Thin films with chemically graded functionality based on fluorine polymers and stainless steel

Area of Science:

• Materials Science
• Biomaterials Engineering
• Surface Chemistry

Background:

• Stainless steel 316L (SS316L) is a common biomaterial for stents.
• Current SS316L surfaces may require modification for improved biocompatibility and performance.
• Functionally graded materials offer tailored surface properties.

Purpose of the Study:

• To develop a functionally graded coating for SS316L biomaterials.
• To enhance non-ferromagnetic characteristics and wettability of stent surfaces.
• To ensure excellent adhesion between the coating and the SS316L substrate.

Main Methods:

• Co-deposition of stainless steel and poly(tetrafluoroethylene) thin films via radiofrequency magnetron sputtering.
• Controlled variation of fluorine content during deposition.
• Characterization of chemical and phase composition of the thin films.

Main Results:

• Thin films evolved from ferritic (alpha) to amorphous phases with FeF(2) as fluorine content increased.
• An austenitic (111) phase (gamma) was observed at intermediate fluorine concentrations.
• Optimal fluorine content for desired properties was found to be between 10 and 20 at.%.
• Coatings exhibited an average thickness of 500 nm.

Conclusions:

• Functionally graded coatings of stainless steel and poly(tetrafluoroethylene) can be successfully produced.
• Fluorine content critically influences the phase evolution and properties of the thin films.
• Coatings with 10-20 at.% fluorine show promise for modifying SS316L surfaces in biomedical applications.