  The self-assembly of submerged cold-plasma-treated polyethylene beads is
reported. The plasma-treated immersed millimetrically-sized polyethylene beads
formed well-ordered 2D quasi-crystalline structures. The submerged floating of
light polyethylene beads is possible due to the energy gain achieved by the
wetting of the high-energy plasma-treated polymer surface prevailing over the
energy loss due to the upward climb of the liquid over the beads. The capillary
immersion attraction force is responsible for the observed self-assembly. The
observed 2D quasi-crystalline structures demonstrate dislocations and point
defects. Mechanical vibration of self-assembled rafts built of polyethylene
beads leads to the healing of point defects. The immersion capillary lateral
force governs the self-assembly, whereas the elastic force is responsible for
the repulsion of polymer beads.
