Stockholm, Sweden

The Institute for Surface Chemistry, YKI is an industrial research institute in applied surface and colloid chemistry located in Stockholm, Sweden. It is located on the campus of the Royal Institute of Technology . YKI's mission is to transfer and develop innovations to customers in industrial sectors where surface chemistry plays an important role. The areas of expertise lie in the fields of surface and colloid science. It has a staff of approximately 65 persons.YKI is a part of the SP Group, SP Technical Research Institute of Sweden. The work within YKI is organized in three sections, Materials and Coatings Section, Forest Products Section and Life Science and Chemical Industries Section. Wikipedia.

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Zhu Y.,KTH Royal Institute of Technology | Olofsson U.,KTH Royal Institute of Technology | Persson K.,Swedish Institute for Surface Chemistry
Wear | Year: 2012

Adhesion in the wheel-rail contact is a key factor determining stable running conditions and safety during train driving and braking. This paper presents an experiment performed in a mini-traction machine to simulate the problems of low adhesion in the wheel-rail contact. Tests were conducted under dry conditions and using water or oil as lubricants to study the influence of surface roughness on the adhesion coefficient. The results indicate that the adhesion coefficient can be reduced to as low as 0.02 for smooth surfaces lubricated with water. For rougher contact surfaces, the water-lubricated tests indicate a higher adhesion coefficient than do oil-lubricated ones, but also a clear dependence on water temperature. The oil-lubricated tests indicate a very slight dependence of the adhesion coefficient on variation in rolling speed, temperature, and surface roughness. © 2012 Elsevier B.V.

Jan Christer Eriksson and Anatoly I. Rusanov critically analyze a paper titled 'Incompatibility of the Shuttleworth equation with Hermann's mathematical structure of thermodynamics' by D. J. Bottomley and co-researchers. According to him, the problem of double counting that Bottomley and co-researchers supposed to be due to involving pairs of terms of the kind xdy + ydx, is not a true research issue but rather a pedagogical one. Within the formal scheme adopted by Gibbs, this problem is properly dealt with by means of a Gibbs Duhem condition. The critics underline that the incompatibility with the mathematical structure of thermodynamics erroneously claimed by Bottomley and co-researchers would apply not just to solid but to liquid interfaces as well, thus invalidating even the firmly rooted Gibbs surface tension equation.

Sweeney J.,University of Newcastle | Hausen F.,Leibniz Institute for New Materials | Hayes R.,University of Newcastle | Webber G.B.,University of Newcastle | And 4 more authors.
Physical Review Letters | Year: 2012

The lubricating properties of an ionic liquid on gold surfaces can be controlled through application of an electric potential to the sliding contact. A nanotribology approach has been used to study the frictional behavior of 1-butyl-1-methylpyrrolidinium tris(penta-uoroethyl) tri-uorophosphate ([Py 1,4]FAP) confined between silica colloid probes or sharp silica tips and a Au(111) substrate using atomic force microscopy. Friction forces vary with potential because the composition of a confined ion layer between the two surfaces changes from cation-enriched (at negative potentials) to anion-enriched (at positive potentials). This offers a new approach to tuning frictional forces reversibly at the molecular level without changing the substrates, employing a self-replenishing boundary lubricant of low vapor pressure. © 2012 American Physical Society.

Li H.,University of Newcastle | Rutland M.W.,Swedish Institute for Surface Chemistry | Rutland M.W.,SP Technical Research Institute of Sweden | Atkin R.,University of Newcastle
Physical Chemistry Chemical Physics | Year: 2013

Colloid probe atomic force microscopy (AFM) has been employed to investigate the nanotribology of the ionic liquid (IL)-Au(111) interface. Data is presented for four ILs, 1-ethyl-3-methylimidazolium tris(pentafluoroethyl) trifluorophosphate ([EMIM] FAP), 1-butyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([BMIM] FAP), 1-hexyl-3- methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([HMIM] FAP) and 1-butyl-3-methylimidazolium iodide ([BMIM] I), at different Au(111) surface potentials. Lateral forces vary as a function of applied surface potential and ion structure because the composition of the confined ion layer changes from cation-enriched (at negative potentials) to mixed (at 0 V), and to anion-enriched (at positive potentials). ILs with FAP- anions all exhibit similar nanotribology: low friction at negative potentials and higher friction at positive potentials. [BMIM] I displays the opposite behaviour, as an I- anion-enriched layer is more lubricating than either the [BMIM]+ or FAP- layers. The effect of cation charged group (charge-delocalised versus charged-localised) was investigated by comparing [BMIM] FAP with 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl) trifluorophosphate ([Py1,4] FAP). [BMIM] FAP is less lubricating at negative potentials, but more lubricating at positive potentials. This indicated that even at positive potentials the cation concentration in the boundary layer is sufficiently high to influence lubricity. The influence of sliding velocity on lateral force was investigated for the [EMIM] FAP-Au(111) system. At neutral potentials the behaviour is consistent with a discontinuous sliding process. When a positive or negative potential bias is applied, this effect is less pronounced as the colloid probe slides along a better defined ion plane. This journal is © the Owner Societies 2013.

Mille C.,Swedish Institute for Surface Chemistry | Mille C.,University of Stockholm | Tyrode E.C.,Swedish Institute for Surface Chemistry | Corkery R.W.,Swedish Institute for Surface Chemistry | Corkery R.W.,University of Stockholm
Chemical Communications | Year: 2011

Three dimensional silica photonic crystals with the gyroid minimal surface structure have been synthesized. The butterfly Callophrys rubi was used as a biotemplate. This material represents a significant addition to the small family of synthetic bicontinuous photonic crystals. © 2011 The Royal Society of Chemistry.

Feldoto Z.,Swedish Institute for Surface Chemistry | Varga I.,Eötvös Loránd University | Blomberg E.,Swedish Institute for Surface Chemistry
Langmuir | Year: 2010

A quartz crystal microbalance (QCM) and dual polarization interferometry (DPI) have been utilized to study how the structure of poly(allylamine hydrochloride) (PAH)/poly(styrene sulfonate) (PSS) multilayers is affected by the rinsing method (i.e., the termination of polyelectrolyte adsorption). The effect of the type of counterions used in the deposition solution was also investigated, and the polyelectrolyte multilayers were formed in a 0.5 M electrolyte solution (NaCl and KBr). From the measurements, it was observed that thicker layers were obtained when using KBr in the deposition solution than when using NaCl. Three different rinsing protocols have been studied: (i) the same electrolyte solution as used during multilayer formation, (ii) pure water, and (iii) first a salt solution (0.5 M) and then pure water. When the multilayer with PAH as the outermost layer was exposed to pure water, an interesting phenomenon was discovered: a large change in the energy dissipation was measured with the QCM. This could be attributed to the swelling of the layer, and from both QCM and DPI it is obvious that only the outermost PAH layer swells (to a thickness of 25-30 nm) because of a decrease in ionic strength and hence an increase in intra-and interchain repulsion, whereas the underlying layers retain a very rigid and compact structure with a low water content. Interestingly, the outermost PAH layer seems to obtain very similar thicknesses in water independent of the electrolyte used for the multilayer buildup. Another interesting aspect was that the measured thickness with the DPI evaluated by a single-layer model did not correlate with the estimated thickness from the model calculations performed on the QCM-D data. Thus, we applied a two-layer model to evaluate the DPI data and the results were in excellent agreement with the QCM-D results. To our knowledge, this evaluation of DPI data has not been done previously. © 2010 American Chemical Society.

Linse P.,Lund University | Claesson P.M.,Swedish Institute for Surface Chemistry
Macromolecules | Year: 2010

Adsorption of a series of charged bottle-brush polymers with side chains of different length on solid surfaces is modeled using a lattice mean-field theory. The bottle-brush polymers are modeled as being composed of two types of main-chain segments: charged segments and uncharged segments with an attached side chain. The composition variable X denotes the percentage of charged main-chain segments and ranges from X=0 (uncharged bottle-brush polymer) to X = 100 (linear polyelectrolyte). Two types of surfaces are considered: mica-like and silica-like. The mica-like surface possesses a constant negative surface charge density and no nonelectrostatic affinity for either main-chain or side-chain segments, whereas the silica-like surface has a constant negative surface potential and a positive affinity for the side chains of the bottle-brush polymers. With the mica-like surface, at low X the surface excess becomes smaller and at X > 25 it becomes larger with increasing side-chain length. Hence, the value of X at which the surface excess displays a maximum increases with the side-chain length. However, with the silica-like surface the surface excess increases with increasing side-chain length at all X < 100, and the maximum of the surface excess appears at X ≈ 10 independent of the side-chain length © 2010 American Chemical Society.

Kjellin M.,Swedish Institute for Surface Chemistry
Tenside, Surfactants, Detergents | Year: 2012

This review article will give a broad overview of the synthesized and characterised surfactants within the competence centre SNAP (Centre for Surfactants Based on Natural Products). The surfactants differ within their hydrophilic groups, hydrophobic groups as well as the linkage between these groups. The main focus was put on sugar-based surfactants and surfactants containing polyhydroxyl groups so this part will be the most extensive in the review. Interactions between surfactants and polymers have also been investigated and will be described in the final part of the review. SNAP resulted in the publication of 239 scientific articles and 22 PhD degrees. © Carl Hanser Publisher, Munich.

Dedinaite A.,Swedish Institute for Surface Chemistry
Soft Matter | Year: 2012

The lubrication of synovial joints is extremely efficient, allowing smooth motion to be performed between relatively soft and vulnerable cartilage surfaces for close to 100 years. A failure of this system leads to significant pain and loss of life quality. The ultrastructure of cartilage is complex and of functional significance. The molecules that are involved in the lubrication process are of many types, and they associate with each other in a complex fashion. This review focuses on the lubricating molecules, both biolubricants and biomimetic ones that share some features of the biolubricants. It discusses the conditions that must be fulfilled for achieving low friction in aqueous media and emphasizes the importance of load bearing capacity and self-healing ability.

Lundin M.,Swedish Institute for Surface Chemistry | Blomberg E.,Swedish Institute for Surface Chemistry | Tilton R.D.,Carnegie Mellon University
Langmuir | Year: 2010

The layer-by-layer deposition method has been used to build a multilayer thin film with two polysaccharides, chitosan CH (weak, polycation) and heparin HEP (strong polyanion), on planar quartz surfaces. The film structure and dynamics in aqueous solution were studied with fluorescence resonance energy transfer (FRET) and total internal reflection fluorescence (TIRF). Particular emphasis was placed on the effect of deposition conditions, i.e., pH and salt concentration, on the out-of-plane (vertical) diffusion of fluorescence labeled chitosan in the chitosan/heparin (CH/ HEP) film. FRET analysis showed that CH molecules diffused within the film with, a diffusion coefficient that was not significantly sensitive to the deposition p.H and solution ionic strength. A p.H-sensitive label bound to CH embedded within the CH/HEP film was sensitive to the charge of the outermost polymer layer even when buried under 14 alternate layers of CH and HEP. A consideration of the results obtained with both fluorescence techniques showed that the structure of the CH/HEP thin film was highly interpenetrated without clear boundaries between each, layer. These results are consistent with the hypothesis that the previously observed exponential-like film growth of CH and. HEP in terms of layer thickness and deposited amount versus deposition cycle can be attributed to out-of-plane diffusion of CH molecules in the multilayer. © 2009 American Chemical Society.

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