Surface adsorption of polar end-functionalised polystyrenes

Area of Science:

• Polymer Science
• Materials Science
• Surface Chemistry

Background:

• Polar end-functionalised polymers typically exhibit low adsorption to external blend surfaces due to high surface energy.
• Adsorption can be induced by annealing in a polar environment, followed by quenching to a glassy state.

Purpose of the Study:

• To investigate the adsorption behavior of carboxy end-functionalised deuteriopolystyrene (dPS-COOH) in blends with hydrogenous polystyrene (hPS).
• To determine the effect of multiple functional groups on the surface activity of polymers.

Main Methods:

• Annealing blended films of dPS-COOH and hPS in glycerol at 150 °C.
• Quenching the films to below the glass transition temperature.
• Quantifying surface excess using Nuclear Reaction Analysis (NRA).
• Utilizing Self-Consistent Mean Field Theory (SCMFT) to calculate thermodynamic sticking energies.

Main Results:

• Annealing in glycerol successfully induced adsorption of dPS-COOH to the blend surface.
• Chains with multiple carboxy groups (dPS-2COOH) exhibited significantly higher surface activity compared to singly functionalised chains (dPS-COOH).
• Carboxy groups showed a much higher thermodynamic sticking energy (1.3-1.7) at the polystyrene-glycerol interface than ester groups (0.3).

Conclusions:

• Multiple functional groups, particularly carboxy groups, dramatically enhance polymer adsorption to surfaces when annealed in a polar environment.
• The findings provide insights into controlling polymer surface properties through functionalisation and annealing strategies.
• SCMFT calculations support the experimental observations, quantifying the superior surface affinity of carboxy functionalities.