1. MD Simulations of PEO/PMMA blends May 6 th 2008 F. Alvarez, A. Arbe, Prof. J. Colmenero M. Brodeck, Prof. D. Richter Universidad del Pais Vasco Forschungszentrum Jülich Eurothesis

2. Eurothesis, sponsored by SoftComp, spending time at different SoftComp labs during the PhD  San Sebastian and Jülich MD-simulations of PEO and polymer blends (PEO/PMMA) with very different T g Validation of simulations by experiments (PEO) Analysis of fully atomistic simulations Rouse mode analysis Coarse grain simulations? Motivation What is this all about?

3. Overview Introduction –Validation PEO/PMMA in blend –Structural properties –Self-correlation functions and non-Gaussianity –Mean Square Displacements –Rouse Modes

4. Introduction to the Simulation Setup and Software Software by Simulation engine: Discover –Periodic boundary conditions Densities determined by NPT-simulations Forcefield: COMPASS –condensed-phase optimized molecular potentials for atomistic simulation studies Simulation time: 100 ns Δt = 1 fs 100,000,000 steps

5. PEO as Homopolymer Confirmed results Dynamics of individual hydrogen atoms protonated sample* Collective dynamics deuterated sample TOFTOF *A.-C.Genix, A.Arbe, F.Alvarez, J.Colmenero, L.Willner and D.Richter, Phys.Rev.E, 2005, 72, 031808. *M.Tyagi, A.Arbe, J.Colmenero, B.Frick and J.R.Stewart, Macromolecules, 2006, 39, 3007.

6. PEO as Homopolymer Confirmed results Dynamics of individual hydrogen atoms protonated sample* Collective dynamics deuterated sample NSE temperature corrected

7. PEO/PMMA in blend Introduction Simulating the blend –5 PEO chains 43 monomers 15 PMMA chains 25 monomers  7170 atoms cell size ~41.5 Å –Density determined by NPT T: 300 (running), 350 and 400 K 100 ns for each temperature Huge data files, ~90Gb for 100ns * * Povray

8. PEO/PMMA in blend Structure

10. Composition of the blend (weight): 20% PEO, 80% PMMA

11. PEO/PMMA in blend Comparing the Blend with the Homopolymer

18. PEO/PMMA in blend MSD of PEO-hydrogens Movement of PEO atoms restricted by the rather stiff PMMA-matrix

19. PEO/PMMA in blend MSD of hydrogen-atoms Methyl-group Ester-group Main-chain Complex, stiff structure

20. PEO/PMMA in blend Comparing the MSD for two temperatures

21. PEO/PMMA in blend Forming Blobs

22. PEO/PMMA in blend Results – Rouse Modes We investigate the behavior of PEO in the blend! Fourier transformation of blob-coordinates

23. PEO/PMMA in blend Results – Rouse Modes

24. PEO/PMMA in blend MSD of hydrogen-atoms Methyl-group Ester-group Main-chain Complex, stiff structure Rouse regime

25. PEO/PMMA in blend MSD of hydrogen-atoms Methyl-group Ester-group Main-chain Complex, stiff structure Rouse regime

26. PEO/PMMA in blend Results – Rouse Modes

29. Conclusion Simulation of homopolymer validated by various experimental techniques Simulation of the blend: extraction of valuable information from full trajectories Development of a second peak for high Δt Caging-effect or simulation artifact? Formation of blobs  Rouse mode analysis

30. Thank you… Softcomp Eurothesis Project DIPC, University of the Basque Country San Sebastian –J. Colmenero –F. Alvarez –A. Arbe Forschungszentrum Jülich –D. Richter

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34. PEO as Homopolymer Coarse Graining PEO Micro – Meso mapping –Simplest idea: 1 monomer = 1 blob –Obtain probabilities from MD simulations Bond distance Bond angle … –Assume that the probability distributions factorize –Boltzmann factors of interaction potentials

35. PEO as Homopolymer Coarse Graining PEO Micro – Meso mapping –Determine potentials and forces –Repeat for different temperatures –Compile into tables (no analytical form necessary) –Write software (or use free open source alternative) –LAMMPS – Large-scale Atomic/Molecular Massively Parallel Simulator, lammps.sandia.gov

36. PEO as Homopolymer Results – Coarse Graining From these probabilities we can calculate an effective potential

37. PEO as Homopolymer Coarse Graining – Effective Potentials

38. PEO as Homopolymer Coarse Graining – Non-bond interactions