Colloidal particles partially coated with platinum and dispersed in H2O2 solution are often used as model self-propelled colloids. Most current data suggest that neutral self-diffusiophoresis propels these particles. However, several studies have shown strong ionic effects in this and related systems, such as a reduction of propulsion speed by salt. We investigate these ionic effects in Pt-coated polystyrene colloids, and find here that the direction of propulsion can be reversed by addition of an ionic surfactant, and that although adding pH neutral salts reduces the propulsion speed, adding the strong base NaOH has little effect. We use these data, as well as measured reaction rates, to argue against propulsion by either neutral or ionic self-diffusiophoresis, and suggest instead that the particle's propulsion mechanism may in fact bear close resemblance to that operative in bimetallic swimmers.
Ionic effects in self-propelled Pt-coated Janus swimmers.
Published 2013 in Soft Matter
ABSTRACT
PUBLICATION RECORD
- Publication year
2013
- Venue
Soft Matter
- Publication date
2013-12-15
- Fields of study
Physics, Medicine, Materials Science, Chemistry
- Identifiers
- External record
- Source metadata
Semantic Scholar, PubMed
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