What material presents in greater magnitude the property of shrinkage when warm -say 25 Celsius and expand when cold -say 5 Celsius ?

Under pressure, water will freeze at a hotter temperature. Since ice is less dense that liquid water, this could possibly fit your description at >1 atm.

Water, silicon, and bismuth expand on freezing.

Gallium is another good example.

Does anyone know about rubber behavior ?

Edited September 24, 200817 yr by Externet
Error

Rubber is another material that tends to contract upon heating. Long molecules, stretched when cold, but bent when heated.