Speaker
Description
State-of-the-art experimental techniques such as small-angle neutron scattering (SANS) and neutron spin echo (NSE) spectroscopy provide valuable insights into the unique structural characteristics and segmental and diffusion dynamics of polymers in their molten state. However, there are often cases where analysing experimental findings with such methods is challenging. We mention for example the case of minor contamination of ring polymer melts by linear analogues which can significantly affect polymer relaxation but also the case of subtle structural differences along the polymer chain which can lead to different spectra.
Molecular dynamics (MD) simulations can effectively address these issues by allowing precise control over the sample's composition. Recent theoretical advancements and the availability of atomistic force fields enable the predictions of neutron scattering spectra from MD simulations with remarkable accuracy.
In this presentation, we will outline the theoretical framework for predicting SANS and NSE spectra based on the analysis of microsecond-long atomistic MD trajectories and we will illustrate the application of such a methodology with specific examples, including ring polyethylene oxide (PEO) melts [1], mixtures of PEO rings with linear counterparts [2,3], and polyethylene glycol/silica nanocomposites [4].
Direct comparison of the MD-extracted neutron scattering spectra against available experimental measurements conducted under identical conditions and system compositions will also be presented, revealing remarkable agreement between the two approaches.
References
[1] D.G. Tsalikis, et al., Macromolecules 50, 2565-2584, (2017).
[2] G.D. Papadopoulos, D.G. Tsalikis, and V.G. Mavrantzas, Polymers 8, 21, (2016).
[3] D.G. Tsalikis, and V.G. Mavrantzas, Macromolecules 53, 803-820, (2020).
[4] E.N. Skountzos, D.G. Tsalikis, P.S. Stephanou, and V.G. Mavrantzas, Macromolecules 54, 4470-4487, (2021).
