2024 AIChE Annual Meeting
(177s) Manipulating the Motion of Active Particles of Varying Janus Balance and Aspect Ratio
Author
Young, C. M. - Presenter, University of Michigan
Brownian particles undergo random motion due to stochastic collisions with surrounding
solvent molecules. Active colloidal particles, on the other hand, undergo locomotion by
converting external energy into directed motion. Light, electric fields, magnetic fields, and
chemical reactions can provide this external energy. The conversion of energy into motion can be
achieved by creating colloids with two distinct faces (Janus), one of which asymmetrically
engages in the energy conversion. Previous research indicates that integrating active particles
into colloidal crystals composed of Brownian particles can influence the local defect structure or
facilitate the annealing of the crystal into a more ordered phase. This is attributed to the active
motion of the particles and their interaction with Brownian particles. In this study, we seek to
regulate the mobility of active particles, by pursuing the synthesis of particles of Janus balance
and aspect ratio. Spherical and ellipsoidal polystyrene particles are embedded into poly(vinyl
alcohol) (PVA) films of varying thickness, followed by the selective deposition of platinum on
the particle by means of physical vapor deposition. The portion of particles covered by platinum
coating depends on the thickness of the PVA film. By adding hydrogen peroxide, the mobility of
these active particles is enhanced because of the catalytical decomposition of hydrogen peroxide
on the platinum-coated surfaces of the particle. We hypothesize that the mobility enhancement is
contingent on the Janus balance and aspect ratio of the synthesized particles. In addition, we
study by computational simulation how the active motion of these particles in depends on these
properties of the particles by quantifying the mean square displacement of the active particles as
a function of the inputed active energy. This study provides a simple and innovative method to
synthesize and control the motion of active particles, thereby contributing to our understanding
of their behavior in colloidal crystals.
solvent molecules. Active colloidal particles, on the other hand, undergo locomotion by
converting external energy into directed motion. Light, electric fields, magnetic fields, and
chemical reactions can provide this external energy. The conversion of energy into motion can be
achieved by creating colloids with two distinct faces (Janus), one of which asymmetrically
engages in the energy conversion. Previous research indicates that integrating active particles
into colloidal crystals composed of Brownian particles can influence the local defect structure or
facilitate the annealing of the crystal into a more ordered phase. This is attributed to the active
motion of the particles and their interaction with Brownian particles. In this study, we seek to
regulate the mobility of active particles, by pursuing the synthesis of particles of Janus balance
and aspect ratio. Spherical and ellipsoidal polystyrene particles are embedded into poly(vinyl
alcohol) (PVA) films of varying thickness, followed by the selective deposition of platinum on
the particle by means of physical vapor deposition. The portion of particles covered by platinum
coating depends on the thickness of the PVA film. By adding hydrogen peroxide, the mobility of
these active particles is enhanced because of the catalytical decomposition of hydrogen peroxide
on the platinum-coated surfaces of the particle. We hypothesize that the mobility enhancement is
contingent on the Janus balance and aspect ratio of the synthesized particles. In addition, we
study by computational simulation how the active motion of these particles in depends on these
properties of the particles by quantifying the mean square displacement of the active particles as
a function of the inputed active energy. This study provides a simple and innovative method to
synthesize and control the motion of active particles, thereby contributing to our understanding
of their behavior in colloidal crystals.