In complex colloidal systems, particle-poor regions can develop within particle-rich phases during sedimentation or creaming. These particle-poor regions are overlooked by 1D profiles, which are typically used to assess particle distributions in a sample. Alternative methods to visualise and quantify these regions are required to better understand phase separation, which is the focus of this paper. Magnetic resonance imaging has been used to monitor the development of compositional heterogeneity in a vesicle-polymer mixture undergoing creaming. T relaxation time maps were used to identify the distribution of vesicles, with vesicle-poor regions exhibiting higher T relaxation times than regions richer in vesicles. Phase separated structures displayed a range of different morphologies and a variety of image analysis methods, including first-order statistics, Fourier transformation, grey level co-occurrence matrices and Moran's I spatial autocorrelation, were used to characterise these structures, and quantify their heterogeneity. Of the image analysis techniques used, Moran's I was found to be the most effective at quantifying the degree and morphology of phase separation, providing a robust, quantitative measure by which comparisons can be made between a diverse range of systems undergoing phase separation. The sensitivity of Moran's I can be enhanced by the choice of weight matrices used.

The interactions between supported cationic surfactant bilayers were measured by colloidal probe atomic force spectroscopy and the eect of dierent halide salts was investigated. Di(alkyl iso-propyl ester) dimethyl ammonium methylsulfate (DIPED-MAMS) bilayers were fabricated by the vesicle fusion technique on muscovite mica.The interactions between the bilayers were measured in increasing concentrations of 1 NaCl, NaBr, NaI and CaCl 2 . In NaCl the bilayer interactions were repulsive at all concentrations investigated, and the Debye length and surface potential were observed to decrease with increasing concentration. The interactions were found to follow the Electrical Double Layer (EDL) component of DLVO theory well. However Van der Waals forces were not detected, instead a strong hydration repulsion was observed at short separations. CaCl 2 had a similar eect on the interactions as NaCl. NaBr and NaI were observed to be more ecient at decreasing the surface potential than the chloride salts, with the ecacy increasing with the ionic radius.

To enable the simultaneous determination of both the speed and extent of liquid absorption in cotton fabrics, we have developed a radial, horizontal wicking experiment. The initial part of the absorbed mass versus time profile is linear, which allows us to determine the wicking rate. After a given time, a constant mass is reached, corresponding to the liquid absorption capacity of the fabric. Using the method proposed, we show that a fabric conditioner does not affect the physical characteristics. such as porosity and pore size, and hence the water absorption capacity of cotton terry. On the other hand, there is a pronounced effect on the wicking rate. Based on the experimentally determined values of the contact angle of water on the treated fabrics, the differences in wicking rates as a function of the kind of fabric conditioner can be ascribed to differences in wettability.

No abstract

No abstract