Reactivity-Guided Depercolation Processes Determine Fracture Behavior in End-Linked Polymer Networks.

Autor:	Beech HK; NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, North Carolina 27708, United States.; Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States., Wang S; NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, North Carolina 27708, United States.; Department of Chemistry, Duke University, Durham, North Carolina 27708, United States., Sen D; NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, North Carolina 27708, United States.; Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States., Rota D; NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, North Carolina 27708, United States.; Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States., Kouznetsova TB; NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, North Carolina 27708, United States.; Department of Chemistry, Duke University, Durham, North Carolina 27708, United States., Arora A; Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States., Rubinstein M; NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, North Carolina 27708, United States.; Department of Chemistry, Duke University, Durham, North Carolina 27708, United States.; Departments of Mechanical Engineering and Materials Sciences, Biomedical Engineering, and Physics, Duke University, Durham, North Carolina 27708, United States., Craig SL; NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, North Carolina 27708, United States.; Department of Chemistry, Duke University, Durham, North Carolina 27708, United States., Olsen BD; NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, North Carolina 27708, United States.; Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
Jazyk:	angličtina
Zdroj:	ACS macro letters [ACS Macro Lett] 2023 Dec 19; Vol. 12 (12), pp. 1685-1691. Date of Electronic Publication: 2023 Dec 01.
DOI:	10.1021/acsmacrolett.3c00559
Abstrakt:	The fracture of polymer networks is tied to the molecular behavior of strands within the network, yet the specific molecular-level processes that determine the mechanical limits of a network remain elusive. Here, the question of reactivity-guided fracture is explored in otherwise indistinguishable end-linked networks by tuning the relative composition of strands with two different mechanochemical reactivities. Increasing the substitution of less mechanochemically reactive ("strong") strands into a network comprising more reactive ("weak") strands has a negligible impact on the fracture energy until the strong strand content reaches approximately 45%, at which point the fracture energy sharply increases with strong strand content. This aligns with the measured strong strand percolation threshold of 48 ± 3%, revealing that depercolation, or the loss of a percolated network structure, is a necessary criterion for crack propagation in a polymer network. Coarse-grained fracture simulations agree closely with the tearing energy trend observed experimentally, confirming that weak strand scissions dominate the failure until the strong strands approach percolation. The simulations further show that twice as many strands break in a mixture than in a pure network.
Databáze:	MEDLINE
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