Improved adhesion between PMMA and stainless steel modified with PMMA brushes

Area of Science:

• Materials Science
• Polymer Chemistry
• Surface Engineering

Background:

• Adhesion between polymers and metal surfaces is crucial for many applications.
• Polymer brushes can enhance interfacial properties.
• Stainless steel (SS) is a common material requiring improved polymer adhesion.

Purpose of the Study:

• To synthesize poly(methyl methacrylate) (PMMA) brushes on SS surfaces.
• To evaluate the adhesion strength of PMMA bulk to PMMA-brushed SS joints.
• To identify optimal conditions for injection molding to maximize adhesion.

Main Methods:

• Surface-initiated atom transfer radical polymerization (ATRP) to create PMMA brushes on SS.
• Injection molding to create joints between bulk PMMA and brushed SS.
• Tensile testing to assess the degree of adhesion.

Main Results:

• Specific injection molding conditions (preheating SS, long packing time, mold temperature above Tg) reduce residual stress and improve mixing.
• Cohesive failure within the bulk PMMA indicates strong interfacial adhesion.
• High density and long PMMA brush lengths significantly enhance adhesion strength.
• Stress concentration at the rim due to cooling can lead to weak adhesion at the joint's edge.

Conclusions:

• Optimized injection molding parameters are essential for achieving strong PMMA-SS joints.
• PMMA brush characteristics, specifically high density and length, are key factors for robust adhesion.
• Surface modification with PMMA brushes offers a viable strategy for improving polymer-metal adhesion.