Revealing Interfacial Interactions in Random Copolymer Adsorbed Layers by Solvent Leaching

Area of Science:

• Polymer Science
• Materials Science
• Surface Chemistry

Background:

• Melt-state annealing of polymer films creates irreversibly adsorbed layers.
• These layers influence crucial thin film properties like diffusion and glass transition temperature.
• Adsorbed layer formation is driven by numerous monomer-substrate interactions.

Purpose of the Study:

• To investigate the adsorption behavior of polystyrene (PS), poly(methyl methacrylate) (PMMA), and their random copolymers.
• To understand how solvent selection impacts the adsorbed layer thickness and desorption.
• To probe polymer-substrate interactions using adsorbed layer thickness as a metric.

Main Methods:

• Isolation of adsorbed layers using selective solvents.
• Washing polymer films with different solvents (tetrahydrofuran, chloroform, toluene).
• Analysis of adsorbed layer thickness and desorption trends.

Main Results:

• Polystyrene (PS) adsorbed layer thickness is insensitive to solvent choice.
• Poly(methyl methacrylate) (PMMA) adsorbed layers desorb in tetrahydrofuran and chloroform but not toluene.
• Composition-dependent desorption suggests non-preferential adsorption of styrene and methyl methacrylate units.

Conclusions:

• Adsorbed layer thickness can probe specific polymer-substrate interactions.
• Copolymer adsorption during annealing is better understood, revealing non-preferential monomer interactions.
• This work enhances predictions of processing-induced property changes in heterogeneous polymer thin films.