Confined Nanoparticle Composite (nanoPtclWall.pre)

Keywords:

nanocomposites, phase transition

Problem description

This simulation can be performed with a PSimPlus license.

This example demonstrates the hybrid-SCFT algorithm for incorporating nanoparticles into a copolymer melt. This example also includes confinement for copolymers and nanoparticles in the form of parallel, flat surfaces. These surfaces have neutral specific interactions with each of the copolymer species and hard-contact interactions with the spherical nanoparticles. The nanoparticle surfaces are preferentially wet by the minority “B” monomers on the copolymer chains. This example’s default is set to insert nanoparticles as the simulation proceeds to illustrate the effect of increased nanoparticle loading. As the number of nanoparticles increases you will be able to see the separate interior domains become connected.

Input File Features

Files: nanoPtclWall.pre.

The variables in the Setup tab are

  • NX (Number of cells in the x-dir)
  • NY (Number of cells in the y-dir)
  • NZ (Number of cells in the z-dir)
  • pRadius (Radius of nanoparticles) in units of Rg
  • fA (Length fraction of ‘A’ block)
  • fB (Length fraction of ‘B’ block)
  • chiNAB Flory chi*N parameter between the two chemically distinct block monomers
  • chiN_AP Flory chi*N parameter between the A monomers and nanoparticle surfaces
  • chiN_BP Flory chi*N parameter between the B monomers and nanoparticle surfaces
  • maxParticles (Maximum number of spherical particles)

Creating the run space

The Confined Nanoparticle Composite example is accessed from within PSimComposer by the following actions:

  • Select the New from Template menu item in the File menu.
  • In the resulting New from Template window, select PSimPlus and then press the arrow button to the left.
  • Select “Confined Nanoparticle Composite” and press the Choose button.
  • In the resulting dialog, press the Save button to create a copy of this example in your run area.

The basic variables of this problem should now be settable in text boxes in the right pane of the “Setup” window, as shown in Fig. 84.

../../../_images/nanoPtclWallSetupWin.png

Figure 84: Setup window for the Confined Nanoparticle Composite example.

Running the simulation

After performing the above actions, continue as follows:

  • Press the Save And Setup button in the upper right corner.
  • Proceed to the run window as instructed by pressing the Run button in the left column of buttons.
  • Note: because the initial random state depends on the number of processors, the final simulation state can depend on the number of processors chosen if running in parallel. The results in this example are produced by running on two processors. The parallel run options can be accessed by going to the ‘MPI’ tab on the left side of the Run button window.
  • To run the file, click on the Run button in the upper right corner. of the window. You will see the output of the run in the right pane. The run has completed when you see the output, “Engine completed successfully.” This is shown in Fig. 85.
../../../_images/nanoPtclWallRunWin.png

Figure 85: The Run window at the end of execution.

Visualizing the results

After performing the above actions, continue as follows:

  • Proceed to the Visualize window as instructed by pressing the Visualize button in the left column of buttons.
  • Press the “Open” button to begin visualizing.
  • Go to the Scalar Data Variable in the CONTROLS panel on the left and press the arrow to the left
  • Check one of the MonomerDensity boxes (try the totEthyDens database) This selects all of the datafiles for this physical field ‘totEthyDens’. This first *h5 file will be shown first. NOTE: do not select the particle data before selecting the monomer field data, as the field grid needs to be loaded first
  • Go to the Particle Data in the *CONTROLS panel and select ‘Particle Centers’ tab and check the red highlighted ‘Particle Centers’ box.
  • Move the Dump slider at the bottom of the window to the last position to see the final simulation state.
  • Choose the Colors button at the top of the Visualization pane and select ‘orangehot’ palette to match the Fig. 86.
../../../_images/nanoPtclWallVizWin-4.png

Figure 86: Visualization of Confined Nanoparticle Composite as a color contour plot. Note, visualization details such as the color of the nanoparticles can be fully accessed through the VisIt GUI (right click on the visualization window).

Further Experiments

Change the relative sizes of the nanoparticle/monomer chi interaction parameters to see the particles segregate to the majority phase of the copolymer.

Change the sizes of the copolymer blocks to see how different phases are affected by the presence of nanoparticles.

Change the size of the nanoparticles. NOTE, if you want to simulate nanoparticles that are smaller then the overall resolution of the simulation will have to be increased.