Siloxane Molecules: Nonlinear Elastic Behavior and Fracture Characteristics


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Date

2023-02-28

Publication Type

Journal Article

ETH Bibliography

yes

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Abstract

Fracture phenomena in soft materials span multiple length and time scales. This poses a major challenge in computational modeling and predictive materials design. To pass quantitatively from molecular to continuum scales, a precise representation of the material response at the molecular level is vital. Here, we derive the nonlinear elastic response and fracture characteristics of individual siloxane molecules using molecular dynamics (MD) studies. For short chains, we find deviations from classical scalings for both the effective stiffness and mean chain rupture times. A simple model of a nonuniform chain of Kuhn segments captures the observed effect and agrees well with MD data. We find that the dominating fracture mechanism depends on the applied force scale in a nonmonotonic fashion. This analysis suggests that common polydimethylsiloxane (PDMS) networks fail at cross-linking points. Our results can be readily lumped into coarse-grained models. Although focusing on PDMS as a model system, our study presents a general procedure to pass beyond the window of accessible rupture times in MD studies employing mean first passage time theory, which can be exploited for arbitrary molecular systems.

Publication status

published

Editor

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Volume

56 (4)

Pages / Article No.

1303 - 1310

Publisher

American Chemical Society

Event

Edition / version

Methods

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Subject

Deformation; Molecules; Nucleic acid structure; Polymerization; Solvents

Organisational unit

09573 - Dufresne, Eric (ehemalig) / Dufresne, Eric (former) check_circle
03986 - Gambardella, Pietro / Gambardella, Pietro check_circle
02646 - Institut für Polymere / Institute of Polymers

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