The investigation of polymer surface dynamics modified by plasma using dynamic contact angle method

According to the changes of surface dynamic decay rate constant and dynamic contact angle hysteresis in the entire range of CF4(%) in CF4/CH4 plasma feed gas, the whole range can be divided into three regions, which are distinguished by their different plasma reaction mechanistic and properties of the polymerized films. The rate constant of first water immersion stage for polymer films pretreated by CH4 plasma, and then treated by CF4/CH4 plasma is smaller than that of unpretreated films. This demonstrated that an ultrathin layer of plasma polymer of methane as a barrier layer, placed prior to CF4/CH4 plasma treatment, can significantly reduced the decay. Arrhenius plots of the decay rate constants on the water immersion temperature showed conspicuous breaks at characteristic surface transition temperature Ts, which represents the change of driving force due to the change in basic properties of water in contact with a surface at the Drost-Hansen temperature of 15°C. The activation energy for the surface configuration change at above and below Ts is relatively small. The basic nature of the surface configuration change is relatively simple rotational motion without involving large segments or migration of whole macromolecules.