FisMat2017 - Submission - View

Abstract's title: Hybrid particle-field molecular dynamics study of Silica-Polystyrene nanocomposites
Submitting author: Gianmarco Munaò
Affiliation: University of Salerno
Affiliation Address: Department of Chemistry and Biology “Adolfo Zambelli”, University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano (SA), Italy .
Country: Italy
Oral presentation/Poster (Author's request): Oral presentation
Other authors and affiliations: Antonio De Nicola (University of Salerno), Antonio Pizzirusso (University of Salerno) and Giuseppe Milano (University of Salerno)

Polymer composites based on nanosized particles are experiencing a very fast growth during the last years due to their industrial applications and improved physical properties [1]. The so-called nanocomposite materials are formed by filling a polymer matrix with inorganic particles whose typical dimensions are of the order of a few nanometers. Interest in such materials comes from the possiblity to control the effects that polymer/filler interactions have on the polymer chains, in terms of free volume, crystallinity, mobility, and conformation with the aim to improve the material properties [2]. However, a well-defined control of the underlying interactions in nanocomposites is not a simple task, nor experimentally neither theoretically. In computer simulations, the main problem concerns the very long times usually required to get a proper relaxation of the system.

Here we present a coarse-grained model suitable for polymer nanocomposites which combines the Iterative-Boltzmann-Inversion method [3], the hybrid particle-field representation of non-bonded interactions [4], and a convenient description of a solid nanoparticle suitable for hybrid particle-field models [5]. By means of the proposed approach we show that molecular simulations of polystyrene-silica nanocomposites can be succesfully performed. In particular, we document how the presence of a single silica nanoparticle significantly influences the structure of the polymer chains in terms of gyration radius and autocorrelation functions of the end-to-end distances. Furthemore, by grafting the nanoparticle with polystyrene chains we document a change in the swelling state of the grafted corona, such a change depending on the chain length and on the grafting density. This phenomenon, known as “wet brush to dry brush transition” has been observed also experimentally and plays a key role in determining the behavior of the nanocomposite.

[1] J. H. Koo, Polymer Nanocomposites: Processing, Characterization, and Application (New York: McGraw-Hill, 2006).

[2] V. Ganesan and A. Jayaraman, Soft Matter 10, 13 (2014).

[3] A. Ghanbari, T. V. M. Ndoro, F. Leroy, M. Rahimi, M. C. Böhm and F. Müller-Plathe, Macromolecules 45, 572 (2012).

[4] G. Milano and T. Kawakatsu, J. Chem. Phys. 130, 214106 (2009).

[5] A. De Nicola, T. Kawakatsu, F. Müller-Plathe and G. Milano, Eur. Phys. J. Special Topics 225, 1817 (2016).