Toward anisotropic materials via forced assembly coextrusion.

Area of Science:

• Materials Science
• Polymer Science
• Nanotechnology

Background:

• Multilayer coextrusion is a versatile method for studying confinement effects on self-assembling nanomaterials.
• Triblock copolymers (BCP) with cylindrical microstructures can be processed using forced assembly techniques.

Purpose of the Study:

• To investigate the influence of microdomain orientation on the mechanical behavior of multilayer BCP films.
• To understand how layer thickness affects mechanical response in different directions.

Main Methods:

• Processing of a triblock copolymer (BCP) with a cylindrical microstructure using multilayer coextrusion and forced assembly.
• Mechanical testing of multilayer films in both extrusion (ED) and transverse (TD) directions.
• Analysis of stress-strain curves to evaluate yielding behavior and extensibility.

Main Results:

• Mechanical response is influenced by cylinder orientation and interface effects, particularly with decreasing layer thickness.
• Stress applied along the cylinder axis results in sharp yielding, while perpendicular stress shows weak yielding.
• Extensibility in the ED increases with reduced layer thickness, but remains constant in the TD.

Conclusions:

• Coextrusion technology enables tunable mechanical toughness in polymers through a continuous process.
• Altering layer thickness allows for control over mechanical properties, ranging from brittle to ductile.
• This platform facilitates the design of composite materials with tailored mechanics by combining polymer properties.