Plasma material modification process

This article mainly introduces the process of plasma material modification. What is plasma modification?

Plasma modification refers to the use of free radicals, ions, excited substances, ultraviolet light, etc. in plasma to change the surface of the material:

Chemical composition (functional group)

Energy (hydrophilic/hydrophobic)

Roughness

4,Adhesion ability

5,Cleanliness

Plasma action depths are typically only 1–10 nm and are pure "surface engineering" that does not alter the material properties.

Plasma material modification process

Take PEEK as an example:

Step 1: Break the old key

The energetic particles (electrons, ions, etc.) in the plasma bombard the surface of PEEK like countless tiny bullets.

These particles are energetic enough to break the originally stable C-C and C-H bonds in the PEEK molecular chain.

Many carbon atoms with "broken arms" appear on the surface, which we call free radicals. These free radicals are in an extremely unstable state and are eager to grab new atoms to fill the gaps.

Step 2: Graft the new group

This is the core of modification. Once there are free radicals on the surface, the reaction occurs as long as there is an active element in the environment, usually using oxygen O2 or air as a process gas.

Chemical reaction: Oxygen radicals produced by gas ionization or oxygen in the air quickly combine with carbon atoms on the surface of the "broken arm".Introduce functional groups, and the treated surface successfully introduces oxygen-containing functional groups, mainly including:

O

C=O

COO

3. Modification result: from "water hate" to "hydrophilicity"

Increased polarity: These oxygen-containing functional groups (C-O, C=O, COO) introduced are polar groups. Surface can be improved: They are like tiny "grippers" that can hold water molecules tightly. Commonly used gas systems for plasma modification

Gas system	Main role	Apply
O₂ plasma	Strong introduction of –OH, –C=O, –COOH to increase surface energy	Bonding, coating, pre-printing treatment
Ar plasma	Broken keys, clean, slightly etched	Further connect to O₂ / N₂ to do functionalization
N₂ plasma	Nitrogen-containing functional group (–NH₂) is introduced, suitable for biomaterials	Medical PEEK, connectors
CF₄ / O₂Mix	Modify + control etching	Microstructure design
H₂ plasma	Reduce the carbonization layer	Commonly used in the medical industry

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