Vertical Cylinder-to-Lamella Transition in Thin Block Copolymer Films Induced by In-Plane Electric Field

Area of Science:

• Materials Science
• Polymer Science
• Nanotechnology

Background:

• Block copolymers exhibit complex morphologies dependent on processing conditions.
• Electric fields and solvent vapor are key external stimuli for controlling polymer film structure.

Purpose of the Study:

• To investigate the morphological transitions in polystyrene-block-poly(4-vinyl pyridine) films.
• To understand the influence of electric fields and solvent vapor on self-assembly.
• To explore the effect of gold nanorod doping on film morphology.

Main Methods:

• Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used for morphological analysis.
• Simultaneous exposure to in-plane electric fields and saturated solvent vapor was employed.
• Gold nanorods were incorporated to modify dielectric properties.

Main Results:

• Standing cylinders of poly(4-vinyl pyridine) formed threads along the electric field direction.
• These threads partially merged into standing lamellar structures.
• Doping with gold nanorods enhanced ordering, while non-selective chloroform vapor facilitated the transition, unlike selective 1,4-dioxane vapor.

Conclusions:

• The study demonstrates a controllable morphological transition in block copolymer films.
• Electric fields and solvent vapor are effective tools for directing self-assembly.
• Gold nanorod doping can enhance the ordering and dielectric properties of the resulting nanostructures.