Development and Evaluation of Polyether Ether Ketone (PEEK) Capillary for Electrospray

With the rapid development of nanotechnology, there is urgent need of characterizing techniques; especially determining the particle size distribution directly from solution. Dynamic light scattering is often used but presence of a small number of aggregates can greatly influence the size distribution. Electrospray scanning mobility particle sizer (ES-SMPS) is rapidly emerging as an alternative method in colloidal science. However, a major limitation is the use of silica-coated capillaries, which are negatively charged at pH > 3, and therefore making its use difficult for positively charged nanoparticles. In this work, we have developed the polyether ether ketone (PEEK) capillary for ES-SMPS, which removes this limitation because it carries no charge. We have shown that the new capillary not only produced equally good particle size distributions for negatively charged particles (SiO₂, Au, and latex) as obtained with silica capillaries, but also precise particle size distributions for positively charged particles (TiO₂). Moreover, the PEEK capillaries are much cheaper than the silica capillaries. Thus, the results shown in this paper strengthen the development of the ES-SMPS method as a versatile method for determining the particle size distributions of colloidal sols directly from solution.