Solvent vapor mediated polymer adsorption in thin films.

Area of Science:

• Polymer Science
• Materials Science
• Surface Chemistry

Background:

• Thin polymer films are crucial in various applications.
• Understanding polymer chain diffusion and reorganization is key to controlling film properties.
• Annealing processes, both thermal and solvent-based, are used to modify polymer films.

Purpose of the Study:

• To compare the effectiveness of solvent annealing versus thermal annealing on polystyrene films.
• To investigate the surface excess of specific polymers (hPSF and hPS-PDMS) in deuterated polystyrene (dPS) films after annealing.
• To elucidate the mechanisms behind polymer adsorption and diffusion during annealing.

Main Methods:

• Solvent annealing using controlled cyclohexane vapor absorption.
• Thermal annealing under vacuum above the glass transition temperature.
• Elastic Recoil Detection Analysis (ERDA) to quantify surface excess of polymers.

Main Results:

• Both annealing methods facilitated polymer diffusion.
• Thermal annealing, but not solvent annealing, resulted in surface excess for hPSF/dPS films due to cyclohexane's low surface tension.
• hPS-PDMS formed surface excess layers in solvent-annealed films, indicating saturated monolayer formation.
• Unfavorable interactions and micelle formation inhibited hPS-PDMS mixing and surface layer formation in dPS.

Conclusions:

• Solvent annealing effectiveness is polymer-specific and influenced by solvent surface tension.
• Thermal annealing is more effective for achieving surface excess of certain polymers like hPSF.
• Polymer architecture (e.g., block copolymers) and intermolecular interactions significantly impact annealing outcomes and surface morphology.