Nanotech 2004 Vol. 3
Nanotech 2004 Vol. 3
Technical Proceedings of the 2004 NSTI Nanotechnology Conference and Trade Show, Volume 3

Atomic and Mesoscale Modelling of Nanoscale Phenomena Chapter 3

Modeling of PDMS - Silica Nanocomposites

Authors: J.S. Smith, G.D. Smith and O. Borodin

Affilation: University of Utah, United States

Pages: 115 - 118

Keywords: nanocomposite, molecular dynamics, polymer simulation, quantum chemistry, polymers, modeling

Abstract:
A hydrogen bonding pathway between polydimethylsiloxane (PDMS) and hydroxyl groups on a silica surface was studied using quantum chemistry calculations of disiloxane and hexamethyldisiloxane molecules with small silica clusters. A newly developed classical force field for PDMS was used in atomistic molecular dynamics simulation studies of PDMS/silica nanocomposites to determine the effect of these interactions on the dynamics and structure of PDMS. A three nanometer silica particle (b-crystobalite) with (111) surface hydroxyl group density of 4.8 OH groups/nm2 was simulated in a PDMS melt in the temperature range of 300 to 500K. The density and structure of PDMS chains near the silica surface were strongly influenced by the hydrogen bonding interaction which is not properly represented in other current force fields. Residence time correlation analysis confirmed that PDMS oxygen silica surface hydrogen atom dynamics were consistent with polymer hydrogen bonding. The dynamics of backbone atoms in the PDMS chains are an order of magnitude slower than bulk polymer at the same temperature consistent with experimental findings. Results of this study are compared with simulation and experimental results on nanocomposite systems.

Modeling of PDMS - Silica Nanocomposites

ISBN: 0-9728422-9-2
Pages: 561
Hardcopy: $79.95