| 1. |
- Agerkvist, I, et al.
(author)
-
Selective flocculation with chitosan in E.Coli disintegrates: effects of ionic strength and multivalent metal ions
- 1993
-
In: Journal of Dispersion Science and Technology. - 0193-2691 .- 1532-2351. ; 14, s. 269-293
-
Journal article (peer-reviewed)abstract
- The effects of ionic strength and multivalent metal ions on the flocculation performance in Escherichia coli cell disintegrates using the polycationic chitosan as a flocculant were investigated. The study showed that ionic strength could be used to optimize the selectivity in flocculation. The best selectivity was obtained at 0.5 M sodium chloride where 95% of the cell debris and 88% of the nucleic acids could be removed from the disintegrate by sedimentation, leaving 99% of proteins and 86% of -galactosidase enzyme activity in clarified solution. We will also discuss the mechanisms for interaction between chitosan and different groups of components in the disintegrate: cell debris particles, nucleic acid polymers and proteins.
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| 2. |
- Almgren, Mats
(author)
-
Vesicle transformations resulting from curvature tuning in systems with micellar, lamellar, and bicontinuous cubic phases
- 2007
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 28:1, s. 43-54
-
Journal article (peer-reviewed)abstract
- LCNP, liquid crystalline nanoparticles, are dispersions of liquid crystalline phases in excess solvent, usually water. Vesicles are the ones derived from the lamellar phase, and are characterized by a spontaneous monolayer curvature close to zero, or a surfactant packing parameter close to one. By changing the composition of amphiphile mixtures, the spontaneous curvature may be changed. This results in a change of the phase behavior as well as in the stability and morphology of the dispersed particles. This article reviews such changes mainly for systems based on polar lipid amphiphiles such as lecithins and glycerylmonooleate mixed with surfactants or amphiphilic block copolymers. Perforated vesicles, stomatosomes, are paid particular attention, not because of their importance as LCNP, but simply because they are least well known. As a tribute to Per Ekwall, some cryoTEM micrographs of vesicles from the “holy system,” sodium caprylate-decanol-water, are presented. Stomatosomes were not found in that system.
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| 3. |
- Antunes, FE, et al.
(author)
-
Ionization by pH and Anionic Surfactant Binding Gives the Same Thickening Effects of Crosslinked Polyacrylic Acid Derivatives
- 2012
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 33:9, s. 1368-1372
-
Journal article (peer-reviewed)abstract
- Physical properties of aqueous solutions of hydrophobically modified crosslinked polyacrylic acids change quite extensively as the polymer is charged up. A study is carried out concerning the similarities between two polymer ionization processes, that is, by pH increment and anionic surfactant addition. The two processes charge the polymer by distinctly different mechanisms. At sufficiently high pH the carboxylic groups of the polymer are virtually all ionized and the polymer is, therefore, fully charged. The effective repulsion among the charged groups due to the entropy of the counterions promotes an increased stiffness as well as an expansion of the polymer particles. We investigate here how the ionization and swelling will be if, instead of high pH, the polymer is at low pH conditions but associated to ionic surfactants. Surfactants associate to the polymer both in a noncooperative way by the binding of individual surfactant molecules and in a cooperative way as micelles since the polymer promotes surfactant self-assembly. This binding leads to a highly charged polymer-surfactant complex and leads to an osmotic swelling as well. The swelling and the gelation were monitored by rheology and dynamic light scattering, of polymer solutions by varying the pHs and adding ionic surfactants at low pH. The results show that ionization by surfactants and by pH lead to approximately the same gelation degree, as can be seen by similar viscosity values. Both processes result in dramatic viscosity increases, up to 8 orders of magnitude. More hydrophobic surfactants, with longer alkyl chain, are shown to be more efficient as enhancers of swelling and gelation. The network that is formed at high pH or at sufficiently high concentration of surfactant can be weakened or even disrupted if monovalent or divalent salts are added, demonstrating the role of counterion entropy.
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| 4. |
- Arkhipov, Viktor P., et al.
(author)
-
Dynamic and structural properties, cloud point of mixed micelles of oxyethylated isononylphenols
- 2021
-
In: Journal of Dispersion Science and Technology. - : Taylor & Francis. - 0193-2691 .- 1532-2351. ; 42:2, s. 278-285
-
Journal article (peer-reviewed)abstract
- We measured the self-diffusion coefficients of mixed micelles formed in binary mixtures of oxyethylated isononylphenols (neonols) AF9-2,3,4,6,8,9,10,12 by NMR diffusometry in aqueous 1 wt% solutions. The effective hydrodynamic radii of the micelles were calculated using the Stokes-Einstein relation. Cloud points of these solutions were determined visually and the relation between the cloud point and the composition of the mixture was suggested. Extraction of phenol from the solutions at their cloud points was also studied.
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| 5. |
- Arkhipov, Victor P., et al.
(author)
-
The cloud point of aqueous solutions of ethoxylated monoalkylphenols in the individual state and in the presence of electrolytes
- 2018
-
In: Journal of Dispersion Science and Technology. - : Taylor & Francis. - 0193-2691 .- 1532-2351. ; 39:10, s. 1442-1446
-
Journal article (peer-reviewed)abstract
- The cloud points tcp of aqueous solutions of ethoxylated monoalkylphenols, AF9-n (n = 8,9,10,12), were measured in the concentration (C) range of 0.25-40 wt.%. tcp increased as C decreased at C < 1 wt.%. At 1 < С < 10 wt.%, tcp changed insignificantly; Δtcp/tcp did not exceed 5%. Solutions transformed into the gel state at С > 10-20 wt.% and tcp sharply increased. The dependence of tcp on the length of the oxyethylene chains of ethoxylated nonylphenols at C = 1 wt.% can be described by the equation tcp = b·ln(n-n0), where n0 = 6. The cloud points of aqueous solutions (C = 1 wt.%) of the ethoxylated nonylphenols were measured at different concentrations of NaI, NaCl, NaF, Na2CO3, and Na2SO4 salts. For all of these solutions, tcp decreased in the presence of NaCl, NaF, Na2CO3, Na2SO4 and increased in the presence of NaI. To describe the dependence of tcp on the salt concentration, the equation was suggested, where and tcp are the cloud points of a neat aqueous solution of ethoxylated nonylphenols and of the solution in the presence of electrolytes, respectively.
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| 6. |
- Awad, Tarek, et al.
(author)
-
Colloidal Structure and Physical Properties of Gel Networks Containing Anionic Surfactant and Fatty Alcohol Mixture
- 2011
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 32:6, s. 807-815
-
Journal article (peer-reviewed)abstract
- We investigated the mechanical properties, thermal behavior, physical state, and colloidal structure of a model gel network formulated with various ratios of sodium dodecyl sulfate polyacrylamide (SDS) and cetyl/stearyl fatty alcohol (FA) mixture in constant amounts of water (89%). The metastable gel, formed by slowly cooling stirred samples from temperatures above the chain melting temperature (Tm) of the long chain FA, has a lamellar structure with a periodic inter bilayer spacing of approximately 30nm. The bilayers remain homogeneous with SDS being immobilized in the FA matrix upon chain freezing. The chain length mismatch leads to an increased structural disorder among the alkyl chains upon SDS incorporation among the FA. As a result, the elastic modulus decreased with increasing SDS content. Conclusions were based on a large number of experiments involving differential scanning calorimetry, rheology, 1H NMR spectroscopy, and small angle x-ray scattering. Results from this work have uncovered the physical nature of these networks and gave insight into the role of anionic surfactants on the assembly, physical state, and mechanical properties of gel networks.
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| 7. |
- Balogh, Joakim, et al.
(author)
-
Dependence on oil chain-length of the curvature elastic properties of nonionic surfactant films: Droplet growth from spheres to a bicontinuous network
- 2007
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 28:2, s. 223-230
-
Journal article (peer-reviewed)abstract
- Using NMR self-diffusion and H-2-NMR relaxation experiments, we have investigated growth of oil-in-water microemulsion droplets when spontaneous curvature is lowered, starting at emulsification failure boundary. We compare two ternary nonionic microemulsion systems, containing penta-ethylene glycol dodecyl ether (C12E5), and decane or hexadecane, at same surfactant-to-oil ratio and approximately the same spontaneous curvature. Droplet growth in microemulsions appears in general to be only minor. Quantitative differences between the two systems indicate differences in the curvature elastic constants.
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| 8. |
- Balogh, Joakim, et al.
(author)
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Dependence on oil chain length of the curvature elastic properties of nonionic surfactant films: Emulsification failure and phase equilibria
- 2006
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 27:4, s. 497-510
-
Journal article (peer-reviewed)abstract
- We compare two ternary microemulsions, stabilized by the nonionic surfactant pentaethylene-glycol-dodecyl-ether (C12E5), containing decane or hexadecane. The comparison involves phase behavior and properties of O/W droplet microemulsions investigated with SAXS, static and dynamic light scattering, and NMR. Striking differences are observed. The systems are analyzed in terms of curvature elastic properties of surfactant film. Apart from an increase of the spontaneous curvature, there also appears to be a small but significant increase in the saddle splay constant as the oil chain length is increased.
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| 9. |
- Blomberg, E, et al.
(author)
-
Adsorbed layers of human serum albumin investigated by the surface force technique
- 1991
-
In: Journal of Dispersion Science and Technology. - 0193-2691 .- 1532-2351. ; 12, s. 179-200
-
Journal article (peer-reviewed)abstract
- The interactions between human serum albumin (HSA) layers adsorbed from solution onto muscovite mica have been investigated by means of surface force measurements. The effects of varying the ionic strength and the serum albumin concentration have been studied at pH=5.5. The negatively charged protein cannot be desorbed from the negatively charged mica surface by dilution with water. The thickness of the (compressed) adsorbed layer is small compared to the dimension of HSA, except at the highest concentration used (1mg/ml). Hence, under a compressive load at low packing densities the protein conformation on the surface is different from that in bulk solution. No adhesion was observed when the amount adsorbed was large. However, an attractive
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| 10. |
- Blomberg, E, et al.
(author)
-
Interactions between poly(ethylene oxide) coated surfaces and between such surfaces and proteins
- 1998
-
In: Journal of Dispersion Science and Technology. - 0193-2691 .- 1532-2351. ; 19, s. 1107-1126
-
Journal article (peer-reviewed)abstract
- Surfaces coated with poly(ethylene oxide) containing nonionic polymers are of interest in medical applications due to, among other things, the low adsorption of proteins on such surfaces. In this paper we have studied the interfacial properties of surfaces coated with PEO by measuring the forces acting between two such surfaces in water and across a protein solution as well as between one such surface and a surface carrying adsorbed proteins. One type of surface coating was a graft copolymer of poly(ethylene imine) and poly(ethylene oxide) where the cationic poly(ethylene imine) group anchored the polymer to negatively charged mica surfaces. Three different ways to prepare this coating was used and compared. It was found that this coating was not stable in the presence of lysozyme, a small positively charged protein, when the PEO graft density was low. The other type of coating was obtained by adsorbing ethyl(hydroxyethyl)-cellulose onto hydrophobised mica surfaces. The driving force for adsorption is in this case the hydrophobic interaction between nonpolar segments of the polymer and the surface. The EHEC coating was stable in the presence of lysozyme and the interactions between adsorbed layers of lysozyme and EHEC coated surfaces are purely repulsive due to long-range steric forces.
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| 11. |
- Boissier, Catherine, 1972, et al.
(author)
-
Water-Based Latex Dispersions. 5: NMR Relaxation Studies of Deuterium Labeled Nonylphenol Ethoxylate
- 2009
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 1532-2351 .- 0193-2691. ; 30:6, s. 873-880
-
Journal article (peer-reviewed)abstract
- The dynamics and conformation of the nonionic surfactant NP100 (nonylphenol ethoxylate with an average of 84 oxyethylene units), adsorbed on colloidal silica and on polystyrene latex particles, have been studied by the nuclear magnetic resonance relaxation technique. To obtain specific information about the spin relaxation from the methylene groups situated at the hydroxyl-terminal end of the polyoxyethylene (POE) chain, this part was labeled with deuterium in a two-step synthesis. Spin relaxation studies of the labeled part of the adsorbed surfactant (2H relaxation) suggested that the dynamics was slower in comparison with the spin relaxation of the surfactant in solution. Also, it was seen that the dynamics was slower on the silica surface than on the polystyrene surface. This was in agreement with previous studies on the average proton spin relaxation of the whole POE chain of the surfactant on silica and on polystyrene surfaces. The correlation time constant for the slow motions of the POE chain was calculated to be as large as 7.4 ms for NP100 on the polystyrene particles. Also this was in good agreement with studies made on the exchange dynamics of the surfactant in different dispersions, where it was found that the exchange between the solution and the particles was slow.
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| 12. |
- Butakov, Anatoly, et al.
(author)
-
Peculiarities of NMR relaxation in micellar gels of Pluronic F-127
- 2019
-
In: Journal of Dispersion Science and Technology. - : Taylor & Francis. - 0193-2691 .- 1532-2351. ; 40:3, s. 403-407
-
Journal article (peer-reviewed)abstract
- Based on the 1H relaxation of transverse nuclear magnetization of triblock-copolymer Pluronic F-127 in D2O, we proposed a model of the associated pluronic structure in which the polyethylene oxide of molecules in neighboring micelles are intertwined in regions of overlapping micellar coronas, while the polypropylene oxide cores of the micelles play a role of nodes in the 3D network.
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| 13. |
- Carlfors, J, et al.
(author)
-
Lidocaine in microemulsion - A dermal delivery system
- 1991
-
In: Journal of Dispersion Science and Technology. - 0193-2691 .- 1532-2351. ; 12, s. 467-482
-
Journal article (peer-reviewed)abstract
- In order to obtain a microemulsion that is stable at skin tempeature, the regions of existance of microemulsions of water and isoproptyl myristate were studied as a function of hydrophilelipophile balance (HLB) of nonionic surfactant mixtures. The microemulsion dissolves large amount of the local anaesthetic lidocaine. The amount of dissolved lidocaine in the microemulsion was proportional to the isopropyl myristate content and limited to its solubility in this solvent. The addition of lidocaine lowered the phase inversion temperature (PIT) of the system and increased the temperature range for microemulsion stability. The structure of the microemulsion, as investigated by proton Fourier transform pulsed-gradient spin-echo NMR spectroscopy, was found to be bicontinous. The physico-chemical properties of the microemulsion as well as the low toxicity of its components result in formulation intendend for topical administation.
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| 14. |
- Claesson, PM, et al.
(author)
-
New surfaces and techniques for studies of interparticle forces
- 1994
-
In: Journal of Dispersion Science and Technology. - 0193-2691 .- 1532-2351. ; 15, s. 375-397
-
Journal article (peer-reviewed)abstract
- Several methods of preparing surfaces suitable for interparticle surface forces measurements are presented. Treatment of muscovite mica surfaces with a water vapour plasma introduces surface hydroxyl groups. These groups can react with chlorosilanes to form organo functionalized surfaces. The forces between water vapour plasma treated mica surfaces in aqueous solutions are well described by DLVO theory except for the presence of a short-range (D < 10 Å) additional repulsion. After reaction with a fluorocarbon containing silane the surfaces become hydrophobic and a long-range attraction acts between the surfaces in water. Smooth glass spheres can be obtained by melting a glass rod in a gas burner. These surfaces are ideal substrates for a new type of surface force apparatus that uses a bimorph force sensor for measuring surface forces. The chemistry of the glass surfaces is readily modified by reactions with chlorosilanes. The similarities and the differences between the forces acting between glass and water vapour plasma treated mica surfaces before and after silanation are discussed. We also report on the use of a cold plasma process to produce thin, smooth organic films that can be investigated with the surface force technique.
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| 15. |
- Costa, Diana, et al.
(author)
-
Modeling the Surfactant Uptake in Cross-Linked DNA Gels
- 2009
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 30:6, s. 954-960
-
Journal article (peer-reviewed)abstract
- The deswelling behavior of cross-linked DNA gels reports on DNA-cosolute interactions and gives a basis for the development of responsive DNA formulations. An investigation of the deswelling kinetics shows that an increase in the surfactant tail length gives a pronouncedly slower deswelling kinetics. In the same conditions, single stranded gels exhibited faster deswelling kinetics when compared with double stranded networks. It was also found that DNA gels display a nonmonotonic volume change with time, deswelling followed by reswelling, when immersed in surfactant solutions. Kinetic modeling of surfactant uptake by the DNA gel was done using a stochastic approach of mass transfer between the bulk solution, the surface, and the inner volume of the gels. Diffusion coefficients and kinetic constants can be derived from the separated model uptake curves for the gel surface and the gel interior volume.
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| 16. |
- Dunér, Gunnar, et al.
(author)
-
Friction between surfaces - Polyacrylic acid brush and silica - mediated by calcium ions
- 2010
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 31:10, s. 1285-1287
-
Journal article (peer-reviewed)abstract
- With this letter, we report how friction can be controlled by inducing physical bonds solely within a polyelectrolyte brush layer, while keeping repulsive interactions between the brush layer and the bare surface that slides above. Our results imply that the nature of the bare surface is of minor importance as long as the repulsive surface interaction is maintained.
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| 17. |
- Ejenstam, Lina, 1985-, et al.
(author)
-
Towards superhydrophobic polydimethylsiloxane-silica particle coatings
- 2016
-
In: Journal of Dispersion Science and Technology. - : Taylor & Francis. - 0193-2691 .- 1532-2351. ; 37:9, s. 1375-1383
-
Journal article (peer-reviewed)abstract
- Hydrophobized silica nanoparticles of different sizes, from 16 to 500 nm, were used to impart roughness to a hydrophobic polydimethylsiloxane (PDMS) coating with the aim of obtaining superhydrophobic properties. The particle silanization process and the curing process of the PDMS coating were optimized to increase the contact angle of the particle containing coating. The evaluation of the coatings, by means of water contact angle measurements and scanning electron microscopy imaging, show that superhydrophobicity in the adhesive rose state was achieved using combinations of two differently sized particles, with an excess of the small 16 nm ones. Superhydrophobicity in the Lotus state was obtained when the filler concentration of 16 nm particles was 40 wt%, but under such conditions the coating was found to partially crack, which is detrimental in barrier applications. The preference for the rose wetting state can be explained by the round shape of the particles, which promotes the superhydrophobic rose wetting state over that of the superhydrophobic Lotus state.
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| 18. |
- Friberg, SE, et al.
(author)
-
Hydrotropes – performance chemicals
- 2004
-
In: Journal of Dispersion Science and Technology. - 0193-2691 .- 1532-2351. ; 25, s. 243-251
-
Journal article (peer-reviewed)abstract
- The action of hydrotropes is reviewed emphasizing their influence in the formation of microemulsions, vesicle solutions and other products involving surfactant association structures. It is demonstrated that the hydrotropes, the association structures of which, realistically, can only be described as trivial, actually, are powerful and sophisticated performance chemicals playing an essential role in complex applied formulations utilizing more composite amphiphilic association structures
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| 19. |
- He, Yunjuan, et al.
(author)
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Comparative study of CNC and CNF as additives in waterborne acrylate-based anti-corrosion coatings
- 2020
-
In: Journal of Dispersion Science and Technology. - : Taylor & Francis. - 0193-2691 .- 1532-2351. ; 41:13, s. 2037-2047
-
Journal article (peer-reviewed)abstract
- Nanocomposite coatings are of great interest as barrier coatings since synergy effects between matrix and additive properties can be achieved. This, however, requires favorable additive-matrix interactions to provide a strong interphase (interface region). In this work we elucidate the properties of two environmentally benign nanocomposite coatings based on a waterborne acrylate formulation with additives from renewable sources, i.e. either cellulose nanocrystals, CNC; or, alternatively, cellulose nanofibrils, CNF. We focus on the corrosion protective properties of these coatings and discuss the reason why the nanocomposite with CNC displays favorable corrosion protection properties whereas that with CNF does not. To this end we utilized scanning electron microscopy, water contact angle measurement, Fourier transform infrared spectroscopy and electrochemical impedance spectroscopy techniques to investigate the microstructure, surface wetting, interactions between cellulosic materials and matrix as well as corrosion protective properties of both composite coatings.
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| 20. |
- Holmberg, K, et al.
(author)
-
Journal of dispersion science and technology : Special issue : YKI 25 years
- 1994
-
In: Journal of Dispersion Science and Technology. - 0193-2691 .- 1532-2351. ; 15, s. 251-399
-
Journal article (peer-reviewed)abstract
- INTRODUCTION; The Institute for Surface Chemistry - YKI - celebrates its 25th anniversary this year. The Institute, located in Stockholm, Sweden, has played an active part in the development of surface chemistry for various technological applications. The development in this field has been rapid. In the end of the 60's, surface chemistry was a relatively unknown discipline both in academia and in industry; today it is seen as one of the most dynamic areas in chemistry and as a technology of vital importance in industrial branches ranging from pharmaceuticals to paper making. Already in 1962 a laboratory for surface chemistry was founded in Stockholm. The laboratory, headed by Professor Per Ekwall from Finland, grew in size. In 1968, it got the status of an institute. Stig Friberg became the first Director and held the position until 1977. During this period, YKI industrial support was established through the Foundation for Surface Chemistry with members from all Scandinavian countries. The research heritage from Per Ekwall proved fruitful both from a scientific and an applied point of view with active industrial interaction through technical sections in a number of branches. During these years the Institute acquired a solid international reputation. Friberg was succeeded by Ekwall's former student Per Stenius who stayed as Director until 1991. During these years YKI strengthened its positions in several important fields of applied surface chemistry, such as paper making, mineral ore flotation and surface and colloid chemistry related to coatings. An important step on the more fundamental side was the establishment of a research group in the field of surface force measurements. Research in this area has been rewarding and the activity has expanded. The Stockholm group which through the years has maintained close contact with the Canberra group is one of the leading in this field today. YKI today is an institute with a large scientific network all over the world. Active collaboration is maintained with research groups in many countries and the Institute receives a large number of guest scientists each year. What started as a Swedish Institute developing into a Scandinavian organization has now become a truly international operation. Each year YKI arranges an international symposium on applied surface chemistry. This special issue of the lournal of Dispersion Science and Technology contains contributions by invited speakers of this year's meeting, held in Copenhagen, Denmark, in November 1993 and hosted by Novo Nordisk A/S.
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| 21. |
- Horie, Wataru, et al.
(author)
-
Formation of reverse vesicles in silicone surfactant systems
- 2017
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 38:12, s. 1804-1810
-
Journal article (peer-reviewed)abstract
- This study deals with the formation of reverse vesicles based on the phase behavior of silicone surfactants. The surfactants, polyoxyethylene–polydimethylsiloxane and polyoxyethylene–polyoxypropylene–polydimethylsiloxane copolymer, were found to form lamellar liquid crystal phases in three different types of silicone oil upon the addition of a certain amount of water. A conventional method in which reverse vesicles are prepared by physically dispersing this lamellar liquid crystal phase in oil was employed in addition to a technique based on a temperature-induced phase transition. The particle sizes and stabilities of the resulting reverse vesicles were evaluated.
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| 22. |
- Jausovec, D., et al.
(author)
-
Enzymatic Degradation of Model Cellulose Film Pre-Treated with Antimicrobial Agent
- 2009
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 30:6, s. 929-936
-
Journal article (peer-reviewed)abstract
- Enzymatic degradation of model cellulose films pre-treated with antimicrobial agent, 3-(trimethoxysilyl)-propyldimethyloctadecyl ammonium chloride (TMPAC) was investigated. AFM topographical imaging was used to assess the surface morphology, roughness, and thickness of the dried and hydrated model cellulose film. The kinetics of the model cellulose film in the hydrated state, the adsorption of TMPAC onto the film followed by desorption given by an enzyme extracted from Trichoderma Viride were studied by in situ null ellipsometry. The results show that the adsorption of TMPAC onto model cellulose film slows down the rate of degradation, as confirmed by a slower decrease in the film mass and by different behaviour of the thickness of the film pre-treated with antimicrobial agent in comparison with pure model cellulose film.
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| 23. |
- Jiang, Nan, et al.
(author)
-
Perforated Vesicles as Intermediate Structures in the Transition from Vesicles to Micelles in Dilute Aqueous Systems Containing Long Chain Alcohols and Ionic Surfactants.
- 2009
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 30:6, s. 802-808
-
Journal article (peer-reviewed)abstract
- Morphologies of aggregates in mixtures of long chain alcohols (n-decanol, n-dodecanol, and oleyl alcohol) and cationic surfactants (cetylpyridinium chloride, cetyltrimethylammonium bromide, and chloride) in dilute aqueous salt solutions were investigated by cryogenic transmission electron microscopy. In all cases elongated micellar structures transformed into vesicles with increasing alcohol concentration. Perforated bilayer structures were clearly identified in systems with oleyl alcohol and CTAB, in particular in 0.100 M NaBr. Increasing the salt concentration to 0.200 M other aggregates dominated composed of threadlike, probably branched, and interconnected micelles. A gradual evolution of morphologies was observed with increasing alcohol content at the lower salt concentration: thread-like micelles (developing branching to some extent), perforated vesicles, coexisting perforated and smooth bilayer structures, only smooth bilayers, and finally also inverted strucutures.
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| 24. |
- Karlsson, Philip, 1977, et al.
(author)
-
Dissolution and Protection of Aluminium Oxide in Corrosive Aqueous Media – an Ellipsometry and Reflectometry Study
- 2009
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 1532-2351 .- 0193-2691. ; 30:6, s. 949-953
-
Journal article (peer-reviewed)abstract
- Dissolution of alumina has been studied from wafers in aqueous solution by means of ellipsometry and reflectometry. It was discovered that the dissolution of aluminium oxide is promoted by ethanol amines like N,N-bis(2-hydroxyethyl)glycine and triethanolamine, and that this dissolution is retarded by sodium dodecyl sulphate (SDS) and stopped by sodium dodecyl phosphate (SDP). The protective property of SDP to alumina is in perfect agreement with earlier found results which showed that SDP efficiently hinders the oxidation of aluminium pigment flakes in alkaline aqueous solution. Ethanol amines are used to regulate the pH in waterborne paints and printing ink formulations. However, the aggressive properties of ethanol amines to alumina are a problem for these kinds of formulations. This may be attributed to the formation of water soluble complexes between ethanol amines and Al(III). To increase the shelf life of aluminium pigments in waterborne formulations in the future, the ethanol amines then need to be replaced by other, less aggressive, bases if possible. © Taylor & Francis Group, LLC.
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| 25. |
- Kayali, Ibrahim, et al.
(author)
-
Alternative Diesel Fuel : Microemulsion Phase Behavior and Combustion Properties
- 2016
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 37:6, s. 894-899
-
Journal article (peer-reviewed)abstract
- The phase behavior of water, diesel, limonene, and ethanol was investigated at ambient temperature using single nonionic alkyl polyglycol ethers (C14E3). Visual inspection as well as crosspolarizers was used to detect transparency and anisotropy. Ternary phase diagrams were determined. Combustion experiments using a four-cylinder diesel engine were carried out. Isotropic water in diesel microemulsion region (L2) and anisotropic liquid crystalline region (LC) were found with all combinations. Increasing the ratio of limonene to diesel reduced the microemulsion region while the presence of ethanol increased it on the expense of the LC region. Combustion tests performed on a selected formulation from the ternary phase diagram of water, diesel, ethanol, and C14E3 revealed substantial reduction of soot, NOx, and CO2 emissions compared to neat diesel.
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| 26. |
- Kayali, Ibrahim, et al.
(author)
-
Effect of type of fragrance compounds on their location in hexagonal liquid crystal
- 2006
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 27:8, s. 1151-1155
-
Journal article (peer-reviewed)abstract
- Three fragrances, limonene, benzaldehyde, and phenethylalcohol (that differ in their polarities), were solubilized in hexagonal liquid crystal using the polyethylene oxide-polypropylene oxide-polyethylene oxide, (EO27 PO61 EO27), P-104 triblock copolymer, and water. The interlayer spacing of the hexagonal liquid crystals were established using small-angle x-ray scattering (SAXS). The SAXS data are used to calculate the interfacial area per polyethylene oxide (PEO) block and the radius of the apolar domain in order to determine the location of each fragrance in the association structure. The results show the presence of limonene inside the core of the apolar domain while benzaldehyde is only partially located inside the core with the other part contributing to the interface. The third fragrance, phenethylalcohol, is present between the polar heads, thus, contributing entirely to the interface.
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| 27. |
- Kayali, Ibrahim, et al.
(author)
-
Formulating Middle Phase Microemulsions Using Extended Anionic Surfactant Combined with Cationic Hydrotrope
- 2011
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 32:1, s. 41-46
-
Journal article (peer-reviewed)abstract
- The phase behavior of systems containing sodium alkyl polypropylene oxide sulfate with equimolar ratio of polypropylene oxide ammonium chloride was determined as a function of salt concentration and alkane carbon number at ambient temperature. Visual inspection as well as cross polarizers were used to detect anisotropy. Solubilization ratios for oil and brine in the middle phases were measured and used to calculate the interfacial tension (IFT) between the microemulsion and oil or brine. The fish diagram is presented showing a minimum amount of 0.20wt% surfactant needed to form the middle phase. Swelling increases with decreasing the alkane carbon number of the oil. Ultra low IFT values were predicted for the systems investigated.
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| 28. |
- Kayali, Ibrahim, et al.
(author)
-
Microemulsion Phase Behavior of Aerosol-OT Combined with a Cationic Hydrotrope in the Dilute Region
- 2010
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 31:2, s. 183-187
-
Journal article (peer-reviewed)abstract
- The phase behavior of systems containing minimum amounts of sodium bis (2-ethylhexyl) sulfosuccinate with equimolar ratio of tetra ethyl ammonium chloride were studied as a function of salt concentration and alkane carbon number at ambient temperature. Visual inspection as well as cross polarizers were used to detect anisotropy. Solubilization ratios for oil and brine in the middle phases were measured and used to calculate the interfacial tension. Ultra-low interfacial tension values were predicted for the systems containing heptane, octane and nonane as model oil. Different phase behavior was observed for systems with higher alkane number.
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| 29. |
- Kayali, Ibrahim, et al.
(author)
-
Phase Behavior of Bicontinuous and Water/Diesel Fuel Microemulsions Using Nonionic Surfactants Combined with Hydrophilic Alcohol Ethoxylates
- 2015
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 36:1, s. 10-17
-
Journal article (peer-reviewed)abstract
- Bicontinuous and water-in-diesel microemulsions were formulated using single nonionic alkyl poly glycol ethers combined with hydrophilic alcohol ethoxylates. The phase behavior at temperatures ranging from 0 degrees C to 50 degrees C was investigated. Visual inspection as well as cross-polarizers were used to detect anisotropy. The fish phase diagrams were determined. The presence of the hydrophilic alcohol ethoxylates was necessary to initiate both types of microemulsions. Increasing the hydrophobic chain length of the surfactant led to a wider range of temperature stability at lower surfactant concentration. Meanwhile, increasing the ethylene oxide units in the headgroup by two units led to a phase diagram that is dominated by lyotropic liquid crystal. The formulated water in diesel microemulsions were tested experimentally in a 4-cylinder diesel engine. From this it is observed that the emissions of NOx, soot, and CO2 were reduced substantially compared to neat diesel, while for the CO the reduction occurs just at low load.
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| 30. |
- Kayali, Ibrahim, et al.
(author)
-
Phase Behavior of Microemulsions Formulated with Sodium Alkyl Polypropylene Oxide Sulfate and a Cationic Hydrotrope
- 2012
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 33:1-3, s. 369-373
-
Journal article (peer-reviewed)abstract
- The partial ternary phase diagram of anionic extended surfactant of alkyl polypropylene oxide sulfate C-12(PO)(4)SO4 alone and combined with the cationic hydrotrope, tetrabutyl ammonium bromide with water and decane were determined under ambient conditions. Middle phase microemulsion was formulated using salinity scans in the dilute region of surfactant/brine/decane. Visual inspection as well as cross polarizer and optical microscopy were used to detect anisotropy. Spinning drop tensiometer was used to measure interfacial tension (IFT). The first ternary phase diagram using the extended surfactant alone showed three one phase regions; the anisotropic lamellar liquid crystalline phase, L-alpha and the isotropic L-1 micellar liquid and L-3 sponge phase. In the second ternary phase diagram using the extended surfactant combined with tetra butyl ammonium bromide, an isotropic micellar region, L-1, appeared in the diluted area of the phase diagram. Meanwhile the L-alpha phase disappeared completely and the three phase region has a bluish transparent middle phase. Interfacial tension measurements between middle phase and brine, and between decane and brine yielded ultra low values. Calculated IFT values using the characteristic length obtained using De Gennes approximation gave almost half the measured values. The interfacial rigidity was also calculated and compared to values obtained from the literature.
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| 31. |
- Kayali, Ibrahim, et al.
(author)
-
Water-Diesel Microemulsions Stabilized by an Anionic Extended Surfactant and a Cationic Hydrotrope
- 2012
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 33:4, s. 516-520
-
Journal article (peer-reviewed)abstract
- Alcohol-free microemulsions were formulated using mixtures of extended surfactant (C12-14-PO14-EO2SO4Na), sodium dodecyl benzene sulfonic acid and cationic hydrotropes with equal amounts of water and diesel. The cationic hydrotropes had short hydrocarbon or propylene oxide chain. The formulation included sodium carbonate to convert naphthenic acids in diesel to soaps. The phase behavior at ambient temperature of oil-free mixtures as a function of NaCl concentration was investigated. Visual inspection as well as cross polarizers were used to detect anisotropy. The microemulsion fish phase diagram and solubilization ratios for diesel and brine in the middle phases were determined. The minimum surfactant concentration needed to initiate middle phase formation was 0.10 wt%. Salinity scans revealed that optimal salinity can be adjusted according to the hydrophilic/lipophilic nature of the hydrotrope used. Interfacial tension measurements using a spinning drop tensiometer showed a minimum value of 0.0015 mN/m between middle phase microemulsion and excess brine and a value of 0.032 mN/m between diesel and brine.
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| 32. |
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| 33. |
- Kronberg, B, et al.
(author)
-
Understanding the hydrophobic effect
- 1994
-
In: Journal of Dispersion Science and Technology. - 0193-2691 .- 1532-2351. ; 15, s. 333-351
-
Journal article (peer-reviewed)abstract
- The hydrophobic effect is the common expression for processes where nonpolar groups in molecules are spontaneously removed from water. Thermodynamic analysis of hydrocarbon solubility in water, micellization and adsorption of surfactants show that the hydrophobic effect can be understood in terms of two contributions. The first contribution is attributed to the structuring, or rearrangement, of water molecules in the vicinity of a hydrophobe. This contribution is favorable, and hence increases the solubility of hydrocarbons in water, increases the cmc, and decreases the adsorption of surfactants. The second contribution is attributed to the formation of a cavity in the water in order to accommodate the hydrophobe. This contribution dominates over the first one and is unfavorable, i.e. it decreases the solubility of hydrocarbons in water, decreases the cmc, and increases the adsorption of surfactants. Thus, the cause of the hydrophobic effect is to be found in the large energy required to form a cavity in the water. On the other hand the temperature dependence of the hydrophobic effect is entirely determined by the water structuring, or rearrangement, in the vicinity of a hydrophobe.
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| 34. |
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| 35. |
- Lindblom, Göran, et al.
(author)
-
Order and Disorder in a Liquid Crystalline Bilayer: Pulsed Field Gradient NMR Studies of Lateral Phase Separation
- 2007
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 28, s. 55-61
-
Journal article (peer-reviewed)abstract
- The pulsed field gradient NMR method utilized for determination of lipid lateral diffusion in macroscopically aligned lipid bilayers is described. This technique is proposed to have an appreciable potential for biophysical investigations in the field of lipid (lipidomics) and membrane biology. Topics like transport of molecules both across and in the plane of the membrane can be studied successfully, as well as the formation of lipid domains and their intrinsic dynamics can be scrutinized. In this review some recent results on lipid membrane systems are presented. In particular investigations, not easily monitored with other spectroscopic methods, of so-called "raft membranes" are presented. In these membranes two-phase coexistence between liquid disordered (ld) and liquid ordered (lo) phases occurs. Methods for obtaining good oriented lipid membranes, necessary for the NMR method to be efficiently used, are also described. Quite unexpectedly, cholesterol (CHOL) seems to partition into both phases to roughly the same extent, indicating that CHOL has no particular preference for any of the ld and lo phases, and that there are no specific interactions between CHOL and saturated lipids. Another interesting observation is that the lateral diffusion is the same for all components, independent of the molecular structure (thus including CHOL), if they reside in the same domain in the membrane.Furthermore, it is found that the domain formation process is sensitive to small changes in the phospholipid chain composition and the structure of the sterol. However, more studies are needed to explain the effect on the raft-forming properties from changes in the positions and the number of double bonds in the sterol ring system.
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| 36. |
- Lindman, Björn
(author)
-
Per Ekwall and Physical Chemistry 1 in Lund: Ion binding and microstructure in relation to phase behavior
- 2007
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 28:1, s. 21-29
-
Journal article (peer-reviewed)abstract
- The research in the Department of Physical Chemistry 1 at Lund University includes topics such as surfactant self-assembly; polymers, solutions, gels and phase behavior, polymer-surfactant systems; protein and protein-amphiphile systems; adsorption and surface forces; experimental methodology in colloid science; and theory and modeling. (Annual Report (2004) Physical Chemistry 1; Lund University; Sweden.) How different research topics emerge is, of course, in many cases a complicated story and there are often long traces back. In this treatise, looking back on connections, we will demonstrate that early contacts with Per Ekwall have to a considerable extent influenced our research directions. As we will describe, the early contacts concerned experimental studies of ion binding in concentrated surfactant systems. These inspired further studies of ion binding in a range of colloid systems and these, in turn, theoretical work on electrostatic interactions. Per Ekwall and his coworker Krister Fontell also introduced us into the fascinating subject of cubic liquid crystals, which inspired us into the problem of connectivity versus discreteness of surfactant self-assemblies. Another significant aspect of the contacts with Per Ekwall and his group was that we learned the important role of phase diagrams in understanding surfactant systems. After analyzing briefly the early contacts we will exemplify some of our work on ion binding and on microstructure; aspects on phase diagrams are discussed by Hakan Wennerstrom in another article in this volume.
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| 37. |
- Lindström, A, et al.
(author)
-
Interactions in phospholipid stabilized emulsion system
- 1999
-
In: Journal of Dispersion Science and Technology. - 0193-2691 .- 1532-2351. ; 20, s. 247-256
-
Journal article (peer-reviewed)abstract
- The interaction between a phospholipid stabilized triglyceride emulsion and a hydrophilic silica surface has been studied at varying pH and electrolyte content using ellipsometry. The adsorbed amount decreases with pH and increases with increasing electrolyte content in the emulsion, and this can be rationalized on the basis of the electrostatic interaction between the emulsion droplet and the surface. The layer thickness, however, is essentially independent of these parameters. In addition, the emulsion has been studied during turbulent shear conditions (applied mechanical stress), with the same variation of pH and electrolyte as in the adsorption experiments. A decrease in pH and an increase in electrolyte content, decreasing the repulsive interaction between the droplets, leads to a deterioration in emulsion stability with time.
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| 38. |
- Lundberg, Dan, 1975, et al.
(author)
-
Studies on the Interactions Between Mucin and Surfactant Aggregates Containing the Cationic Surfactant Dodecyl Betainate
- 2009
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 1532-2351 .- 0193-2691. ; 30:6, s. 920-928
-
Journal article (peer-reviewed)abstract
- The interactions of surfactant aggregates containing the cationic, cleavable surfactant dodecyl betainate (DB) with mucin are investigated. The aggregates were either mixed micelles of DB and the nonionic surfactant PS-80 in different ratios or a dispersion of the commercial self-emulsifying drug-delivery formulation Sandimmun Neoral charged with DB. It is found that for the surfactant aggregates to show any notable interactions with mucin these must have a high positive charge density. Also presented are results from Ussing chamber experiments, which suggest that DB has a limited impact on the integrity and the barrier function of the intestinal epithelium.
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| 39. |
- Malmsten, Martin, et al.
(author)
-
Ellipsometry studies of lipoprotein adsorption as a biosensor tool in atherosclerosis
- 2009
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 30:6, s. 795-801
-
Journal article (peer-reviewed)abstract
- Lipoprotein adsorption was investigated at a range of surfaces by in situ ellipsometry, with the aim of reaching a better understanding of its possibilities and limitations as a biosensor tool in the context of atherosclerosis. Although ellipsometry allows direct investigation of lipoprotein interfacial deposition at surfaces coated with confluent layers of endothelial cells, that is, essentially the full biological system equivalent, a simpler and more robust model system based on proteoheparan sulfate adsorbed via its membrane-anchoring domain at hydrophobic surfaces was found to provide largely the same information. While simplistic, it was found that Ca2+-induced adsorption of a range of lipoproteins involved in atherosclerosis at surfaces coated with proteoheparan sulfate indeed provides some accelerated information on initial atherosclerotic plaque formation, as evidenced by correlations between lipoprotein adsorption and well known clinical effects of lipoprotein composition and of treatment with anti-atherosclerotic drugs of synthetic as well as natural origin.
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| 40. |
- Malmsten, Martin
(author)
-
Phase transformations in self-assembly systems for drug delivery applications
- 2007
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 28:1, s. 63-72
-
Journal article (peer-reviewed)abstract
- This brief review aims at providing some illustrative examples on the use of self-assembly structures formed by surfactants, (polar) lipids, and (block) copolymers in drug delivery, with particular focus placed on how phase transformations in such systems may offer functional opportunities in relation to drug administration.
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| 41. |
- Momekova, Denitsa, et al.
(author)
-
Effects of Amphiphilic Copolymers Bearing Short Blocks of Lipid-Mimetic Units on the Membrane Properties and Morphology of DSPC Liposomes
- 2008
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 29:8, s. 1106-1113
-
Journal article (peer-reviewed)abstract
- Amphiphilic, nonionic diblock copolymers based on poly(ethylene glycol) (PEG 2000-5000), comprising short blocks of lipid-mimetic units, where tested for their ability to afford steric stabilization of distearoylphosphathydilcholine:cholesterol liposomes. The copolymers bear 1-4 lipid-mimetic anchors per copolymer chain. Effects on liposomes size depend on copolymer type and content. Cryo-TEM reveals well-sepd., intact, predominantly spherical liposomes at copolymer contents up to 5 mol%. A "flat" liposomes fraction occurs upon incorporation of above 7.5 mol% of copolymers bearing 2 or 4 lipid anchors. 5,6-carboxyfluorescein assay indicates lower leakage of stabilized vs. plain liposomes up to concn. 7.5 mol%. Leakage from liposomes with higher copolymer concn. is insignificantly greater.
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| 42. |
- Moran, M. C., et al.
(author)
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Chitosan-DNA Particles for DNA Delivery: Effect of Chitosan Molecular Weight on Formation and Release Characteristics
- 2009
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 30:10, s. 1494-1499
-
Journal article (peer-reviewed)abstract
- Novel DNA-chitosan particles were prepared based on associative phase separation and interfacial diffusion. These particles formed at water/water emulsion type interfaces were characterized with respect to several properties including stability, DNA conformational state, and entrapment and release of DNA. In particular it was found that the chitosan molecular weight is a good controlling parameter.
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| 43. |
- Munavirov, Bulat V., et al.
(author)
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Polyacrylic Acid Modifies Local and Lateral Mobilities in Lipid Membranes
- 2014
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 35:6, s. 848-858
-
Journal article (peer-reviewed)abstract
- Polyacrylic acid (PAA) is a promising polymer for engineering lipid-based drug-delivery vesicles. Its unique properties allow lowering drug dose and delivery the drug close to the site of its release. To design a successful delivery scheme, however, it is important to understand on the molecular scale how the polymer interacts with lipids under various conditions in the human body. Some aspects of the PAA-lipid interaction can be revealed using physical methods, such as differential scanning microscopy, nuclear magnetic resonance spectroscopy, NMR-diffusometry, and infrared spectroscopy. This work discusses the use of these techniques as well as the peculiarities of preparing vesicular and microscopically aligned PAA-lipid systems.
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| 44. |
- Naderi, Ali, et al.
(author)
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Association between poly(vinylamine) and sodium dodecyl sulfate : Effects of mixing protocol, blending procedure, and salt concentration
- 2005
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 26:3, s. 329-340
-
Journal article (peer-reviewed)abstract
- The association between a weak cationic linear polyelectrolyte, poly(vinylamine), and the anionic surfactant sodium dodecyl sulfate (SDS) has been investigated in dilute solutions, containing 20 ppm of poly(vinylamine) and surfactant up to a concentration of 8 mM. We particularly focus on the importance of the order of addition of the components and of stirring after mixing. Two mixing protocols were used, denoted PTS and STP. In the PTS method the polyelectrolyte is added to the surfactant solution, and in the STP method the surfactant is added into the polyelectrolyte solution. The results obtained demonstrate the presence of long-lived trapped nonequilibrium states. In addition, we also address the effect of the blending procedure on association. We studied two blending methods, denoted Blending and Vigorous Blending. In the Blending method equal volumes of the polyelectrolyte and surfactant were added simultaneously to the sample tube, after which the ingredients were mixed together by turning the sample tube upside down a few times; in the Vigorous Blending method the mixing was provided by a magnetic stirrer. The results, obtained using turbidity, electrophoretic mobility, and light scattering measurements, demonstrate that Vigorous Blending facilitates flocculation at low SDS concentrations, close to the charge neutralization concentration of the system. This is interpreted as being due to additional surfactant incorporation in initially positively charged complexes during collision events. Vigorous mixing in excess surfactant produces stable dispersions consisting of small negatively charged complexes containing one polyelectrolyte and surfactant in excess of what is needed to neutralize the polyelectrolyte charges. The same results are obtained with the Blending protocol, which gives comparable particle size and polydispersity in excess surfactant and polyelectrolyte.
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| 45. |
- Nordstierna, Lars, 1976, et al.
(author)
-
New Route for Microcapsule Synthesis
- 2011
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 1532-2351 .- 0193-2691. ; 32:3, s. 310-311
-
Journal article (peer-reviewed)abstract
- Studies on the growth of microorganisms on painted surfaces and other coatings has increased during the last decades as many antigrowth agents have gradually been prohibited due to toxicity. Current applications using biocides lose the protection quite rapidly as small molecular size renders a fast diffusional biocide leakage. A promising improvement of antigrowth protection can be achieved by the use of encapsulated biocides in the paint. The candidate method to produce microcapsules has dichloromethane as a key constituent in the synthesis step.[3] Dichloromethane is hazardous and thereby often not allowed to be used at industrial scale. In this article, we show that ethyl acetate has equivalent physiochemical properties as dichloromethane in the production of microcapsules and thus can be used in order to fulfill legislative criteria.
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| 46. |
- Panek, Jiri, et al.
(author)
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Polymeric Nanoparticles Stabilized by Surfactants Investigated by Light Scattering, Small-Angle Neutron Scattering, and Cryo-TEM Methods
- 2011
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 32:6, s. 888-897
-
Journal article (peer-reviewed)abstract
- We have investigated self-organization of polymers with surfactants through solvent shifting process resulting in formation of stable and uniform nanoparticles. We studied polymeric nanoparticles made of poly(methylmethacrylate) and of polystyrene dispersed in water. The dispersion was prepared by a fast mixing of a solution of the polymers with a solution of several ionic and nonionic surfactants in pure water. We observed the formation of well defined nanoparticles by light scattering, small-angle neutron scattering (SANS), and cryogenic transmission electron microscopy (Cryo-TEM) methods. The study shows how nanoparticle properties are changed by the chemical composition of surfactants, molar mass of polymers, concentrations of both components and finally, by variations in method of nanoparticles preparation. Dynamic light scattering (DLS) and static light scattering (SLS) provide the hydrodynamic radii and radii of gyration for selected types of nanoparticles. Cryo-TEM experiments prove that the nanoparticles have good spherical shape. Analysis of SANS data and Cryo-TEM micrographs suggest that the prepared particles are composed of polymer and surfactant that are evenly distributed.
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| 47. |
- Patra, Anuttam, et al.
(author)
-
Selective flotation of calcium minerals using double-headed collectors
- 2019
-
In: Journal of Dispersion Science and Technology. - : Taylor & Francis. - 0193-2691 .- 1532-2351. ; 40:8, s. 1205-1216
-
Journal article (peer-reviewed)abstract
- A study was performed involving a series of double-headed carboxylate collectors with varying distance between the head groups (one, two or three carbon atoms). A collector with the same alkyl chain length but with only one carboxylate group was also included. All these were amino-acid based amphiphiles and the polar head group was connected to the hydrophobic tail via an amide linkage. Selective flotation recovery of different calcium minerals using these collectors was investigated. The double-headed collector with one carbon atom between the carboxylate groups was an apatite and fluorite specific reagent while the monocarboxylate surfactant showed high specificity for calcite. The flotation behavior of a simple conventional collector of the same alkyl chain length, a fatty acid salt, was also determined under identical flotation conditions in order to understand the effect of the amide group. Complementary experiments (ζ potential measurements, adsorption isotherm determinations) were also performed for these reagents. In order to shed light on the selectivity obtained with the dicarboxylate surfactants, the distances between the head groups were calculated and compared with the distances between neighboring calcium atoms on the surface of the minerals. It was found that the high degree of selectivity could be rationalized by perfect matching of these distances. To the best of our knowledge this is the first study where flotation selectivity in complex calcium mineral systems has been explained in terms of molecular recognition governing the interaction between the collector and the mineral surface.
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| 48. |
- Pihl, Maria, 1978, et al.
(author)
-
Silica-based diffusion probes for use in FRAP and NMR-diffusometry
- 2019
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 40:4, s. 555-562
-
Journal article (peer-reviewed)abstract
- Development of multi-purpose probes for mass transport measurements is of importance to gain knowledge in diffusional behaviour in heterogeneous structures such as food, hygiene or pharamceuticals. By combining different techniques, such as Fluorescence Recovery After Photobleaching (FRAP) and Nuclear Magnetic Resonance Diffusometry (NMR-d), information of both local and global diffusion can be collected and used to gain insights on for example material heterogeneities and probe-material interactions. To obtain a FRAP-responsive probe, fluorescent silica particles were produced using fluorescent preconjugates added in a modified Stöber process. A NMR-d responsive moiety was introduced by derivatizing the fluorescent silica particles with polyethylene glycol. The particle size distributions were determined by dynamic light scattering and transmission electron microscopy and these measurements were compared to value extrapolated from diffusion measurements using FRAP and NMR-d. The good agreement between the FRAP and NMR-d measurements demonstrates the potential of multi-purpose probes for future applications concerning mass transport at local and global scale simultaneously. © 2018, © 2018 The Author(s).
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| 49. |
- Rippner Blomqvist, Brita, et al.
(author)
-
Competitive destabilization/stabilization of beta-lactoglobulin foam by PEO-PPO-PEO polymeric surfactants
- 2006
-
In: Journal of Dispersion Science and Technology. - : Informa UK Limited. - 0193-2691 .- 1532-2351. ; 27:4, s. 527-536
-
Journal article (peer-reviewed)abstract
- The effect on ss-lactoglobulin foamability and foam stability of the poly(ethylene oxide)-poly(propylene oxide) block copolymers F127 (PEO99-PPO65-PEO99), molecular weight 12500 g/mol, and P85 (PEO26-PPO39-PEO26), molecular weight 4600 g/mol, has been investigated at constant protein concentration, 10 mu M (0.2 mg/L), and varying block copolymer concentrations, ranging from 0.02 to 1600 mu M. Foam was generated by means of air sparging and the foam volume and liquid volume of the foam were measured for one hour. It was found that foam stabilized by F127 or P85 in the concentration range 20-1600 mu M contained a larger liquid volume initially than pure ss-lactoglobulin foam. Furthermore, ss-lactoglobulin foamability was only marginally affected by the presence of F127, while it was reduced in an interval of low P85 concentrations. The protein foam stability was retained in the presence of the larger polymer F127, whereas P85 largely reduced the stability, indicating that the size of the polymeric surfactant is important. The results are discussed in relation to surface rheological properties and forces acting across foam films. Steric repulsion generated between the surfaces of foam films is suggested to be the main stabilizing factor in dry foam containing F127. The instability of the mixed ss-lactoglobulin/P85 system is suggested to be caused by two effects. First, there are incompatible stabilization mechanisms of block copolymer and protein, as supported by previous surface rheological data. Second, there is a reduced importance of long-range steric repulsion when P85 is added, compared to the case where F127 and ss-lactoglobulin are mixed.
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| 50. |
- Rippner Blomqvist, B, et al.
(author)
-
Competitive destabilization/stabilization of β-lactoglobulin foam by PEO-PPO-PEO polymeric surfactants
- 2006
-
In: Journal of Dispersion Science and Technology. - 0193-2691 .- 1532-2351. ; 27:4, s. 527-536
-
Journal article (peer-reviewed)abstract
- The effect on .beta.-lactoglobulin foam-ability and foam stability of the poly(ethylene oxide)-poly(propylene oxide) block copolymers F127 (PEO99-PPO65-PEO99), mol. wt. 12500 g/mol, and P85 (PEO26-PPO39-PEO26), mol. wt. 4600 g/mol, has been investigated at const. protein concn., 10 .mu.M (0.2 mg/L), and varying block copolymer concns., ranging from 0.02 to 1600 .mu.M. Foam was generated by means of air sparging and the foam vol. and liq. vol. of the foam were measured for one hour. It was found that foam stabilized by F127 or P85 in the concn. range 20-1600 .mu.M contained a larger liq. vol. initially than pure ss-lactoglobulin foam. Furthermore, ss-lactoglobulin foam-ability was only marginally affected by the presence of F127, while it was reduced in an interval of low P85 concns. The protein foam stability was retained in the presence of the larger polymer F127, whereas P85 largely reduced the stability, indicating that the size of the polymeric surfactant is important. The results are discussed in relation to surface rheol. properties and forces acting across foam films. Steric repulsion generated between the surfaces of foam films is suggested to be the main stabilizing factor in dry foam contg. F127. The instability of the mixed ss-lactoglobulin/P85 system is suggested to be caused by two effects. First, there are incompatible stabilization mechanisms of block copolymer and protein, as supported by previous surface rheol. data. Second, there is a reduced importance of long-range steric repulsion when P85 is added, compared to the case where F127 and ss-lactoglobulin are mixed.
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