Van de Waals (VdW) forces are intermolecular forces that are for example, due to spontaneous polarisation effects between atoms. As far as I understand, they occur between any type of atom/molecule/material, it does not matter if it’s an insulating or conducting material, if there are filled electronic shells etc.
One often hears about these VdW forces in the context of molecules or small particles. Sometimes it is also mentioned for macroscopic objects e.g. Geckos which climb a wall.
However, also the Casimir effect is due to relativistic, retarded VdW forces. There one has two macroscopic metal plates separated by a distance. The plates will then slowly attract and get closer.
My question is:
Is there a similar effect as the Casimir effect but with non-metallic materials? Do macroscopic objects which are separated by a macroscopic distance attract each other by VdW forces (although the effect may be small)? For example: if we have two non-metallic plates floating in free space, would they eventually attract each other due to VdW forces?