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Freudenberg, Jan
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Publications (4/4 displayed)
- 2024Breaking Strong Alkynyl-Phenyl Bonds: Poly(para-phenylene ethynylene)s under Mechanical Stress [data]
- 2022Crosslinking Super Yellow to produce super OLEDs: Crosslinking with azides enables improved performance
- 20195,7,12,14‐Tetrafunctionalized 6,13‐Diazapentacenescitations
- 2015Reverse Engineering of Conjugated Microporous Polymers: Defect Structures of Tetrakis(4‐ethynylphenyl)stannane Networkscitations
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document
Breaking Strong Alkynyl-Phenyl Bonds: Poly(para-phenylene ethynylene)s under Mechanical Stress [data]
Abstract
Stronger chemical bonds withstand higher mechanical forces, and thus, rupture of single bonds is preferred over the rupture of double or triple bonds or aromatic rings. We investigated bond scission in poly(dialkyl-p-phenyleneethynylene)s (PPEs), a fully conjugated polymer. In a scale-bridging approach using electron-paramagnetic resonance spectroscopy and gel permeation chromatography of cryo-milled samples, in combination with density-functional theory calculations and coarse-grained simulations, we conclude that mechanical force cleaves the sp-sp2 bond of PPEs (bond dissociation energy as high as 600 kJ mol-1). Bond scission primarily occurs in shear bands with locally increased shear stresses. The scission occurs in the middle of the PPE chains. Breaking sp-sp2 bonds into free radicals thus is feasible but requires significant mechanical force and efficient stress concentration.