UROS 2017 Project: Diblock Copolymers under a Shear-Flow Field
by Aaron Adams
As the principle investigator, I have gained valuable skills in computer code and mathematical modelling. This also acted as a test of my knowledge and abilities gained in my previous two years of study, and was good preparation for my third year. Additionally, having research experience will be important for me as I plan to go forward into teaching, and then my PhD. This project has also sparked a keener interest in polymer physics, and I will be considering continuing this project for my final year.
Diblock copolymers are polymers that consists of two types of monomer, A and B. The properties of systems of these polymers can depend on many factors; one of them being the degree of ordering. Investigations have already been done into the mechanisms behind the ordering of such systems under external fields. This project was to examine the mechanisms of ordering under a shear-flow field.
2D simulations were used to investigate the effect of shear flow on the ordering of a diblock copolymer melt. The parameters for the simulation were set at: = 0.5, = 0.5, = 0.02. The simulations were run systematically, varying three values: thickness, temperature and shear.
Before shear could be applied, an equilibrium had to be reached for each simulation. Therefore, four thicknesses were used, Ny = 6, 8, 10, 12, and for each thickness, the temperature, τ, was varied between 0.25, 0.30 and 0.35. This produced a total of 12 systems.
From this point, it could be assumed that any further changes to the system were the result of the shear flow, and not a different factor. 5 different shear-flow rates were applied; 0.0001, 0.0005, 0.001, 0.003, 0.005. For each simulation, a series of images were taken to show the time-evolution of the system.
Once a simulation was complete, it was put through a Fourier-transform to show the time-evolution of the degree of ordering.
The simulations were run using Linux. Each simulation took about a day to complete, and analysis took a few hours longer. However, there were some complications with the code. These complications slowed the rate of research down significantly. There were some issues that were also not completely resolved in time; particularly regarding the Fourier-transform.
All in all, enough data was collected to make significant headway into this research and will continue to develop further.
*To view Aaron’s project poster, please click on the thumbnail below: