Features of LPCAT Processing

The mode of creation of polymerizable or chemically reactive species, i.e., chemically reactive species, is the interaction with excited neutrals of the carrier gas (no bombardment of electrons and ions). 

The kinetic pathlength is short due to the high one-directional transport velocity of polymerizable species. 

Whether any of these characteristic features is an advantage or a disadvantage entirely depends on the objectives to be accomplished by the process. However, these two characteristic features indicate that LPCAT process is better suited for the surface treatment by excited neutrals of Ar than the surface coating. 

The first feature that chemically reactive species are created by the interaction of molecules (in gas phase or on the surface) with excited neutral species of Ar has a very significant influence in the surface modification of polymers. When a polymer surface is exposed to Ar or O2 plasma, the energetic ions and electrons (at the level of ionization energy) bombard the surface. The influence on the surface is determined by the energy level. The chemical bonds involved in the molecules that constitute the surface are relatively low (3 eV) compared to the ionization energy of the gas used in plasma (over lOeV). 

The ideal surface modification of powders is the process that breaks down the aggregates and modifies the surface of the primary particles simultaneously. LPCAT treatment could be very close to this ideal situation. The supersonic velocity of reactive species breaks up the existing aggregates to a significant level, if not completely, allowing the chemically reactive species to interact with the primary particle surface. 

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