Self Assembly of Block CopolymersSelf Assembly of Block Copolymers

Name:

Donal O’Donoghue, National University of Ireland, Cork.

Research Group:

Prof. Glenn Fredrickson’s group in the Complex Fluid Design Consortium

Supervisor:

Dr. Nathaniel Lynd

Project Overview:

Numerically investigating the nano scale architectures of different block copolymer melts formed by microphase separation, using self consistent field theory (SCFT).

Why is this research of interest to us?Why is this research of interest to us?

• Thermoplastic elastomers (TPE), materials which can be stretched and heated up and yet return to their original shape, can be made with block copolymers.

• TPE’s are utilised in many different products, such as shoe soles, gaskets, tires, etc. Hence this research is of interest to many different industries.

• Block copolymers are of interest from a purely scientific point of view since they “microphase separate” to form periodic nanostructures of various different architectures.

Microphase Separation of Diblock Microphase Separation of Diblock CopolymersCopolymers

• Diblock copolymers will self-assemble into different structures depending on their composition.

• Parameters which are important are the interaction strength between different monomer species A and B, N, and the fractional composition of the monomer species A, fA .

Using Self Consistent Mean Field Theory To Using Self Consistent Mean Field Theory To Numerically Investigate Diblock CopolymersNumerically Investigate Diblock Copolymers

Polymers are modelled as smooth space curves, which follow Gaussian chain statistics

Polymers deform with a spring-like stretching energy (like microscopic elastic threads)

• Interaction between A/B segments treated as simple contact forces

• Our particle based theory is then changed to a field theory using a mathematical transformation.

• Contact forces are replaced by an interaction field

• Incompressibility condition replaced by a Lagrange field

• Polymer concentrations as a function of space are calculated from a set of self consistent equations.