Estimation of polymer-surface interfacial interaction strength by a contact AFM technique

Area of Science:

• Materials Science
• Surface Science
• Polymer Science

Background:

• Understanding polymer-surface interactions is crucial for material adhesion and performance.
• Characterizing interfacial forces informs material design and application.
• Existing methods may not precisely quantify the absolute interaction strength of polymer monolayers.

Purpose of the Study:

• To quantitatively measure the interfacial interaction strength between polymer monolayers and solid surfaces.
• To investigate the influence of polymer properties and surface treatments on interaction forces.
• To establish a reliable method for determining polymer adhesion forces.

Main Methods:

• Utilized contact-mode atomic force microscopy (AFM) to scratch polymer monolayers from treated glass surfaces.
• Employed tapping-mode AFM to measure the depth of the created recess.
• Verified scratch depth using optical phase interference microscopy (OPIM).

Main Results:

• Determined the force required for complete polymer layer removal without substrate damage.
• Quantified interaction strengths for polypropylene (PP), low-density polyethylene (PE), and PP-grafted-maleic anhydride (PP-g-ma).
• Found interaction forces to be predominantly van der Waals (VDW) in nature.

Conclusions:

• Interfacial interaction strength is governed by VDW forces, wetting behavior (hydrophobic/hydrophilic), and hydrogen bonding.
• AFM provides a robust method for quantifying polymer-surface adhesion.
• Surface treatment and polymer chemistry significantly impact interfacial strength.