Volume-15 (12/2006)

Nanoparticle Surface Energy Determinations
(Smaller Particles – Smaller Problems)

A nanoparticle is a particle with at least one dimension in the range of 100 nm or less. Nanoparticles can be formed from any of a vast variety of materials, typically by rapidly diminishing the solubility of the material and condensing it into exceeding small individual particles. Much research goes into specific nanoparticle formation methods, often employing such rapid condensation techniques as super critical fluid (SCF) expansion, micro-mixing, and the like. In medicine, the uses are seemingly without end - from wound patch applications, to growth inhibitors for tumours, to enhanced drug delivery for inhalables and transdermals. In these, and most nanoparticle applications, the enhanced surface area of nanoparticles based on their smaller size is the key. With that comes the need for understanding what the exact nature of that surface is, in terms of its abilities to interact with (adhere to) other surfaces, as well as to be dispersed in the case of colloidal applications. In other words, the component surface energies of their surfaces need to be identified and understood.

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How effective is hot-wax treatment?

The hot-wax program of mechanical automobile washers is intended to ensure effective and clean drying by hydrophobization. In order to be able to measure this effect contact angle measurements were made on the bodies of two automobiles using the MobileDrop mobile instrument, which is also suitable for the non-destructive testing of large samples. With the new automobile used for the test it was possible to demonstrate a small positive effect of the treatment on the surface free energy and its polar fraction. On a damaged surface an unwanted better wettability by water was observed; this could not be reduced by the hot-wax treatment.

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