This paper describes a new method for forming micron-and submicron-scale patterns of copper on surfaces. This method uses microcontact printing (µCP) to deposit colloids that serve as catalysts for the selective electroless deposition of copper. A patterned elastomeric stamp fabricated from poly-(dimethylsiloxane) was used to deliver the catalystspalladium colloids stabilized with tetraalkylammonium bromidessto the substrate surface. The electroless deposition of the copper on the sample occurred only where palladium colloid was transferred to the substrate. Electroless deposition catalyzed by the colloids resulted in the formation of metal structures with features having submicron dimensions, with an edge resolution in the range of 100 nm. This technique of activating substrates for electroless metalization was successfully used to pattern glass, (Si/SiO 2), and polymers; both flat and curved substrates were used. Microcontact printing of colloids was also used to fabricate metal structures whose thicknesses were varied in different regions of the sample (multilevel metal structures). Free-standing metal structures were produced by dissolving the substrate after the metal film had reached the desired thickness.

The interaction between citric acid and alumina in aqueous solution is characterized. Adsorption isotherms of the dispersant on the alumina surface, electrophoretic mobility of the alumina particles as a function of the citric acid concentration, and attenuated total reflection Fourier transform infrared (ATR‐FTIR) spectroscopy of the citratealumina surface complex have been used. The adsorption behavior of citric acid is dependent on the pH of the suspension and the concentration of the citric acid. The maximum amount of citric acid adsorbed on the alumina surface, 2.17 μ.mol/m2 at pH 3, decreases to 1.17 μmol/m2 at pH 8. The adsorption of citrate causes a highly negatively charged powder surface and a shift of the isoelectric point (IEP) to lower pH values. The IEP of alumina can be fixed at any pH value between 9 and 3 by proper adjustment of the citric acid concentration. In situ ATR‐FTIR spectroscopy of the citrate‐alumina surface complex gives evidence for a direct interaction between the carboxylate groups of the citrate and the surface aluminum(III) atoms. The rheological properties of alumina suspensions are studied as a function of the citric acid concentration. The data obtained from the viscosity and dynamic electrophoretic measurements correlate well and allow the construction of a stability map of alumina suspensions stabilized with citric acid. The influence of citric acid on the viscosity is discussed using the Derjaguin‐Landau‐Verwey‐Overbeek (DLVO) theory. The interaction potential between the particles is determined by the citrate adsorbed on the surface, leading to a negative particle charge, and the citrate anions remaining in the solution, resulting in an increase of the ionic strength. The adsorption of citric acid also creates a steric barrier that inhibits the complete mutual approach of the individual alumina particles.

Organic molecules, such as pharmaceuticals, agro-chemicals and pigments, frequently form several crystal polymorphs with different physicochemical properties. Finding polymorphs has long been a purely experimental game of trial-and-error. Here we utilize in silico polymorph screening in combination with rationally planned crystallization experiments to study the polymorphism of the pharmaceutical compound Dalcetrapib, with 10 torsional degrees of freedom one of the most flexible molecules ever studied computationally. The experimental crystal polymorphs are found at the bottom of the calculated lattice energy landscape, and two predicted structures are identified as candidates for a missing, thermodynamically more stable polymorph. Pressure-dependent stability calculations suggested high pressure as a means to bring these polymorphs into existence. Subsequently, one of them could indeed be crystallized in the 0.02 to 0.50 GPa pressure range and was found to be metastable at ambient pressure, effectively derisking the appearance of a more stable polymorph during late-stage development of Dalcetrapib.

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This paper describes a new method of reducing the size of the metal features made by electroless deposition and fabricating complex-shaped, patterned surfaces. Microcontact printing (µCP) was used to pattern oriented glassy polymers with palladium colloids, stabilized with tetraoctadecylammonium bromide. These colloids are catalysts for the selective electroless deposition of copper. Annealing of the activated polymer at a temperature slightly above its glass transition temperature led to a shrinkage of the substrate. Immersion of the shrunken substrate in the plating bath yielded the metal features. The maximum shrinkage of the feature size achieved was on the order of a factor of ∼4 in one direction of the oriented polymer and of ∼7 in the perpendicular direction. Control of the extent and direction of shrinkage allowed the fabrication of metal features with sizes and shapes different from those on the polydimethylsiloxane stamp used for the patterning of the substrate and from the draw ratios. Free-standing metal structures were produced by dissolving the substrate after the metal film had reached the desired thickness. Complexshaped, patterned surfaces could be fabricated by wrapping the activated polymer film around a scaffolding or template; during the annealing, the polymer adapted the shape of the underlying scaffolding. Metalization of the activated, shaped substrate resulted in patterned three-dimensional structures.

International audienceThis paper demonstrates the use of microcontact printing (μCP) and capillary filling (CF) to pattern the deposition of iron oxides on a surface with feature sizes of microns. Selective wetting of both self-assembled monolayers (SAMs) of alkanethiolates on gold and alkylsiloxanes on Si/SiO2 formed by microcontact printing limited the deposition of the iron oxides to the hydrophilic areas on the surfaces; thereby, the chemical functionality of the hydrophilic SAM had only a minor influence on the wetting behavior and the deposition. The iron oxides were deposited either as magnetite particles from colloidal solution, by precipitation of the oxide from previously deposited drops of water containing an iron(III) salt, or by ferrite plating. The size of the metal oxide patterns was limited to the size of the areas that could be patterned using μCP. Capillary filling using a colloidal solution of magnetite could also be used to fabricate continuous, interconnected structures of magnetite. The magnetic properties of the deposited iron oxides were characterized by magnetic force measurement (MFM) and by measurement of the magnetization. The magnetite particles deposited in these experiments showed superparamagnetic behavior; they were too small individually to support a permanent magnetization

The X‐ray structures of fifteen 1, 3‐imidazolidine, 1, 3‐oxazolidine, 1, 3‐dioxan‐4‐one, and hydropyrimidine‐4(1H)‐one derivatives are described (Table 2) and compared with known structures of similar compounds (Figs. 1–20). The differences between structures containing exocyclic N‐acyl groups and those lacking this structural element arise from the A1,3 effect of the amide moieties. Even t‐Bu groups are forced into axial positions of six‐ring half‐chair or into flag‐pole positions of six‐ring twist‐boat conformers by this effect (Figs. 16–20). In the N‐acylated five‐membered heterocycles, a combination of ring strain and A1, 3 strain leads to strong pyramidalizations of the amide N‐atoms (Table 1) such that the acyl groups wind up on one side and the other substituents on the opposite side of the rings (Figs. 4–9 and Scheme 3). Thus, the acyl (protecting!) groups strongly contribute to the steric bias between the two faces of the rings. Observed, at first glance surprizing stereoselectivities of reactions of these heterocycles (Schemes 1 and 2) are interpreted (Scheme 3) as an indirect consequence of the amide A1, 3 strain effect. The conclusions drawn are considered relvant for a better understanding of the ever increasing role which amide groups play in stereoselective syntheses.

Poly(viny1 alcohol) (PVA) and citric acid (CA) are a commonly used binder and dispersant, respectively, for aqueous Al,O, slurries. The competitive adsorption of these additives on A1,0, from aqueous solution was studied, as was the influence of this competition on the binder migration in centrifugally cast compacts during the drying process. PVA did not influence the adsorption behavior of CA. However, the adsorption of PVA on cu-Al,O, was strongly reduced by the presence of CA. This displacement of PVA by CA led to a drastically increased segregation of PVA during the drying process.