A simple and reliable didactic laboratory has been developed to illustrate fundamental concepts of hydrophilicity, hydrophobicity, wetting, and spreading phenomena for undergraduate students. The described laboratory includes preparation of surfactant solutions at different concentrations and applying droplets of these solutions on a hydrophobic surface followed by imaging the applied droplets using a cost-effective USB digital microscope connected to a computer. Contact-angle values of droplets were measured using ImageJ, a freely available image-processing software. Students constructed surfactant-concentration−contact-angle plots to determine the surfactant's critical-micelle-concentration value. The feasibility of the described didactic laboratory and the achievement of the intended learning outcomes (ILOs) were evaluated through complementary assessment tools, including lab reports, homework assignments, and students' feedback. The described laboratory was found to be cost-effective, safe, reproducible, and successful in achieving the ILOs.

A simple, reliable, and cost-effective experiment is presented in which students synthesized citrate-capped gold nanoparticles (GNPs), functionalized them with poly(ethylene glycol) (PEG), and transferred the PEG-GNPs from water to the organic phase dichloromethane. The experiment introduces students to nanotechnology with foci on important concepts including surface modification of nanoparticles, colloidal stability, and phase transfer. The proposed experiment was evaluated at three different universities to confirm its reproducibility and versatility. Collectively, the proposed experiment is suitable to be implemented into colloid-or nanoscience-related curricula.