What is interfacial tension ?

       The interfacial tension can be regarded as the contraction force acting on the liquid interface per unit length, which is equal in value to the interface energy. The force of the liquid in contact with another immiscible liquid is called the interfacial tension between the liquid phase and the liquid phase. The liquid is in contact with the solid surface, and the force generated at the interface is called the interfacial tension between the liquid phase and the solid phase. The interfacial tension between the interface of the solid surface and the air is the free energy of the solid surface. The materials with different solid surfaces have different surface free energies. The energy of metals and general inorganic surfaces is above 100mN/m, which is called high-energy surface. The surface of organic materials such as plastics has low energy and is called low-energy surface.