The reactivity ratios r1 (EO) and r2 (PO) for the copolymerization of ethylene oxide (EO) and propylene oxide (PO) have been determined. The reactions were carried out in dry dimethyl formamide at 90°C using the potassium salt of ethylene glycol as initiator. The polymer composition at different EO/PO ratios in the feed was determined by 1H-NMR. Using the Fineman-Ross method to calculate reactivity ratios from the values of polymer composition, rl- and r2-values of 1.8 and 0.3, respectively, were obtained.
In this paper the phase behaviour and physical properties of a series of alkyl (C6, C8, C12 and iso-C8) monoglycerol ethers and 2-hydroxyalkyl (C6, C8, C12) monoglycerol ethers are presented. The binary phase diagram for the surfactants shows very little dependence on temperature. It is shown that as the alkyl chain length increases the tendency to form lamellar liquid crystalline phases increases. The branched alkyl chain shows no formation of lamellar phase even at high concentrations of surfactant. The differences in phase behaviour between the surfactants is attributed to the variation in the critical packing parameter (CPP) of the surfactants. The presence of an additional hydroxyl group in the alkyl chain causes a temperature independent solubility behaviour. Ternary phase diagrams were prepared using dodecane as the oil phase. Hexyl glycerol ether was the only of the alkyl glycerol ethers which was sufficiently water soluble to determine the surface tension and CMC. The CMC was determined to 15 mM (and surface tension to 26 mN m-1).
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.
A new method to determine glass corrosion/etching is presented. The method enables a rapid screening of formulations in terms of their glass etching tendency as well as identification of the main components responsible for giving rise to the etching. Up to four formulations can be evaluated during one day. The high sensitivity of the QCM-D instrument enables measuring the etching of thicknesses less than one nm. Therefore, the technique can be used efficiently to screen components in the formulations and aid in the development phase of new tformatoptimised dishwash detergent formulations. In a planned work we will investigate the correlation between the etching rate of thin sputtered glass films at the surface of QCM-D crystals and good performance in a standardized dishwasher test using meltquenched glasses.
The foam stability of aqueous solutions of pentaethylene glycol n-decyl ether and pentaethylene glycol n-dodecyl ether surfactants was related to experimental studies carried out on thin horizontal microscopic single films of the surfactant solutions using the microinterferometric film apparatus developed by Scheludko [1]. It was observed that an initial decrease in film thickness and reduction in potential at the air/solution interface of the film, occurred at a critical surfactant concentration where "black spots" appeared in the film when it was observed in reflected light. The black spots appeared to expand and coalesce, until the entire sheet was thinned down to a metastable common black film. In addition, a sharp increase in foam stability occured above this surfactant concentration, which was about 0.1 c. m. c, and corresponded to a high surface adsorption density of surfactant. We believe that the cause of the phenomenon was a change in state of the surfactant monolayer as originally proposed by Scheludko and Exerowa [2, 3]. Such a change (condensation) from gaseous to liquid expanded monolayers, has already been established for ionic surfactants and may change the rheological properties of the adsorbed film, enhancing the foam stability. Finally, the foam stability was determined at a range of electrolyte (KCI) concentrations from which it could be suggested that two types offoam stabilization methods were operating In the low electrolyte concentration, the stability appeared to be controlled by the metastable common first black film, but at high electrolyte concentrations the stability seemed to be dependent on secondary "Newton black" films