Technical advantage offered by the CPS Disc Centrifuge at the University of Sheffield
Technical advantage offered by the CPS Disc Centrifuge at the University of Sheffield
Biggleswade, UK, 11th March 2009: University of Sheffield has used CPS Disc Centrifuge photosedimentometry to size a wide range of latexes, sols and colloidal nanocomposite particles over the last fifteen years.
Professor Steve Armes, Department of Chemistry, University of Sheffield, says: “Our high resolution 24,000 rpm CPS Disc Centrifuge was installed and commissioned in Jan 2009. We have obtained reliable results with a wide range of latexes and nanocomposite particles. This new instrument has a maximum centrifugation rate of 24,000 rpm, which is substantially faster than our old Brookhaven disc centrifuge (15,000 rpm). This means that much smaller particles can now be sized with good accuracy and reproducibility.
Our CPS Disc Centrifuge has proved to be particularly useful for sizing our new poly (2-hydropropyl methacrylate) latexes prepared by aqueous dispersion polymerisation (see A. M. Ali et al., Soft Matter, 2007, 2, 1003-1013). Since poly (2-hydroxypropyl methacrylate) is soluble in alcohol, these particular latexes become swollen in methanol/water mixtures, which is the normal spin fluid used for our Brookhaven instrument. This means that the solid-state particle density determined by helium pycnometry is no longer applicable, which invalidates the particle size measurement. In contrast, the wholly aqueous spin fluid used in the CPS Disc Centrifuge prevents latex swelling and allows meaningful particle size analyses to be undertaken (see below). A scanning electron micrograph image of the same poly (2-hydroxypropyl methacrylate) latex is included as a comparison.
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