Concentration-Dominated Orientation of Phenyl Groups at the Polystyrene/Graphene Interface

Area of Science:

• Materials Science
• Polymer Science
• Surface Chemistry

Background:

• The properties of graphene-based aromatic polymer nanocomposites are significantly influenced by the interfacial orientation of aromatic groups.
• Understanding this orientation is key to designing advanced materials.

Purpose of the Study:

• To investigate the interfacial orientation of polystyrene (PS) phenyl groups in contact with graphene.
• To elucidate the relationship between interfacial concentration and phenyl group orientation.

Main Methods:

• Sum frequency generation (SFG) vibrational spectroscopy was employed to probe the interfacial orientation.
• Analysis of SFG spectra provided insights into the molecular arrangement at the graphene-polymer interface.

Main Results:

• Phenyl group orientation is concentration-dependent, reaching a quasi-equilibrium state.
• At low concentrations, phenyl groups recline for face-to-face interaction with graphene.
• At high concentrations, phenyl groups orient upright, forming inter-chain pi-pi interactions and edge-to-face interactions with graphene.

Conclusions:

• The study reveals distinct interfacial orientations of PS phenyl groups on graphene based on concentration.
• These findings are crucial for optimizing the design and performance of graphene-based aromatic polymer nanocomposites through controlled pi-pi interactions.