Carbon dioxide is not polar; it is non-polar. The carbon dioxide molecule has a symmetrical structure, resulting from two identical oxygen atoms attached to a center carbon atom.
The two oxygen atoms in the carbon dioxide molecule are more electronegative than the central carbon atom. This causes the two polar bonds from carbon to oxygen to each have dipole moments going in opposite directions. As a result, the polar bonds cancel each other out leaving a net dipole moment of zero. The cancelling effect makes the molecule non-polar.
Polar and non-polar molecules are attracted to other molecules of the same kind.