Establishment of a derivatization method to quantify thiol function in sulfur-containing plasma polymer films

Area of Science:

• Materials Science
• Surface Chemistry
• Polymer Chemistry

Background:

• Thiol-supported surfaces are increasingly important in biotechnology and catalysis.
• Plasma polymerization is a promising method for creating these surfaces.
• Accurate characterization of thiol (-SH) groups is essential for controlling surface properties.

Purpose of the Study:

• To develop and validate an original chemical derivatization method for quantitatively probing -SH functions in plasma polymers.
• To investigate the reaction kinetics for accurate -SH content determination.
• To establish a reliable method for optimizing thiol density in plasma polymer films.

Main Methods:

• Utilized N-ethylmaleimide as a labeling molecule for quantitative probing of -SH groups.
• Validated the method on self-assembled monolayers of 3-mercaptopropyltrimethoxysilane as a model surface.
• Investigated the reaction kinetics, identifying a two-step mechanism (fast surface reaction followed by diffusion-limited reaction).

Main Results:

• Successfully established a quantitative chemical derivatization method for -SH groups in plasma polymers.
• The method was validated both qualitatively and quantitatively.
• Deduced a -SH group density of approximately 4% in propanethiol plasma polymers, consistent with other plasma polymer families.

Conclusions:

• The developed derivatization method provides a reliable way to quantify -SH groups in plasma polymers.
• The understanding of the reaction kinetics aids in optimizing thiol content.
• This work opens avenues for enhancing thiol-based plasma polymer films for various applications.