From compressibility to structural investigation of sodium dodecyl sulphate — Part 1: Powder and tablet physico-chemical characteristics

As a part of a study on detergent tablets, investigations were carried out to elucidate the compression behavior of a powdered surfactant, sodium dodecyl sulphate (SDS), based on a comparison with the main component of the formulation, i.e. the chorine provider (DCCNa). The compacted SDS exhibited poor cohesion as well as delayed dissolution whatever the compression pressure. The microscopic observations and the mercury porosimetry measurements both demonstrated that a residual porosity existed in the tablets but the dissolution times were always long. A modification of SDS in contact with water, forming a structure like a gel, probably occurred, inducing the closing of the pores and thereby limiting the water intrusion into the tablets

From compressibility to structural investigation of sodium dodecyl sulphate — Part 2: A singular behavior under pressure

Investigations were carried out to elucidate the compression behavior of a powdered surfactant, sodium dodecyl sulphate (SDS), based on a comparison with the main component of a detergent formulation, i.e. the chorine provider (DCCNa). The energetic analysis based on the compression cycles highlighted a lower compressibility of SDS compared with DCCNa, especially due to its worse packing ability, larger elasticity and bad cohesion ability. Also, it pointed out that the pycnometric density seemed to be overrun under pressure whereas a residual porosity had been evidenced in the expanded tablets. DSC/DTA analysis, Raman spectroscopy as well as powder X-ray diffraction refuted the hypothesis of a physico-chemical transformation of SDS under pressure. This was in accordance with the morphology of the SDS particles, quite unchanged after compression. The pycnometric density measurements have been improved; firstly, it allowed to properly express the compaction ratio of the ejected SDS tablets, and secondly, it led to conclude to a reversible intrinsic compressibility for pressures higher than 50 MPa, explained by the predominant elastic behavior of SDS

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Selective and efficient platinum(0)-carbene complexes as hydrosilylation catalysts.

The hydrosilylation reaction enables the production of silicon polymers. Platinum-carbene complexes are reported that catalyze the hydrosilylation reaction of alkenes with remarkable efficiency and exquisite selectivity and avoid the formation of platinum colloids. By-products, typically encountered with previous catalytic systems, are suppressed with these platinum derivatives

Characterization of porous textures in order to explain the influence of a surfactant on the end-use properties of detergent tablets

The functional characteristics (mechanical strength, disintegration and dissolution times) of effervescent detergent tablets containing chlorine provider were investigated according to the presence of a surfactant, sodium dodecyl sulphate (SDS). Tablets were compared for similar total porosity. The end-use property study highlighted that the presence of 2% of sodium dodecyl sulphate was not favorable to the tablet mechanical characteristics, inducing a lower ''bonding ability''. The linear relationship between the disintegration and dissolution times showed that the disintegration time was relevant to express the behavior of the tablets in water. The disintegration data showed two zones: when porosity was higher than 20%, the disintegration time was always lower than 2 min g-1 and similar for both formulas; for lower porosities, the disintegration time increased and was higher in the presence of the surfactant. In this second case, the released CO2 due to the reaction between adipic acid and sodium bicarbonate in water was slowed down in the presence of the surfactant, confirming the disintegration data. However, this negative effect of SDS on the disintegration time could not be linked to a difference of pore size distribution between the two formulas. So, despite the creation of weak interparticle bonds with the other compounds of the formula, the presence of SDS increased the disintegration by limiting the water uptake, independently of the porous texture. Moreover, no preferential localization of the surfactant at the surface of the tablet might be involved to explain the effect of SDS on the tablet accessibility by water

Dissolution of a surfactant-containing active porous material

We have studied the imbibition and dissolution of a porous material in two separate scenarios: (1) when the porous material contains a surfactant powder and (2) when the porous material is dissolved in a surfactant solution. We show that the dissolution kinetics in both scenarios is significantly affected by the presence of the surfactant and results in an increase in the characteristic imbibition time of the porous material, which can be well understood in the framework of the classical law of capillarity. Slowing of the imbibition kinetics was found to be affected by a modification of the liquid wetting properties, but is also affected by a variation in the solubility of the porous material in the presence of the surfactant. Furthermore, there is a depletion effect of the surfactant inside the rising liquid, which is in good agreement with previous work and theoretical predictions

Second Generation N-Heterocyclic Carbene—Pt(0) Complexes as Efficient Catalysts for the Hydrosilylation of Alkenes.

A new class of benzimidazolylidene carbene-Pt(0) complexes was developed and used to efficiently catalyse the hydrosilylation of alkenes

Second generation N-heterocyclic carbene-Pt(0) complexes as efficient catalysts for the hydrosilylation of alkenes

A new class of benzimidazolylidene carbene-Pt(0) complexes was developed and used to efficiently catalyse the hydrosilylation of alkenes