Why do cloths and foams absorb water, but metals and plastics don’t?
In: Other
This is quite a complex area and not my specialty, but, consider the structure of the materials you have specified. Cloths and foams are porous/fibrous while metals and plastics are typically bulk solid (i.e. solid all the way through). You can make ‘swiss-cheese’ like metals and plastics (such as a common dish sponge).
So, that being said:
1. Water – water molecules are attracted to one another thanks to hydrogen bonding, This attraction means molecules around one another will ‘group up’ when in close proximity and is what leads to [surface tension](https://i.imgur.com/tcfZqVr.jpg).
2. [Wetting angle](https://i.imgur.com/0eFXzY5.png) – this is the angle a liquid makes with a solid and is a property of the hydrophobicity (dislike of water) or hydrophilicity (like of water).
3. [Capillary action](https://en.wikipedia.org/wiki/Capillary_action) – the process where a liquid can flow through narrow spaces without assistance, or even going against other forces such as gravity. This is facilitated by the intermolecular forces (i.e. between the liquid and the solid).
4. The combination of surface tension (within the liquid – water) and adhesion between solid and liquid, plus the structure of the solid can allow for liquid to be drawn up.
Cloths, foams, and sponges have structure and chemistry that are amenable to this. The structures of bulk materials such as metals and plastics do not typically allow for this, **however** that doesn’t mean it isn’t possible.
Check out [this image](https://i.imgur.com/Lz5aQDv.png) ([source thesis](https://repository.lboro.ac.uk/articles/thesis/Polyvinylidene_fluoride_membranes_with_engineered_porosity_role_of_temperature_and_substrate_morphology_in_phase_inversion_processes/10288532)) showing a dual microstructure with a porous phase on one edge
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