(13j) Hierarchical Multiscale Simulations of Polymeric Nanostructured Materials

The theoretical study of hybrid polymeric materials at the molecular level is an emerging research area, due to basic scientific questions, as well as the broad spectrum of technological applications in which they are involved. Here we a hierarchical simulation approach in order to study quantitatively multi-phase polymeric nanostructured systems, over a broad range of length and time scales. Our approach combines quantum calculations as well as atomistic and coarse-grained (CG) dynamic simulations [1-4], and allows quantitative modeling of specific complex hybrid systems over a very broad range of lengths and times. In addition, through a systematic approach that involves dynamic information from the atomistic MD simulations, dynamic properties can be quantitatively predicted through the CG simulations without any adjustable parameter and directly compared to experimental data.

The proposed scheme consists of: (a) Ab-initio (density functional theory, DFT) calculations of small molecules adsorbed on solid surfaces. These calculations allow us to accurately describe the interaction energy between a small fragment of the polymer (e.g. a monomer) and the solid layer. Furthermore, they can be used in order to construct an accurate classical all-atom force field. (b) Atomistic molecular dynamics (MD) simulations of short polymer chains/solid interfacial systems and polymer nanocomposites. Various properties related to density, structure and dynamics of the hybrid materials are predicted. We also develop a methodology to obtain systematically CG models from the atomistic description, for specific polymer/solid systems. (c) Mesoscopic coarse-grained (CG) simulations of specific polymer/solid (e.g. PS/Au) surfaces. The CG model is first validated by studying small PS/Au systems, using all-atom and coarse-grained MD simulations. Then, the CG model is used to study the structural, conformational and dynamical properties of various films and longer polymer chains.

As examples we consider the following cases:

(a) Polymer/Metal (Polystyrene/gold) interfaces) [3],

(b) Graphene based polar (polyethylene oxide) and non-polar (polyethylene, polystyrene) polymer nanocomposites [1,2], and

(c) Self-assembled miktoarm star copolymers [4]

In all above cases, results are compared against theoretical predictions and experimental data.

References

[1] A. Rissanou et al. Macromolecules, 50, 6273 (2017); A. Rissanou and V. Harmandaris, Macromolecules, 48, 2761 (2015); Soft Matter, 10, 2876 (2014); C. Baig and V. Harmandaris, Macromolecules, 43, 3156 (2010).

[2] P. Bacova, A.N. Rissanou, and V. Harmandaris, Macromolecules, 48, 9024–9038 (2015).

[3] K. Johnston and V. Harmandaris, Soft Matter, 2013, 9, 6696 (Review); Macromolecules, 2013, 46, 5741; Soft Matter, 2012, 8, 6320; J. Phys. Chem. C., 2011, 115, 14707.

[4] P. Bačová, E. Glynos, V. Harmandaris, to be submitted.