Intermolecular interactions are the types of attractive and repelling forces that occur between atoms of different molecules.  Dry ice is the solid form of carbon dioxide (CO2).  Carbon dioxide is a linear molecule composed of a carbon atom at the center and two oxygen atoms at the ends.  The carbon is double bonded to both oxygen atoms.  As a result, carbon dioxide has no net dipole moment, meaning it is a non polar compound.  It cannot form any charged interactions or hydrogen bonds with itself, so the only intermolecular forces it can exert are Van der Waals forces.  Van der Waals forces are sort of a general term for weak intermolecular forces between molecules.  At any given moment in time, there can be attractive or repulsive forces between neighboring atoms of different molecules that have partial charges due to instantaneous dipole moments.  But these interactions are generally very weak.