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Failure and Mechanical Properties of Glassy Diblock Copolymer Thin Films

https://doi.org/10.1021/acs.macromol.2c01031

Zhang, Tianren; Wang, Ning; Riggleman, Robert A. (December 2022, Macromolecules)

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Decoupling the Impact of Entanglements and Mobility on the Failure Properties of Ultrathin Polymer Films

https://doi.org/10.1021/acs.macromol.2c01435

Bay, R. Ko̅nane; Zhang, Tianren; Shimomura, Shinichiro; Ilton, Mark; Tanaka, Keiji; Riggleman, Robert A.; Crosby, Alfred J. (October 2022, Macromolecules)

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Thickness-Dependent Mechanical Failure in Thin Films of Glassy Polymer Bidisperse Blends

https://doi.org/10.1021/acs.macromol.1c01630

Zhang, Tianren; Riggleman, Robert A. (January 2022, Macromolecules)

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Load-bearing entanglements in polymer glasses

https://doi.org/10.1126/sciadv.abg9763

Bukowski, Cynthia; Zhang, Tianren; Riggleman, Robert A.; Crosby, Alfred J. (September 2021, Science Advances)

Through a combined approach of experiment and simulation, this study quantifies the role of entanglements in determining the mechanical properties of glassy polymer blends. Uniaxial extension experiments on 100-nm films containing a bidisperse mixture of polystyrene enable quantitative comparison with molecular dynamics (MD) simulations of a coarse-grained model for polymer glasses, where the bidisperse blends allow us to systematically tune the entanglement density of both systems. In the MD simulations, we demonstrate that not all entanglements carry substantial load at large deformation, and our analysis allows the development of a model to describe the number of effective, load-bearing entanglements per chain as a function of blend ratio. The film strength measured experimentally and the simulated film toughness are quantitatively described by a model that only accounts for load-bearing entanglements.
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