Self-propelled Janus colloids (JCs) have recently gained
much attention
due to their ability to move autonomously and mimic biological microswimmers.
This ability makes them suitable for prospective drug/cargo-delivery
applications in microscopic domains. Understanding their dynamics
in surroundings doped with macromolecules such as polymers is crucial,
as most of the target application media are complex in nature. In
this study, we investigate the self-diffusiophoretic motion of hydrogen
peroxide-fuelled SiO2–Pt JCs in the presence of
dilute amounts of poly(ethylene oxide) (PEO). Despite the addition
of PEO chains producing a Newtonian behavior with negligible increase
in viscosity, the ballistic movement and rotational fluctuations of
active JCs are observed to be significantly suppressed. With an increase
in the polymer concentration, this leads to a transition from smooth
to jittery to cage-hopping to the arrested motion of active JCs. We
further propose that the anisotropic interaction of the polymers with
the JC increases the “local drag” of the medium, resulting
in the unusual impediment of the active motion.