic properties. Furthermore surface dilatational viscoelastic properties of afluorinated amphiphile have been measured by a novel version of the oscillating bubble.The oscillating bubble method generates a non-equilibrium state by a harmonic compressionand expansion of the surface layer formed at the tip of a capillary. The surface state ismonitored by Surface Second Harmonic Generation (SHG). This technique is highly surfacespecific and discriminates between monolayer and subsurface coverage. Our set-up allowsto measure the monolayer coverage under dynamic conditions and to relate this to surfacedilatational viscosity and elasticity. For a purely elastic surface layer the prediction of theLucassen van den Temple model (LvdT) are fulfilled.

  • 2. Johansson, Erik
    et al.
    Lundström, Lisa
    Norgren, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Wågberg, Lars
    Adsorption Behavior and Adhesive Properties of Biopolyelectrolyte Multilayers Formed from Cationic and Anionic Starch.2009In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 10, no 7, p. 1768-1776Article in journal (Refereed)
    Abstract [en]

    Cationic starch (D.S. 0.065) and anionic starch (D.S. 0.037) were used to form biopolyelectrolyte multilayers. The influence of the solution concentration of NaCl on the adsorption of starch onto silicon oxide substrates and on the formation of multilayers was investigated using stagnation point adsorption reflectometry (SPAR) and quartz crystal microbalance with dissipation (QCM-D). The wet adhesive properties of the starch multilayers were examined by measuring pull-off forces with the AFM colloidal probe technique. It was shown that polyelectrolyte multilayers (PEM) can be successfully constructed from cationic starch and anionic starch at electrolyte concentrations of 1 mM NaCl and 10 mM NaCl. The water content of the PEMs was approximately 80% at both electrolyte concentrations. However, the thickness of the PEMs formed at 10 mM NaCl was approximately twice the thickness formed at I mM NaCl. The viscoelastic properties of the starch PEMs, modeled as Voigt elements, were dependent on the polyelectrolyte that was adsorbed in the outermost layer. The PEMs appeared to be more rigid when capped by anionic starch than when capped by cationic starch. The wet adhesive pull-off forces increased with layer number and were also dependent oil the polyelectrolyte adsorbed in the outermost layer. Thus, starch PEM treatment has a large potential for increasing the adhesive interaction between solid substrates to levels higher than can be reached by a single layer of cationic starch.

  • 3. Koolen, J. H.
    et al.
    Moulton, Vincent
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Gutman, I.
    Improving the McClelland inequality for total pi-electron energy2000In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 320, no 3-4, p. 213-216Article in journal (Refereed)
    Abstract [en]

    The McClelland inequality, E less than or equal to root 2mn, estimates the total pi-electron energy (E) of a conjugated hydrocarbon by means of the number of carbon atoms (n) and the number of carbon-carbon bonds (m). We now show that in the general case 2m/n + root(n - 1)(2m - 4m(2)/n(2)) is a better (n,m)-type upper bound for E. An even better estimate, 4m/n + root(n - 2)(2m - 8m(2)/n(2)), holds for alternant hydrocarbons. (C) 2000 Elsevier Science B.V. All rights reserved.

  • 4.
    Koptyug, Andrey
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Optical Detection of the Radical-Ion Pair Spectra in Weak Magnetic Fields1987In: Doklady Akademii Nauk, ISSN 0869-5652, Vol. 297, no 6, p. 1414-1418Article in journal (Refereed)
  • 5. Koptyug, Andrey
    Weak Field ESR Spectrometer1988In: Transactions of Siberian Branch of the USSR Academy of Sciences, Vol. 1, p. 121-124Article in journal (Refereed)
  • 6.
    Koptyug, Andrey
    et al.
    Inst. of Chem. Kinetics & Combustion, Acad. of Sci., Novosibirsk, Russia.
    Grishin, Yurij
    S-band magnetron-based accessory for optical detection of ESR spectra of radiation-induced radical-ion pairs1994In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 5, no 4, p. 363-370Article in journal (Refereed)
    Abstract [en]

    In the development of the technique of reaction yield detected magnetic resonance (RYDMR), a novel simple accessory for optical detection of ESR (OD ESR), based on the S-band continuous wave magnetron generator is presented. Basic technical requirements for the RYDMR accessories are discussed. The successful use of an S-band magnetron as a microwave source for RYDMR experiments is reported for the first time. Along with the use of a simple loop-gap resonator it permits the studies of both polar and non-polar samples with good sensitivity and field resolution. With the help of this accessory, OD ESR spectra of some new acceptors, acridin and fluorescein, were detected and some new solvents, poly(ethylene glycol) and paraffin-based high-voltage insulator oil, were successfully utilized.

  • 7.
    Koptyug, Andrey
    et al.
    Institute of Chemical Kinetics and Combustion, Siberian Branch of the USSR Academy of Sciences, Institutskaya str. 3, Novosibirsk, 630090, USSR.
    Saik, Vladimir
    Anisimov, Oleg
    Molin, Yurij
    Spin-locking in concentration-narrowed OD ESR spectra1989In: Chemical Physics, ISSN 0301-0104, E-ISSN 1873-4421, Vol. 138, no 1, p. 173-178Article in journal (Refereed)
    Abstract [en]

    The effect of spin- locking under the action of a resonance rf field of large amplitude has been observed in the optically detected ESR spectra (OD ESR) of radical-ion pairs both in strong and weak magnetic fields. "Hampering" of singlet-tgriplet transitions occurs for concentrations of aromatic acceptors in non polar solutions at room temperature from 10e-4 to 1 M. It is proposed that in spite of strong concentration narrowing OD ESR signals are inhomogeneously broadened. This can be due to neutral molecule- radical-anion aggregate formation.

  • 8.
    Lidenmark, Cecilia
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Pettersson, Torbjörn
    KTH Royal Inst Technol, SE-10044 Stockholm, Sweden.
    Karlsson, Ola. J.
    Lund University, Lund, Sweden.
    Notley, Shannon M.
    Australian National University, Canberra, Australia.
    Edlund, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Norgren, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    The adhesive behavior of extracted Latex polymers towards Silicon oxide and Cellulose2013In: International Journal of Adhesion and Adhesives, ISSN 0143-7496, E-ISSN 1879-0127, Vol. 44, p. 250-258Article in journal (Refereed)
    Abstract [en]

    The objective with this work is to compare the adhesive behavior for latex polymers of different Glass transition Temperatures (Tg) at different length scales and with different contact times. This is accomplished by two techniques: AFM colloidal probe force measurements and JKR-measurements. The aim is to compare the results from these two techniques and relate them to the interaction of the latex polymers towards oxidized silicon wafers and silica/cellulose probes. Theory suggests that altering the short timeframes used in the colloidal probe technique does not affect the ranking of the adhesion for the different polymers, but for the macroscopic JKR-technique it influences the measured work of adhesion. It is therefore important to let the system reach a steady state before assuming complete spreading and adhesion. AFM and JKR measurements showed the same trends where the polymer with lowest content of styrene has the lowest Tg and the highest adhesion, due to the larger polymer chain mobility.

  • 9.
    Lindman, Björn
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Lunds Universitet.
    Medronho, Bruno
    University of Algarve, Faro, Portugal.
    Alves, Luís
    University of Coimbra, Portugal.
    Costa, Carolina
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Edlund, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Norgren, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    The relevance of structural features of cellulose and its interactions to dissolution, regeneration, gelation and plasticization phenomena2017In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 19, no 35, p. 23704-23718Article in journal (Refereed)
    Abstract [en]

    Cellulose is the most abundant polymer and a very important renewable resource. Since cellulose cannot be shaped by melting, a major route for its use for novel materials, new chemical compounds and renewable energy must go via the solution state. Investigations during several decades have led to the identification of several solvents of notably different character. The mechanisms of dissolution in terms of intermolecular interactions have been discussed from early work but, even on fundamental aspects, conflicting and opposite views appear. In view of this, strategies for developing new solvent systems for various applications have remained obscure. There is for example a strong need for using forest products for higher value materials and for environmental and cost reasons to use water-based solvents. Several new water-based solvents have been developed recently but there is no consensus regarding the underlying mechanisms. Here we wish to address the most important mechanisms described in the literature and confront them with experimental observations. A broadened view is helpful for improving the current picture and thus cellulose derivatives and phenomena such as fiber dissolution, swelling, regeneration, plasticization and dispersion are considered. In addition to the matter of hydrogen bonding versus hydrophobic interactions, the role of ionization as well as some applications of new knowledge gained are highlighted.

  • 10. Morozov, V. A.
    et al.
    Antzutkin, Oleg
    Koptyug, Andrey
    Institute of Chemical Kinetics and Combustion, Novosibirsk, USSR.
    Doktorov, A. B.
    Multiquantum resonances in low-field optically detected ESR of radical-ion pairs1991In: Molecular Physics, ISSN 0026-8976, E-ISSN 1362-3028, Vol. 73, no 3, p. 517-540Article in journal (Refereed)
    Abstract [en]

    Multiquantum resonances in low-field optically-detected electron spin resonance (ESR) spectra of radiation-induced radical-ion pairs of aromatic acceptors in liquid and some polymeric solutions have been studied experimentally and theoretically. Corresponding resonances occur in spectra under the action of relatively intense radiofrequency (RF) pumping, when usual signals are inverse due to spin-locking effect. Special experiments have been carried out to prove that such resonances are not caused by the apparatus. The dependencies of resonance shifts and intensities on the radiofrequency field amplitude for various polarizations of the RF field have been studied. The case of pumping with two independent RF generators has also been analysed. A general theory for multiquarium optically detected ESR spectra of radicalion pairs in liquid solutions has been developed, with spin relaxation processes being neglected. The theory has been applied to calculating multiquantum resonance parameters in transverse RF fields (H1 ⊥ H0) of various polarizations. The mechanism of multiquantum resonance spin dynamics of radical pairs (RP) has been analysed in detail. The shapes of OD ESR spectra components have been studied for the Poisson distribution of RP lifetimes. The developed theory shows qualitative agreement with experimental results

  • 11.
    Niga, Petru
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Crown ethers at the aqueous solution–air interface: 1. Assignments and surface spectroscopy2011In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 13, no 17, p. 7930-7938Article in journal (Refereed)
    Abstract [en]

    The surface of aqueous solutions of 4-Nitro Benzo-15-Crown-5 (NB15C5) and Benzo-15-Crown-5 (B15C5) has been studied using the surface sensitive technique vibrational sum frequency spectroscopy (VSFS). The NO, CN, COC and CH vibrational modes of these compounds at the air–water interface as well as OH vibrational modes of the surface water hydrating this compound have been targeted in order to obtain molecular information about arrangement and conformation of the adsorbed crown ether molecules at the air–water interface. The CH2 vibrational modes of crown ethers have been identified and found to be split due to interaction with ether oxygen. The spectra provide evidence for the existence of a protonated crown complex moiety at the surface leading to the appearance of strongly ordered water species. The interfacial water species are influenced by the resulting charged interface and by the strong Zundel polarizability due to tunneling of the proton species between equivalent sites within the crown ring.

  • 12.
    Niga, Petru
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Crown ethers at the aqueous solution–air interface. Part 2. Electrolyte effects, ethylene oxide hydration and temperature behaviour2011In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 13, no 17, p. 7939-7947Article in journal (Refereed)
    Abstract [en]

    Vibrational Sum Frequency Spectroscopy (VSFS) was employed to study adsorbing films of 4-Nitro Benzo-15-Crown-5 (NB15C5) and Benzo-15-Crown-5 (B15C5) at the aqueous solution–air interface. The surface of the solution is strongly influenced by the presence of crown ether species. Changes in the orientation of NB15C5 were monitored as a function of solution concentration, by targeting the ratio of peak intensities of the CN and NO2 vibrational modes. The water of hydration has also been probed as a function of crown concentration, salt concentration, and temperature. The latter study strongly suggests that the surface can be treated as a charged interface, and that the associated ordered water decreases with increasing ionic strength of the bulk solution.

  • 13.
    Norgren, Magnus
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Edlund, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Lignin: Recent advances and emerging applications2014In: Current Opinion in Colloid & Interface Science, ISSN 1359-0294, E-ISSN 1879-0399, Vol. 19, p. 409-416Article, review/survey (Refereed)
    Abstract [en]

    In this paper, we focus on the recent advances on the physical chemistry of lignin. Emerging trends of incorporating lignin in promising future applications such as controlled release, saccharification of lignocelluloses, bioplastics, composites, nanoparticles, adsorbents and dispersants, in electro-chemical applications and carbon fi bers, arealso reviewed. We briefl y describe the complexity of the lignin structure that influences the solution behavior, both as a macromolecule and a col loid, as well as the potential of being a renewable precursor in the development of high-value applications. Special attention is paid on summarizing the present knowledge on lignin colloidalstability and surface chemistry.

  • 14.
    Norgren, Magnus
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Notley, Shannon
    Department of Applied Mathematics, Research School of Physics and Engineering, Australian National University. Canberra 0200 ACT, Australia..
    Adhesion and detachment of single and associated lignin chains studied using force microscopy.Manuscript (preprint) (Other academic)
    Abstract [en]

    The adhesion of single lignin chains to a substrate was studied using single molecule force spectroscopy. Three lignin samples were investigated, one softwood kraft lignin and two dehydrogenation polymerized (DHP) lignin samples based on coniferyl alcohol and coniferyl aldehyde were used. The desorption force from the silicon nitride atomic force microsope tip for the kraft lignin sample was significantly greater than either of the DHP lignin which was the same within experimental error. The higher desorption force was due to the carboxyl group hydrogen bonding interaction with the tip as well as the less compact polymeric layer at the interface. Furthermore, self-association of lignin chains was observed through the determination of the distribution of the extended chain lengths. For both kraft lignin and the coniferyl aldehyde DHP lignin, chains were extended significantly beyond that expected for polymers of that degree of polymerization and molecular weight. The a-carbon on the coniferyl alcohol lignin has a strong intramolecular hydrogen bonding interaction with the adjacent aryl ether which inhibits the possibility for the ether to participate in intermolecular hydrogen bonding with nearby lignin chains. Thus, the self association for kraft lignin and coniferyl aldehyde lignin was suggested to be dominated by intermolecular hydrogen bonding with carboxyl groups and aryl ether functionalities.

  • 15.
    Norgren, Magnus
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Notley, Shannon
    Department of Applied Mathematics, Research School of Physics and Engineering, Australian National University. Canberra 0200 ACT, Australia.
    Surface energy and wettability of spin-coated thin films of lignin isolated from wood.2010In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 26, no 8, p. 5484-5490Article in journal (Refereed)
    Abstract [en]

    The surface energy of lignin films spin-coated onto oxidised silicon wafer has been determined from contact angle measurements of different test liquids with varying polar and dispersive components. Three different lignin raw materials were used, a kraft lignin from softwood along with milled wood lignin from softwood and hardwood. Infrared spectroscopy was used to identify any major functional group differences between the lignin samples. No significant difference in the total solid-vapour surface energy for the different lignin films was observed however the polar component for the kraft lignin was much greater than for either of the milled wood lignin samples consistent with the presence of carboxyl groups. Furthermore, the total surface energy of lignin of 53-56 mJm-2 is of a similar magnitude to cellulose, also found in the wood cell wall however cellulose has a higher polar component leading to a lower contact angle with water and greater wettability than the milled wood lignin. Although lignin is not hydrophobic according to the strictest definition of a water contact angle of greater than 90°, water may only be considered a partially wetting liquid on a lignin surface. This supports the long-held belief that one of the functions of lignin in the wood cell wall is to provide water-proofing to aid in water transport. Furthermore, these results on the solid-vapour surface energy of lignin will provide invaluable insight for many natural and industrial applications including in the design and manufacture of many sustainable products such as paper, fibreboard and polymer composite blends.

  • 16.
    Norgren, Magnus
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Notley, Shannon M.
    Dept. of Applied Matehmatics, Australian National University.
    Lignin: Functional Biomaterial with Potential in Surface Chemistry and Nanoscience2009In: The Nanoscience and Technology of Renewable Biomaterials, Chichester: Blackwell Publishing, 2009, 1, p. 173-205Chapter in book (Other academic)
  • 17.
    Näslund, Lars-Åke
    et al.
    Linkoping Univ, Thin Film Phys Div, Dept Phys Chem & Biol IFM, SE-58183 Linkoping, Sweden.
    Ingason, Arni S.
    Linkoping Univ, Thin Film Phys Div, Dept Phys Chem & Biol IFM, SE-58183 Linkoping, Sweden.
    Holmin, Susanne
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences. Permascand AB, SE-84010 Ljungaverk, Sweden.
    Rosen, Johanna
    Linkoping Univ, Thin Film Phys Div, Dept Phys Chem & Biol IFM, SE-58183 Linkoping, Sweden.
    Formation of RuO(OH)(2) on RuO2-Based Electrodes for Hydrogen Production2014In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 118, no 28, p. 15315-15323Article in journal (Refereed)
    Abstract [en]

    The catalytic and durable electrode coating of ruthenium dioxide (RuO2), applied on nickel (Ni) substrates, is today utilized as electrocatalytic cathodes for hydrogen production, e.g., in the chlor-alkali process and alkaline water electrolysis. The drawback is, however, the sensitivity to reverse currents obtained during power shutdowns, e.g., at maintenance, where the RuO2-based electrodes can be severely damaged unless polarization rectifiers are employed. Through the material characterization techniques X-ray diffraction and X-ray photoelectron spectroscopy, we can now reveal that RuO2 coatings, when exposed to hydrogen evolution at industrially relevant conditions, transforms into ruthenium oxyhydroxide (RuO(OH)(2)). The study further shows that as the hydrogen evolution proceeds the formed RuO(OH)(2) reduces to metallic ruthenium (Ru).

  • 18.
    Näslund, Lars-Åke
    et al.
    Department of Physics, Chemistry, and Biology (IFM), Linköping University,.
    Sánchez-Sánchez, Carlos M.
    Instituto Universitario de Electroquímica, Universidad de Alicante.
    Ingason, Árni S.
    Uppsala universitet Fysiska sektionen Institutionen för fysik och astronomi Materialfysik .
    Bäckström, Joakim
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Herrero, Enrique
    Instituto Universitario de Electroquímica, Universidad de Alicante.
    Rosen, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Holmin, Susanne
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    The Role of TiO2 Doping on RuO2-Coated Electrodes for the Water Oxidation Reaction2013In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 117, no 12, p. 6126-6135Article in journal (Refereed)
    Abstract [en]

    Electrochemical water splitting into H2 and O2 presents a significant and challenging energy loss due to the high overpotential required at the anode. Today, in industrially relevant applications, dimensionally stable anodes (DSA) based on the electrocatalytic active RuO2 are conventionally utilized. To enhance the resistance against corrosion, incorporation of TiO2 in the RuO2-coated electrodes is widely employed. In the present work we have used scanning electrochemical microscopy (SECM) to demonstrate that TiO2-doped RuO2-coated electrodes, in addition to being more durable, also show an electrocatalytic activity that is, on average, 13% higher as compared to the pure RuO2-coated electrodes. We also demonstrate that cracks in the pure RuO2 coating are the most active zones, probably because Ti from the Ti support has diffused into the first applied layer of the RuO2 coating. To reveal the nature of this enhanced activity for water oxidation displayed on TiO2-doped RuO2 electrodes, we have employed X-ray photoelectron spectroscopy (XPS) for material characterization. The results show that the electrocatalytic activity enhancement displayed on the mixed (Ru1−x:Tix)O2 coating is promoted through a charge transfer from the RuO2 to the TiO2, which provides new and more reactive sites designated as activated RuO2δ+.

  • 19.
    Pavinatto, Adriana
    et al.
    University of São Paulo, Brazil.
    Delezuk, Jorge A.M.
    University of São Paulo, Brazil.
    Souza, Adriano L.
    University of São Paulo, Brazil.
    Pavinatto, Felippe J.
    University of São Paulo, Brazil.
    Volpati, Diogo
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences. São Carlos Institute of Physics, University of São Paulo, USP, P.O. Box 369, São Carlos, SP, Brazil .
    Miranda, Paulo B.
    University of São Paulo, Brazil.
    Campana-Filho, Sérgio P.
    University of São Paulo, Brazil.
    Oliveira Jr., Osvaldo N.
    University of São Paulo, Brazil.
    Experimental evidence for the mode of action based on electrostatic and hydrophobic forces to explain interaction between chitosans and phospholipid Langmuir monolayers2016In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 145, p. 201-207Article in journal (Refereed)
    Abstract [en]

    The interaction between chitosans and Langmuir monolayers mimicking cell membranes has been explained with an empirical scheme based on electrostatic and hydrophobic forces, but so far this has been tested only for dimyristoyl phosphatidic acid (DMPA). In this paper, we show that the mode of action in such a scheme is also valid for dipalmitoyl phosphatidyl choline (DPPC) and dipalmitoyl phosphatidyl glycerol (DPPG), whose monolayers were expanded and their compressibility modulus decreased by interacting with chitosans. In general, the effects were stronger for the negatively charged DPPG in comparison to DPPC, and for the low molecular weight chitosan (LMWChi) which was better able to penetrate into the hydrophobic chains than the high molecular weight chitosan (Chi). Penetration into the hydrophobic chains was confirmed with polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS) and sum frequency generation (SFG) spectroscopy. A slight reduction in conformational order of the lipid chains induced by the chitosans was quantitatively estimated by measuring the ratio between the intensities of the methyl (r+) and methylene (d+) peaks in the SFG spectra for DPPG. The ratio decreased from 35.6 for the closely packed DPPG monolayer to 7.0 and 6.6 for monolayers containing Chi and LMWChi, respectively. Since in both cases there was a significant phospholipid monolayer expansion, the incorporation of chitosans led to chitosan-rich and lipid-rich condensed domains, which mantained conformational order for their hydrophobic tails. The stronger effects from LMWChi are ascribed to an easier access to the hydrophobic tails, as corroborated by measuring aggregation in solution with dynamic light scattering, where the hydrodynamic radius for LMWChi was close to half of that for Chi. Taken together, the results presented here confirm that the same mode of action applies to different phospholipids that are important constituents of mammalian (DPPC) and bacterial (DPPG) cell membranes.

  • 20.
    Strand, Anders
    et al.
    Åbo Akademi Finland / Turku.
    Zasadowski, Dariusz
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Norgren, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Willför, Stefan
    Åbo Akademi Finland / Turku.
    Sundberg, Anna
    Åbo Akademi Finland / Turku.
    Selective froth flotation of pitch components from spruce TMP process water2012In: Appita journal, ISSN 1038-6807, Vol. 65, no 4, p. 337-346Article in journal (Refereed)
    Abstract [en]

    Selective removal of dissolved and colloidal pitch components from an unbleached thermomechanical pulp (TMP)

    pressate by addition of a cationic foaming agent, dodecyltrimethylammonium chloride (DoTAC), and subsequent froth

    flotation was assessed. The experiments were conducted with varying pH, temperature, and concentrations of DoTAC

    and calcium. The concentrations of pitch components, lignans, and dissolved polysaccharides were determined

    before and after flotation.

    All pitch components were removed more efficiently by flotation at pH 5 and 3.5 than by flotation at pH 7.6. Resin

    and fatty acids were removed to a higher degree than neutral pitch substances at all the tested pH levels. Most of the

    water-soluble uronic acids and galactoglucomannans stayed in the TMP water after flotation.

    Froth flotation with DoTAC was an effective way of selectively removing colloidal and dissolved pitch. Removal of pitch,

    especially of resin acids, at an early stage should be beneficial to the overall papermaking process.

  • 21.
    Svanedal, Ida
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Fundamental Characterization and Technical Aspects of a Chelating Surfactant2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The purpose of this study was to investigate the fundamental characteristics of a chelating surfactant in terms of solution behaviour, chelation of divalent metal ions, and interaction in mixtures with different foaming agents and divalent metal ion, as well as examining its prospects in some practical applications. Chelating surfactants are functional molecules, with both surface active and chelating properties, which are water soluble and therefore suitable for chelation in many aqueous environments. The dual functionality offers the possibility to recover the chelating surfactant as well as the metals.

    The DTPA (diethylenetriaminepentaacetic acid)-based chelating surfactant 4-C12-DTPA (2-dodecyldiethylenetriaminepentaacetic acid) was synthesized at Mid Sweden University. In the absence of metal ions, all eight donor atoms in the headgroup of 4-C12-DTPA are titrating and the headgroup charge can be tuned from +3 to -5 by altering the pH. The solution properties, studied by surface tension measurements and NMR diffusometry, were consequently found strongly pH dependent. pH measurements of chelating surfactant solutions as a function of concentration was used to extract information regarding the interaction between surfactants in the aggregation process.

    Small differences in the conditional stability constants (log K) between coordination complexes of DTPA and 4-C12-DTPA, determined by competition measurements utilizing electrospray ionization mass spectrometry (ESI-MS), indicated that the hydrocarbon tail only affected the chelating ability of the headgroup to a limited extent. This was further confirmed in hydrogen peroxide bleaching of thermomechanical pulp (TMP) treated with 4-C12-DTPA.

    Interaction parameters for mixed systems of 4-C12-DTPA and different foaming agents were calculated following the approach of Rubingh’s regular solution theory. The mixtures were also examined with addition of divalent metal ions in equimolar ratio to the chelating surfactant. Strong correlation was found between the interaction parameter and the phase transfer efficiency of Ni2+ ions during flotations. Furthermore, a significant difference in log K between different metal complexes with 4-C12-DTPA enabled selective recovery of the metal ion with the highest log K.

    The findings in this study contribute to the understanding of the fundamental characteristics of chelating surfactants, which can be further utilized in practical applications.

  • 22.
    Svanedal, Ida
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Boija, Susanne
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Almesåker, Ann
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Persson, Gerd
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Andersson, Fredrik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Bylund, Dan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Norgren, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Edlund, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Metal Ion Coordination, Conditional Stability Constants and Solution Behavior of Chelating Surfactant Metal Complexes2014In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 30, no 16, p. 4605-4612Article in journal (Refereed)
    Abstract [en]

    Coordination complexes of some divalent metal ions with the DTPA (diethylenetriaminepentaacetic acid)-based chelating surfactant 2-dodecyldiethylenetriaminepentaacetic acid (4-C12-DTPA) have been examined in terms of chelation and solution behavior. The headgroup of 4-C 12-DTPA contains eight donor atoms that can participate in the coordination of a metal ion. Conditional stability constants for five transition metal complexes with 4-C12-DTPA were determined by competition measurements between 4-C12-DTPA and DTPA, using electrospray ionization mass spectrometry (ESI-MS). Small differences in the relative strength between the coordination complexes of DTPA and 4-C12-DTPA indicated that the hydrocarbon tail only affected the chelating ability of the headgroup to a limited extent. The coordination of Cu2+ ions was investigated in particular, using UV-visible spectroscopy. By constructing Job's plots, it was found that 4-C12-DTPA could coordinate up to two Cu2+ ions. Surface tension measurements and NMR diffusometry showed that the coordination of metal ions affected the solution behavior of 4-C 12-DTPA, but there were no specific trends between the studied divalent metal complexes. Generally, the effects of the metal ion coordination could be linked to the neutralization of the headgroup charge of 4-C 12-DTPA, and the resulting reduced electrostatic repulsions between adjacent surfactants in micelles and monolayers. The pH vs concentration plots, on the other hand, showed a distinct difference between 4-C12-DTPA complexes of the alkaline earth metals and the transition metals. This was explained by the difference in coordination between the two groups of metal ions, as predicted by the hard and soft acid and base (HSAB) theory.

  • 23.
    Svanedal, Ida
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Boija, Susanne
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Norgren, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Edlund, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Headgroup interactions and ion flotation efficiency in mixtures of a chelating surfactant, different foaming agents and divalent metal ions2014In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 30, no 22, p. 6331-6338Article in journal (Refereed)
    Abstract [en]

    The correlation between interaction parameters and ion flotation efficiency in mixtures of chelating surfactant metal complexes and different foaming agents was investigated. We have recently shown that chelating surfactant 2-dodecyldiethylenetriaminepentaacetic acid (4-C-12-DTPA) forms strong coordination complexes with divalent metal ions, and this can be utilized in ion flotation. Interaction parameters for mixed micelles and mixed monolayer formation for Mg2+ and Ni2+ complexes with the chelating surfactant 4-C-12-DTPA and different foaming agents were calculated by Rubingh's regular solution theory. Parameters for the calculations were extracted from surface tension measurements and NMR diffusometry. The effects of metal ion coordination on the interactions between 4-C-12-DTPA and the foaming agents could be linked to a previously established difference in coordination chemistry between the examined metal ions. As can be expected from mixtures of amphoteric surfactants, the interactions were strongly pH-dependent. Strong correlation was found between interaction parameter beta(sigma)for mixed monolayer formation and the phase-transfer efficiency of Ni2+ complexes with 4-C-12-DTPA during flotation in a customized flotation cell. In a mixture of Cu(2+)and Zn2+, the significant difference in conditional stability constants (log K) between the metal complexes was utilized to selectively recover the metal complex with the highest log K (Cu2+) by ion flotation. Flotation experiments in an excess concentration of metal ions confirmed the coordination of more than one metal ion to the headgroup of 4-C-12-DTPA.

  • 24.
    Svanedal, Ida
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Persson, Gerd
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Norgren, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Edlund, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Anomalies in Solution Behavior of an Alkyl Aminopolycarboxylic Chelating Surfactant2013In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 29, no 45, p. 13708-13716Article in journal (Refereed)
    Abstract [en]

    The solution behavior of a DTPA (diethylenetriaminepentaacetic acid)-based chelating surfactant, 4-C12-DTPA, has beenstudied by tensiometry and NMR diffusometry. In the absence of metalions, the eight donor atoms in the headgroup are titrating, and thecharge of the headgroup can thus be tuned by altering the pH. 4-C12-DTPA changes from cationic at very low pH, over a number ofzwitterionic species as the pH is increased, and eventually becomesanionic at high pH. Around the isoelectric point, the chelatingsurfactant precipitated. The solution properties, studied above thesolubility gap, were found strongly pH dependent. When increasing theamount of negative charges in the headgroup, by increasing the pH, theadsorption efficiency was reduced and the cmc was increased. Anoptimum in surface tension reduction was found at pH 5, due to aproper balance between protonated and dissociated groups. Anomaliesbetween surface tension measurements and NMR diffusometry in determination of cmc revealed a more complex relationbetween surface tension, surface coverage, and cmc than usually considered, which is not in line with the common interpretationof the Gibbs adsorption equation. At some of the investigated pH levels, measurements of bulk pH could confirm the location ofcmc, due to the increased protonation of micelles compared to monomers in solution. The adsorption of monomers to the air−water interface showed unusually slow time dependence, evident from decreasing surface tension for several hours. This isexplained by rearrangements of the large head groups to reduce the headgroup area and increase the packing parameter.

  • 25.
    Svanedal, Ida
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Persson, Gerd
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Norgren, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Edlund, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Interactions in Mixed Micellar Systems of an Amphoteric Chelating Surfactant and Ionic Surfactants2014In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 30, no 5, p. 1250-1256Article in journal (Refereed)
    Abstract [en]

    Mixtures of ionic surfactants and the chelating surfactant 2-dodecyldiethylenetriaminepentaacetic acid (4-C12-DTPA) have been examined in terms of interactions in mixed micellar systems. The amphoteric 4-C12-DTPA is zwitterionic with a negative net charge at the studied pH levels. The investigated ionic surfactants were the cationic dodecyltrimethylammonium chloride (DoTAC), the anionic sodium dodecyl sulfate (SDS), and the zwitterionic dimethyldodecylamine-N-oxide (DDAO). The surfactants all have the same hydrophobic chain lengths, and the results are evaluated in terms of headgroup interactions. 4-C12-DTPA interacts with different ionic surfactants by accepting or donating protons to the aqueous solution to increase the attractive interactions between the two surfactants; i.e., the protonation equilibrium of 4-C12-DTPA is shifted in different directions depending on whether there are predominant repulsions between positively or negatively charged groups in the mixed micelles. This was monitored by measuring pH vs concentration in the mixed systems. By measuring the pH, it was also possible to study the shift in the protonation equilibrium at increasing concentration, as the composition in the micelles approaches the composition in the total solution. Following the approach of Rubingh's regular solution theory, the interaction parameter β for mixed micelle formation was calculated from the cmc values determined by NMR diffusometry. Synergism in mixed micelle formation and negative β parameters were found in all of the investigated systems. As expected, the most negative β parameter was found in the mixture with DoTAC, followed by DDAO and SDS. The self-diffusion in the 4-C12-DTPA/DoTAC system was also discussed. The self-diffusion coefficient vs concentration plots show two distinctly different curves, depending on the surfactant that is present in excess.

  • 26.
    Volpati, Diogo
    et al.
    University of São Paulo, Brazil.
    Aoki, Pedro H. B.
    UNESP, Brazil.
    Alessio, Priscila
    UNESP, Brazil.
    Pavinatto, Felippe J.
    University of São Paulo, Brazil.
    Miranda, Paulo B.
    University of São Paulo, Brazil.
    Constantino, Carlos J. L.
    UNESP, Brazil.
    Oliveira, Osvaldo N., Jr.
    University of São Paulo, Brazil.
    Vibrational spectroscopy for probing molecular-level interactions in organic films mimicking biointerfaces2014In: Advances in Colloid and Interface Science, ISSN 0001-8686, E-ISSN 1873-3727, Vol. 207, no Special Issue: Helmuth Möhwald Honorary Issue, p. 199-215Article in journal (Refereed)
    Abstract [en]

    Investigation into nanostructured organic films has served many purposes, including the design of functionalized surfaces that may be applied in biomedical devices and tissue engineering and for studying physiological processes depending on the interaction with cell membranes. Of particular relevance are Langmuir monolayers, Langmuir-Blodgett (LB) and layer-by-layer (LbL) films used to simulate biological interfaces. In this review, we shall focus on the use of vibrational spectroscopy methods to probe molecular-level interactions at biomimetic interfaces, with special emphasis on three surface-specific techniques, namely sum frequency generation (SFG), polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS) and surface-enhanced Raman scattering (SERS). The two types of systems selected for exemplifying the potential of the methods are the cell membrane models and the functionalized surfaces with biomolecules. Examples will be given on how SFG and PM-IRRAS can be combined to determine the effects from biomolecules on cell membrane models, which include determination of the orientation and preservation of secondary structure. Crucial information for the action of biomolecules on model membranes has also been obtained with PM-IRRAS, as is the case of chitosan removing proteins from the membrane. SERS will be shown as promising for enabling detection limits down to the single-molecule level. The strengths and limitations of these methods will also be discussed, in addition to the prospects for the near future.

  • 27.
    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 spectroscopies2015In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 460, p. 290-302Article in journal (Refereed)
    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.

  • 28.
    Wakeham, D.
    et al.
    Centre for Organic Electronics, University of Newcastle, Callaghan, NSW 2308, Australia.
    Niga, Petru
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media. KTH Royal Inst Technol, Dept Chem Surface & Corros Sci, SE-10044 Stockholm, Sweden.
    Ridings, C
    Centre for Nano Scale Science and Technology, Flinders University, SA 5001, Australia.
    Andersson, G
    Centre for Nano Scale Science and Technology, Flinders University, SA 5001, Australia.
    Nelson, A
    Bragg Institute, Australian Nuclear Science and Technology Organisation, PMB 1, Menai, NSW 2234, Australia.
    Warr, G
    School of Chemistry, University of Sydney, NSW 2006, Australia.
    Baldelli, S
    Department of Chemistry, University of Houston, Houston, TX 77204-5003, United States.
    Rutland, M
    Department of Chemistry, Surface and Corrosion Science, KTH Royal Institute of Technology, Drottning Kristinas Väg 51, SE-100 44 Stockholm, Sweden.
    Atkin, R
    Centre for Organic Electronics, University of Newcastle, Callaghan, NSW 2308, Australia.
    Surface structure of a "non-amphiphilic" protic ionic liquid2012In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 14, no 5, p. 5106-5114Article in journal (Refereed)
    Abstract [en]

    The nanostructure of the ethanolammonium nitrate (EtAN)-air surface has been investigated using X-ray reflectometry (XRR), vibrational sum frequency spectroscopy (VSFS) and neutral impact collision ion scattering spectroscopy (NICISS). The XRR data decays more rapidly than expected for a perfectly sharp interface, indicating a diffuse electron (scattering length) density profile. Modelling of the XRR data using three different fitting routines produced consistent interfacial profiles that suggest the formation of interfacial EtAN clusters. Consistent with this, VSFS reveals that the EtAN surface is predominantly covered by -CH 2- moieties, with the -NH 3 + and -OH groups of the cation buried slightly deeper in the interface. The elemental profiles determined using NICISS also show enrichment of carbon relative to nitrogen and oxygen in the outermost surface layer, which is consistent with the surface cation orientation deduced from VSFS, and with the presence of EtAN aggregates at the liquid surface. © 2012 the Owner Societies.

  • 29.
    Zasadowski, Dariusz
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    REMOVAL OF LIPOPHILIC EXTRACTIVES AND MANGANESE IONS FROM SPRUCE TMP WATER BY FLOTATION2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Dissolved and Colloidal substances (DisCo) and metals are released from wood during thermomechanical pulp (TMP) production. The mechanical treatment causes that these components have a tendency to accumulate in process waters, as the water circulation systems in integrated paper mills are being closed. Disturbances such as pitch depositions on the paper machine (pitch problems), specks in the paper, decreased wet and dry strength, interference with cationic process chemicals, and impaired sheet brightness and friction properties appear in the presence of DisCo substances. The presence of transition metal ions such as manganese results in higher consumption of bleaching chemicals (hydrogen peroxide) and lowers the optical quality of the final product, and addition of complexing agents, such as EDTA or DTPA, to prevent this is needed. The never ending trends to decrease water consumption and increase process efficiency in pulp and paper production stress that it is very important both to know the effects of wood substances on pulping and papermaking and to be able to remove them in an efficient way.

    Carried out investigations presented in this thesis show that the lipophilic extractives can be removed from TMP press water to high extent. A 90% decrease in turbidity and a 91% removal of lipophilic extractives from TMP press water can be obtained by addition of a cationic surfactant as foaming agent during flotation. Additionally, fibres located in TMP press water are not removed with the foam fraction but purified. A retained concentration of hydrophilic extractives in the process water indicates that the flotation is selective. Moreover, by introduction of a new recoverable surface active complexing agent, a chelating surfactant, manganese ions in the form of chelates can be successfully removed from the pulp fibres and separated from the process water in the same flotation process.

    iii

    The findings presented above indicate new possibilities for internal water cleaning and decreased emissions to water if flotation technology is applied in an integrated mechanical pulp mill.

  • 30.
    Öhlund, Thomas
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Metal Films for Printed Electronics: Ink-substrate Interactions and Sintering2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    A new manufacturing paradigm may lower the cost and environmental impact of existing products, as well as enable completely new products. Large scale, roll-to-roll manufacturing of flexible electronics and other functionality has great potential. However, a commercial breakthrough depends on a lower consumption of materials and energy compared with competing alternatives, and that sufficiently high performance and reliability of the products can be maintained. The substrate constitutes a large part of the product, and therefore its cost and environmental sustainability are important. Electrically conducting thin films are required in many functional devices and applications. In demanding applications, metal films offer the highest conductivity.

     

    In this thesis, paper substrates of various type and construction were characterized, and the characteristics were related to the performance of inkjet-printed metal patterns. Fast absorption of the ink carrier was beneficial for well-defined pattern geometry, as well as high conductivity. Surface roughness with topography variations of sufficiently large amplitude and frequency, was detrimental to the pattern definition and conductivity. Porosity was another important factor, where the characteristic pore size was much more important than the total pore volume. Apparent surface energy was important for non-absorbing substrates, but of limited importance for coatings with a high absorption rate. Applying thin polymer–based coatings on flexible non-porous films to provide a mechanism for ink solvent removal, improved the pattern definition significantly. Inkjet-printing of a ZnO-dispersion on uncoated paper provided a thin spot-coating, allowing conductivity of silver nanoparticle films. Conductive nanoparticle films could not form directly on the uncoated paper.

     

    The resulting performance of printed metal patterns was highly dependent on a well adapted sintering methodology. Several sintering methods were examined in this thesis, including conventional oven sintering, electrical sintering, microwave sintering, chemical sintering and intense pulsed light sintering. Specially designed coated papers with modified chemical and physical properties, were utilized for chemical low-temperature sintering of silver nanoparticle inks. For intense pulsed light sintering and material conversion of patterns, custom equipment was designed and built. Using the equipment, inkjet-printed copper oxide patterns were processed into highly conducting copper patterns. Custom-designed papers with mesoporous coatings and porous precoatings improved the reliablility and performance of the reduction and sintering process.

     

     

     

     

    The thesis aims to clarify how ink-substrate interactions and sintering methodology affect the performance and reliability of inkjet-printed nanoparticle patterns on flexible substrates. This improves the selection, adaptation, design and manufacturing of suitable substrates for inkjet-printed high conductivity patterns, such as circuit boards or RFID antennas.  

  • 31.
    Öhlund, Thomas
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Schuppert, Anna
    Institut Charles Gerhardt de Montpellier, France.
    Hummelgård, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Bäckström, Joakim
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Nilsson, Hans-Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Olin, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Inkjet Fabrication of Copper Patterns for Flexible Electronics: Using Paper with Active Precoatings2015In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 7, no 33, p. 18273-18282Article in journal (Refereed)
    Abstract [en]

    Low-cost solution-processing of highly conductive films is important for the expanding market of printed electronics. For roll-to-roll manufacturing, suitable flexible substrates and compatible postprocessing are essential. Here, custom-developed coated papers are demonstrated to facilitate the inkjet fabrication of high performance copper patterns. The patterns are fabricated in ambient conditions using water-based CuO dispersion and intense pulsed light (IPL) processing. Papers using a porous CaCO3 precoating, combined with an acidic mesoporous absorption coating, improve the effectiveness and reliability of the IPL process. The processing is realizable within 5 ms, using a single pulse of light. A resistivity of 3.1 ± 0.12 μΩ·cm is achieved with 400 μm wide conductors, corresponding to more than 50% of the conductivity of bulk copper. This is higher than previously reported results for IPL-processed copper.

  • 32. Örtegren, Jonas
    et al.
    Wantke, Klaus-Dieter
    Motschmann, Hubert
    An oscillating bubble device for direct measurement of molecular exchange processes at the air-liquid interface in the medium frequency range2003In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 74, no 12, p. 5167-5172Article in journal (Refereed)
    Abstract [en]

    An experiment for the investigation of the exchange dynamics of adsorbed and dissolved surfactantsat the air–water interface is described. The experiment combines two established techniques: themethod of the oscillating bubble generates in a well-defined fashion a nonequilibrium state by aperiodic compression and expansion of the surface layer. The state of the adsorption layer is theninvestigated by surface second harmonic generation ~SHG!. SHG is a second order nonlinear opticaltechnique, which probes only the adsorbed molecules. Contribution of the bulk is widely suppressedand information on the orientational order of the surfactant and the corresponding number densityof the adsorbed species are gained. These data are of utmost importance to assess the establishedmodels of Gibbs adsorption layer. The combination of the nonlinear optical technique with a rapidlyoscillating bubble imposes severe experimental hurdles such as the synchronization of the laserpulses with the state of the bubble or problems arising from a bad signal to noise ratio. Theexperimental setup discussed in this article overcomes these problems and outlines all relevantdesign parameters.

  • 33. 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 bubble2004In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 279, p. 266-276Article in journal (Refereed)
    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.

1 - 33 of 33
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