Highly ordered hierarchical poly(ethylene oxide)-b-polystyrene/organoclay nanocomposites

Area of Science:

• Materials Science
• Polymer Science
• Nanotechnology

Background:

• Block copolymers like poly(ethylene oxide)-b-polystyrene (PEO-b-PS) can self-assemble into ordered nanostructures.
• Organoclay incorporation can modify polymer properties and create nanocomposites.
• Controlling the hierarchical structure of polymer nanocomposites is crucial for advanced applications.

Purpose of the Study:

• To fabricate a lamellar-forming PEO-b-PS/organoclay nanocomposite with a unique hierarchical structure.
• To investigate the structural organization and orientation of polymer chains and clay platelets within the nanocomposite.
• To understand the influence of organoclay on the crystalline orientation of PEO within the nanocomposite.

Main Methods:

• Fabrication of the nanocomposite via solution casting of PEO-b-PS and organoclay blends.
• Annealing the blends at 180 °C for 8 hours under uniaxial constraint to induce orientation.
• Characterization of the hierarchical structure, lamellar ordering, and crystal orientation using advanced techniques.

Main Results:

• A lamellar-forming PEO-b-PS/organoclay nanocomposite with a hierarchical structure was successfully fabricated.
• Lamellar layers were oriented parallel to the film plane, with exfoliated clay platelets localized in PEO layers and aligned parallel to the PEO/PS interface.
• Poly(ethylene oxide) crystals exhibited c-axis orientation perpendicular to phase-separated layers, with a lower orientation function compared to the neat block copolymer.

Conclusions:

• The fabrication method yields a well-defined hierarchical structure in the PEO-b-PS/organoclay nanocomposite.
• Uniaxial constraint effectively orients both the lamellar structure and the incorporated organoclay platelets.
• The presence of organoclay influences the crystalline orientation of the PEO component, leading to reduced crystal perfection.