Synchronization modes of chitosan surfers with various sizes

Transition from partial to complete synchrony is generally governed in coupled oscillator networks by systematic tuning of the coupling strength. In active matter systems, however, such controlled progression is far more elusive, owing to the intrinsically weaker interactions and erratic motility of particles. Here, we investigate the collective dynamics of three and four chitosan motors at the air-liquid interface, where the effective coupling emerges from the competition between capillary attraction and Marangoni-driven repulsion. By tuning the bead size, we modulate the coupling strength and thereby the synchronization modes. For quasi-identical beads, chitosan beads exhibit collective synchrony with breathing-like behavior, whereas size asymmetry gives rise to partial synchrony. In the four-bead configuration, sensitivity to initial conditions leads to markedly different macroscopic trajectories, including switching between synchronization states. The temporal evolution of inter-beads distance and synchronization phases quantitatively confirms these transitions.