mJ/m²
millijoule per square meter
Surface tensionexact by definition
The millijoule per square metre is exactly 10⁻³ N/m, and identically one millinewton per metre. It is the unit of surface free energy in adhesion, coating and wetting work: water is 72 mJ/m², polyethylene about 31, and untreated PTFE around 18, which is why nothing sticks to it.
| 1 mJ/m² | 1 mN/m |